Provided by: valgrind_3.7.0-0ubuntu3_amd64 bug


       valgrind - a suite of tools for debugging and profiling programs


       valgrind [valgrind-options] [your-program] [your-program-options]


       Valgrind is a flexible program for debugging and profiling Linux executables. It consists
       of a core, which provides a synthetic CPU in software, and a series of debugging and
       profiling tools. The architecture is modular, so that new tools can be created easily and
       without disturbing the existing structure.

       Some of the options described below work with all Valgrind tools, and some only work with
       a few or one. The section MEMCHECK OPTIONS and those below it describe tool-specific

       This manual page covers only basic usage and options. For more comprehensive information,
       please see the HTML documentation on your system:
       $INSTALL/share/doc/valgrind/html/index.html, or online:


       The single most important option.

       --tool=<toolname> [default: memcheck]
           Run the Valgrind tool called toolname, e.g. Memcheck, Cachegrind, etc.


       These options work with all tools.

       -h --help
           Show help for all options, both for the core and for the selected tool. If the option
           is repeated it is equivalent to giving --help-debug.

           Same as --help, but also lists debugging options which usually are only of use to
           Valgrind's developers.

           Show the version number of the Valgrind core. Tools can have their own version
           numbers. There is a scheme in place to ensure that tools only execute when the core
           version is one they are known to work with. This was done to minimise the chances of
           strange problems arising from tool-vs-core version incompatibilities.

       -q, --quiet
           Run silently, and only print error messages. Useful if you are running regression
           tests or have some other automated test machinery.

       -v, --verbose
           Be more verbose. Gives extra information on various aspects of your program, such as:
           the shared objects loaded, the suppressions used, the progress of the instrumentation
           and execution engines, and warnings about unusual behaviour. Repeating the option
           increases the verbosity level.

       --trace-children=<yes|no> [default: no]
           When enabled, Valgrind will trace into sub-processes initiated via the exec system
           call. This is necessary for multi-process programs.

           Note that Valgrind does trace into the child of a fork (it would be difficult not to,
           since fork makes an identical copy of a process), so this option is arguably badly
           named. However, most children of fork calls immediately call exec anyway.

           This option only has an effect when --trace-children=yes is specified. It allows for
           some children to be skipped. The option takes a comma separated list of patterns for
           the names of child executables that Valgrind should not trace into. Patterns may
           include the metacharacters ?  and *, which have the usual meaning.

           This can be useful for pruning uninteresting branches from a tree of processes being
           run on Valgrind. But you should be careful when using it. When Valgrind skips tracing
           into an executable, it doesn't just skip tracing that executable, it also skips
           tracing any of that executable's child processes. In other words, the flag doesn't
           merely cause tracing to stop at the specified executables -- it skips tracing of
           entire process subtrees rooted at any of the specified executables.

           This is the same as --trace-children-skip, with one difference: the decision as to
           whether to trace into a child process is made by examining the arguments to the child
           process, rather than the name of its executable.

       --child-silent-after-fork=<yes|no> [default: no]
           When enabled, Valgrind will not show any debugging or logging output for the child
           process resulting from a fork call. This can make the output less confusing (although
           more misleading) when dealing with processes that create children. It is particularly
           useful in conjunction with --trace-children=. Use of this option is also strongly
           recommended if you are requesting XML output (--xml=yes), since otherwise the XML from
           child and parent may become mixed up, which usually makes it useless.

       --vgdb=<no|yes|full> [default: yes]
           Valgrind will provide "gdbserver" functionality when --vgdb=yes or --vgdb=full is
           specified. This allows an external GNU GDB debugger to control and debug your program
           when it runs on Valgrind. See ???  for a detailed description.

           If the embedded gdbserver is enabled but no gdb is currently being used, the ???
           command line utility can send "monitor commands" to Valgrind from a shell. The
           Valgrind core provides a set of ???. A tool can optionally provide tool specific
           monitor commands, which are documented in the tool specific chapter.

           --vgdb=full incurs significant performance overheads.

       --vgdb-error=<number> [default: 999999999]
           Use this option when the Valgrind gdbserver is enabled with --vgdb=yes or --vgdb=full.
           Tools that report errors will wait for "number" errors to be reported before freezing
           the program and waiting for you to connect with GDB. It follows that a value of zero
           will cause the gdbserver to be started before your program is executed. This is
           typically used to insert GDB breakpoints before execution, and also works with tools
           that do not report errors, such as Massif.

       --track-fds=<yes|no> [default: no]
           When enabled, Valgrind will print out a list of open file descriptors on exit. Along
           with each file descriptor is printed a stack backtrace of where the file was opened
           and any details relating to the file descriptor such as the file name or socket

       --time-stamp=<yes|no> [default: no]
           When enabled, each message is preceded with an indication of the elapsed wallclock
           time since startup, expressed as days, hours, minutes, seconds and milliseconds.

       --log-fd=<number> [default: 2, stderr]
           Specifies that Valgrind should send all of its messages to the specified file
           descriptor. The default, 2, is the standard error channel (stderr). Note that this may
           interfere with the client's own use of stderr, as Valgrind's output will be
           interleaved with any output that the client sends to stderr.

           Specifies that Valgrind should send all of its messages to the specified file. If the
           file name is empty, it causes an abort. There are three special format specifiers that
           can be used in the file name.

           %p is replaced with the current process ID. This is very useful for program that
           invoke multiple processes. WARNING: If you use --trace-children=yes and your program
           invokes multiple processes OR your program forks without calling exec afterwards, and
           you don't use this specifier (or the %q specifier below), the Valgrind output from all
           those processes will go into one file, possibly jumbled up, and possibly incomplete.

           %q{FOO} is replaced with the contents of the environment variable FOO. If the {FOO}
           part is malformed, it causes an abort. This specifier is rarely needed, but very
           useful in certain circumstances (eg. when running MPI programs). The idea is that you
           specify a variable which will be set differently for each process in the job, for
           example BPROC_RANK or whatever is applicable in your MPI setup. If the named
           environment variable is not set, it causes an abort. Note that in some shells, the {
           and } characters may need to be escaped with a backslash.

           %% is replaced with %.

           If an % is followed by any other character, it causes an abort.

           Specifies that Valgrind should send all of its messages to the specified port at the
           specified IP address. The port may be omitted, in which case port 1500 is used. If a
           connection cannot be made to the specified socket, Valgrind falls back to writing
           output to the standard error (stderr). This option is intended to be used in
           conjunction with the valgrind-listener program. For further details, see the
           commentary in the manual.


       These options are used by all tools that can report errors, e.g. Memcheck, but not

       --xml=<yes|no> [default: no]
           When enabled, the important parts of the output (e.g. tool error messages) will be in
           XML format rather than plain text. Furthermore, the XML output will be sent to a
           different output channel than the plain text output. Therefore, you also must use one
           of --xml-fd, --xml-file or --xml-socket to specify where the XML is to be sent.

           Less important messages will still be printed in plain text, but because the XML
           output and plain text output are sent to different output channels (the destination of
           the plain text output is still controlled by --log-fd, --log-file and --log-socket)
           this should not cause problems.

           This option is aimed at making life easier for tools that consume Valgrind's output as
           input, such as GUI front ends. Currently this option works with Memcheck, Helgrind,
           DRD and SGcheck. The output format is specified in the file
           docs/internals/xml-output-protocol4.txt in the source tree for Valgrind 3.5.0 or

           The recommended options for a GUI to pass, when requesting XML output, are: --xml=yes
           to enable XML output, --xml-file to send the XML output to a (presumably GUI-selected)
           file, --log-file to send the plain text output to a second GUI-selected file,
           --child-silent-after-fork=yes, and -q to restrict the plain text output to critical
           error messages created by Valgrind itself. For example, failure to read a specified
           suppressions file counts as a critical error message. In this way, for a successful
           run the text output file will be empty. But if it isn't empty, then it will contain
           important information which the GUI user should be made aware of.

       --xml-fd=<number> [default: -1, disabled]
           Specifies that Valgrind should send its XML output to the specified file descriptor.
           It must be used in conjunction with --xml=yes.

           Specifies that Valgrind should send its XML output to the specified file. It must be
           used in conjunction with --xml=yes. Any %p or %q sequences appearing in the filename
           are expanded in exactly the same way as they are for --log-file. See the description
           of --log-file for details.

           Specifies that Valgrind should send its XML output the specified port at the specified
           IP address. It must be used in conjunction with --xml=yes. The form of the argument is
           the same as that used by --log-socket. See the description of --log-socket for further

           Embeds an extra user comment string at the start of the XML output. Only works when
           --xml=yes is specified; ignored otherwise.

       --demangle=<yes|no> [default: yes]
           Enable/disable automatic demangling (decoding) of C++ names. Enabled by default. When
           enabled, Valgrind will attempt to translate encoded C++ names back to something
           approaching the original. The demangler handles symbols mangled by g++ versions 2.X,
           3.X and 4.X.

           An important fact about demangling is that function names mentioned in suppressions
           files should be in their mangled form. Valgrind does not demangle function names when
           searching for applicable suppressions, because to do otherwise would make suppression
           file contents dependent on the state of Valgrind's demangling machinery, and also slow
           down suppression matching.

       --num-callers=<number> [default: 12]
           Specifies the maximum number of entries shown in stack traces that identify program
           locations. Note that errors are commoned up using only the top four function locations
           (the place in the current function, and that of its three immediate callers). So this
           doesn't affect the total number of errors reported.

           The maximum value for this is 50. Note that higher settings will make Valgrind run a
           bit more slowly and take a bit more memory, but can be useful when working with
           programs with deeply-nested call chains.

       --error-limit=<yes|no> [default: yes]
           When enabled, Valgrind stops reporting errors after 10,000,000 in total, or 1,000
           different ones, have been seen. This is to stop the error tracking machinery from
           becoming a huge performance overhead in programs with many errors.

       --error-exitcode=<number> [default: 0]
           Specifies an alternative exit code to return if Valgrind reported any errors in the
           run. When set to the default value (zero), the return value from Valgrind will always
           be the return value of the process being simulated. When set to a nonzero value, that
           value is returned instead, if Valgrind detects any errors. This is useful for using
           Valgrind as part of an automated test suite, since it makes it easy to detect test
           cases for which Valgrind has reported errors, just by inspecting return codes.

       --show-below-main=<yes|no> [default: no]
           By default, stack traces for errors do not show any functions that appear beneath main
           because most of the time it's uninteresting C library stuff and/or gobbledygook.
           Alternatively, if main is not present in the stack trace, stack traces will not show
           any functions below main-like functions such as glibc's __libc_start_main.
           Furthermore, if main-like functions are present in the trace, they are normalised as
           (below main), in order to make the output more deterministic.

           If this option is enabled, all stack trace entries will be shown and main-like
           functions will not be normalised.

       --fullpath-after=<string> [default: don't show source paths]
           By default Valgrind only shows the filenames in stack traces, but not full paths to
           source files. When using Valgrind in large projects where the sources reside in
           multiple different directories, this can be inconvenient.  --fullpath-after provides a
           flexible solution to this problem. When this option is present, the path to each
           source file is shown, with the following all-important caveat: if string is found in
           the path, then the path up to and including string is omitted, else the path is shown
           unmodified. Note that string is not required to be a prefix of the path.

           For example, consider a file named /home/janedoe/blah/src/foo/bar/xyzzy.c. Specifying
           --fullpath-after=/home/janedoe/blah/src/ will cause Valgrind to show the name as

           Because the string is not required to be a prefix, --fullpath-after=src/ will produce
           the same output. This is useful when the path contains arbitrary machine-generated
           characters. For example, the path /my/build/dir/C32A1B47/blah/src/foo/xyzzy can be
           pruned to foo/xyzzy using --fullpath-after=/blah/src/.

           If you simply want to see the full path, just specify an empty string:
           --fullpath-after=. This isn't a special case, merely a logical consequence of the
           above rules.

           Finally, you can use --fullpath-after multiple times. Any appearance of it causes
           Valgrind to switch to producing full paths and applying the above filtering rule. Each
           produced path is compared against all the --fullpath-after-specified strings, in the
           order specified. The first string to match causes the path to be truncated as
           described above. If none match, the full path is shown. This facilitates chopping off
           prefixes when the sources are drawn from a number of unrelated directories.

       --suppressions=<filename> [default: $PREFIX/lib/valgrind/default.supp]
           Specifies an extra file from which to read descriptions of errors to suppress. You may
           use up to 100 extra suppression files.

       --gen-suppressions=<yes|no|all> [default: no]
           When set to yes, Valgrind will pause after every error shown and print the line:

                   ---- Print suppression ? --- [Return/N/n/Y/y/C/c] ----

           The prompt's behaviour is the same as for the --db-attach option (see below).

           If you choose to, Valgrind will print out a suppression for this error. You can then
           cut and paste it into a suppression file if you don't want to hear about the error in
           the future.

           When set to all, Valgrind will print a suppression for every reported error, without
           querying the user.

           This option is particularly useful with C++ programs, as it prints out the
           suppressions with mangled names, as required.

           Note that the suppressions printed are as specific as possible. You may want to common
           up similar ones, by adding wildcards to function names, and by using frame-level
           wildcards. The wildcarding facilities are powerful yet flexible, and with a bit of
           careful editing, you may be able to suppress a whole family of related errors with
           only a few suppressions.

           Sometimes two different errors are suppressed by the same suppression, in which case
           Valgrind will output the suppression more than once, but you only need to have one
           copy in your suppression file (but having more than one won't cause problems). Also,
           the suppression name is given as <insert a suppression name here>; the name doesn't
           really matter, it's only used with the -v option which prints out all used suppression

       --db-attach=<yes|no> [default: no]
           When enabled, Valgrind will pause after every error shown and print the line:

                   ---- Attach to debugger ? --- [Return/N/n/Y/y/C/c] ----

           Pressing Ret, or N Ret or n Ret, causes Valgrind not to start a debugger for this

           Pressing Y Ret or y Ret causes Valgrind to start a debugger for the program at this
           point. When you have finished with the debugger, quit from it, and the program will
           continue. Trying to continue from inside the debugger doesn't work.

           Note: if you use GDB, more powerful debugging support is provided by the --vgdb= yes
           or full value. This activates Valgrind's internal gdbserver, which provides
           more-or-less full GDB-style control of the application: insertion of breakpoints,
           continuing from inside GDB, inferior function calls, and much more.

           C Ret or c Ret causes Valgrind not to start a debugger, and not to ask again.

       --db-command=<command> [default: gdb -nw %f %p]
           Specify the debugger to use with the --db-attach command. The default debugger is GDB.
           This option is a template that is expanded by Valgrind at runtime.  %f is replaced
           with the executable's file name and %p is replaced by the process ID of the

           This specifies how Valgrind will invoke the debugger. By default it will use whatever
           GDB is detected at build time, which is usually /usr/bin/gdb. Using this command, you
           can specify some alternative command to invoke the debugger you want to use.

           The command string given can include one or instances of the %p and %f expansions.
           Each instance of %p expands to the PID of the process to be debugged and each instance
           of %f expands to the path to the executable for the process to be debugged.

           Since <command> is likely to contain spaces, you will need to put this entire option
           in quotes to ensure it is correctly handled by the shell.

       --input-fd=<number> [default: 0, stdin]
           When using --db-attach=yes or --gen-suppressions=yes, Valgrind will stop so as to read
           keyboard input from you when each error occurs. By default it reads from the standard
           input (stdin), which is problematic for programs which close stdin. This option allows
           you to specify an alternative file descriptor from which to read input.

       --dsymutil=no|yes [no]
           This option is only relevant when running Valgrind on Mac OS X.

           Mac OS X uses a deferred debug information (debuginfo) linking scheme. When object
           files containing debuginfo are linked into a .dylib or an executable, the debuginfo is
           not copied into the final file. Instead, the debuginfo must be linked manually by
           running dsymutil, a system-provided utility, on the executable or .dylib. The
           resulting combined debuginfo is placed in a directory alongside the executable or
           .dylib, but with the extension .dSYM.

           With --dsymutil=no, Valgrind will detect cases where the .dSYM directory is either
           missing, or is present but does not appear to match the associated executable or
           .dylib, most likely because it is out of date. In these cases, Valgrind will print a
           warning message but take no further action.

           With --dsymutil=yes, Valgrind will, in such cases, automatically run dsymutil as
           necessary to bring the debuginfo up to date. For all practical purposes, if you always
           use --dsymutil=yes, then there is never any need to run dsymutil manually or as part
           of your applications's build system, since Valgrind will run it as necessary.

           Valgrind will not attempt to run dsymutil on any executable or library in /usr/,
           /bin/, /sbin/, /opt/, /sw/, /System/, /Library/ or /Applications/ since dsymutil will
           always fail in such situations. It fails both because the debuginfo for such
           pre-installed system components is not available anywhere, and also because it would
           require write privileges in those directories.

           Be careful when using --dsymutil=yes, since it will cause pre-existing .dSYM
           directories to be silently deleted and re-created. Also note that dsymutil is quite
           slow, sometimes excessively so.

       --max-stackframe=<number> [default: 2000000]
           The maximum size of a stack frame. If the stack pointer moves by more than this amount
           then Valgrind will assume that the program is switching to a different stack.

           You may need to use this option if your program has large stack-allocated arrays.
           Valgrind keeps track of your program's stack pointer. If it changes by more than the
           threshold amount, Valgrind assumes your program is switching to a different stack, and
           Memcheck behaves differently than it would for a stack pointer change smaller than the
           threshold. Usually this heuristic works well. However, if your program allocates large
           structures on the stack, this heuristic will be fooled, and Memcheck will subsequently
           report large numbers of invalid stack accesses. This option allows you to change the
           threshold to a different value.

           You should only consider use of this option if Valgrind's debug output directs you to
           do so. In that case it will tell you the new threshold you should specify.

           In general, allocating large structures on the stack is a bad idea, because you can
           easily run out of stack space, especially on systems with limited memory or which
           expect to support large numbers of threads each with a small stack, and also because
           the error checking performed by Memcheck is more effective for heap-allocated data
           than for stack-allocated data. If you have to use this option, you may wish to
           consider rewriting your code to allocate on the heap rather than on the stack.

       --main-stacksize=<number> [default: use current 'ulimit' value]
           Specifies the size of the main thread's stack.

           To simplify its memory management, Valgrind reserves all required space for the main
           thread's stack at startup. That means it needs to know the required stack size at

           By default, Valgrind uses the current "ulimit" value for the stack size, or 16 MB,
           whichever is lower. In many cases this gives a stack size in the range 8 to 16 MB,
           which almost never overflows for most applications.

           If you need a larger total stack size, use --main-stacksize to specify it. Only set it
           as high as you need, since reserving far more space than you need (that is, hundreds
           of megabytes more than you need) constrains Valgrind's memory allocators and may
           reduce the total amount of memory that Valgrind can use. This is only really of
           significance on 32-bit machines.

           On Linux, you may request a stack of size up to 2GB. Valgrind will stop with a
           diagnostic message if the stack cannot be allocated.

           --main-stacksize only affects the stack size for the program's initial thread. It has
           no bearing on the size of thread stacks, as Valgrind does not allocate those.

           You may need to use both --main-stacksize and --max-stackframe together. It is
           important to understand that --main-stacksize sets the maximum total stack size,
           whilst --max-stackframe specifies the largest size of any one stack frame. You will
           have to work out the --main-stacksize value for yourself (usually, if your
           applications segfaults). But Valgrind will tell you the needed --max-stackframe size,
           if necessary.

           As discussed further in the description of --max-stackframe, a requirement for a large
           stack is a sign of potential portability problems. You are best advised to place all
           large data in heap-allocated memory.


       For tools that use their own version of malloc (e.g. Memcheck and Massif), the following
       options apply.

       --alignment=<number> [default: 8 or 16, depending on the platform]
           By default Valgrind's malloc, realloc, etc, return a block whose starting address is
           8-byte aligned or 16-byte aligned (the value depends on the platform and matches the
           platform default). This option allows you to specify a different alignment. The
           supplied value must be greater than or equal to the default, less than or equal to
           4096, and must be a power of two.


       These options apply to all tools, as they affect certain obscure workings of the Valgrind
       core. Most people won't need to use these.

       --smc-check=<none|stack|all|all-non-file> [default: stack]
           This option controls Valgrind's detection of self-modifying code. If no checking is
           done, if a program executes some code, then overwrites it with new code, and executes
           the new code, Valgrind will continue to execute the translations it made for the old
           code. This will likely lead to incorrect behaviour and/or crashes.

           Valgrind has four levels of self-modifying code detection: no detection, detect
           self-modifying code on the stack (which is used by GCC to implement nested functions),
           detect self-modifying code everywhere, and detect self-modifying code everywhere
           except in file-backed mappings. Note that the default option will catch the vast
           majority of cases. The main case it will not catch is programs such as JIT compilers
           that dynamically generate code and subsequently overwrite part or all of it. Running
           with all will slow Valgrind down noticeably. Running with none will rarely speed
           things up, since very little code gets put on the stack for most programs. The
           VALGRIND_DISCARD_TRANSLATIONS client request is an alternative to --smc-check=all that
           requires more programmer effort but allows Valgrind to run your program faster, by
           telling it precisely when translations need to be re-made.

           --smc-check=all-non-file provides a cheaper but more limited version of
           --smc-check=all. It adds checks to any translations that do not originate from
           file-backed memory mappings. Typical applications that generate code, for example JITs
           in web browsers, generate code into anonymous mmaped areas, whereas the "fixed" code
           of the browser always lives in file-backed mappings.  --smc-check=all-non-file takes
           advantage of this observation, limiting the overhead of checking to code which is
           likely to be JIT generated.

           Some architectures (including ppc32, ppc64 and ARM) require programs which create code
           at runtime to flush the instruction cache in between code generation and first use.
           Valgrind observes and honours such instructions. Hence, on ppc32/Linux, ppc64/Linux
           and ARM/Linux, Valgrind always provides complete, transparent support for
           self-modifying code. It is only on platforms such as x86/Linux, AMD64/Linux,
           x86/Darwin and AMD64/Darwin that you need to use this option.

       --read-var-info=<yes|no> [default: no]
           When enabled, Valgrind will read information about variable types and locations from
           DWARF3 debug info. This slows Valgrind down and makes it use more memory, but for the
           tools that can take advantage of it (Memcheck, Helgrind, DRD) it can result in more
           precise error messages. For example, here are some standard errors issued by Memcheck:

               ==15516== Uninitialised byte(s) found during client check request
               ==15516==    at 0x400633: croak (varinfo1.c:28)
               ==15516==    by 0x4006B2: main (varinfo1.c:55)
               ==15516==  Address 0x60103b is 7 bytes inside data symbol "global_i2"
               ==15516== Uninitialised byte(s) found during client check request
               ==15516==    at 0x400633: croak (varinfo1.c:28)
               ==15516==    by 0x4006BC: main (varinfo1.c:56)
               ==15516==  Address 0x7fefffefc is on thread 1's stack

           And here are the same errors with --read-var-info=yes:

               ==15522== Uninitialised byte(s) found during client check request
               ==15522==    at 0x400633: croak (varinfo1.c:28)
               ==15522==    by 0x4006B2: main (varinfo1.c:55)
               ==15522==  Location 0x60103b is 0 bytes inside global_i2[7],
               ==15522==  a global variable declared at varinfo1.c:41
               ==15522== Uninitialised byte(s) found during client check request
               ==15522==    at 0x400633: croak (varinfo1.c:28)
               ==15522==    by 0x4006BC: main (varinfo1.c:56)
               ==15522==  Location 0x7fefffefc is 0 bytes inside local var "local"
               ==15522==  declared at varinfo1.c:46, in frame #1 of thread 1

       --vgdb-poll=<number> [default: 5000]
           As part of its main loop, the Valgrind scheduler will poll to check if some activity
           (such as an external command or some input from a gdb) has to be handled by gdbserver.
           This activity poll will be done after having run the given number of basic blocks (or
           slightly more than the given number of basic blocks). This poll is quite cheap so the
           default value is set relatively low. You might further decrease this value if vgdb
           cannot use ptrace system call to interrupt Valgrind if all threads are (most of the
           time) blocked in a system call.

       --vgdb-shadow-registers=no|yes [default: no]
           When activated, gdbserver will expose the Valgrind shadow registers to GDB. With this,
           the value of the Valgrind shadow registers can be examined or changed using GDB.
           Exposing shadow registers only works with GDB version 7.1 or later.

       --vgdb-prefix=<prefix> [default: /tmp/vgdb-pipe]
           To communicate with gdb/vgdb, the Valgrind gdbserver creates 3 files (2 named FIFOs
           and a mmap shared memory file). The prefix option controls the directory and prefix
           for the creation of these files.

       --run-libc-freeres=<yes|no> [default: yes]
           This option is only relevant when running Valgrind on Linux.

           The GNU C library (, which is used by all programs, may allocate memory for
           its own uses. Usually it doesn't bother to free that memory when the program ends—
           there would be no point, since the Linux kernel reclaims all process resources when a
           process exits anyway, so it would just slow things down.

           The glibc authors realised that this behaviour causes leak checkers, such as Valgrind,
           to falsely report leaks in glibc, when a leak check is done at exit. In order to avoid
           this, they provided a routine called __libc_freeres specifically to make glibc release
           all memory it has allocated. Memcheck therefore tries to run __libc_freeres at exit.

           Unfortunately, in some very old versions of glibc, __libc_freeres is sufficiently
           buggy to cause segmentation faults. This was particularly noticeable on Red Hat 7.1.
           So this option is provided in order to inhibit the run of __libc_freeres. If your
           program seems to run fine on Valgrind, but segfaults at exit, you may find that
           --run-libc-freeres=no fixes that, although at the cost of possibly falsely reporting
           space leaks in

           Pass miscellaneous hints to Valgrind which slightly modify the simulated behaviour in
           nonstandard or dangerous ways, possibly to help the simulation of strange features. By
           default no hints are enabled. Use with caution! Currently known hints are:

           ·   lax-ioctls: Be very lax about ioctl handling; the only assumption is that the size
               is correct. Doesn't require the full buffer to be initialized when writing.
               Without this, using some device drivers with a large number of strange ioctl
               commands becomes very tiresome.

           ·   enable-inner: Enable some special magic needed when the program being run is
               itself Valgrind.

           ·   fuse-compatible: Enable special handling for certain system calls that may block
               in a FUSE file-system. This may be necessary when running Valgrind on a
               multi-threaded program that uses one thread to manage a FUSE file-system and
               another thread to access that file-system.

           Handle system calls and ioctls arising from minor variants of the default kernel for
           this platform. This is useful for running on hacked kernels or with kernel modules
           which support nonstandard ioctls, for example. Use with caution. If you don't
           understand what this option does then you almost certainly don't need it. Currently
           known variants are:

           ·   bproc: Support the sys_broc system call on x86. This is for running on BProc,
               which is a minor variant of standard Linux which is sometimes used for building

       --show-emwarns=<yes|no> [default: no]
           When enabled, Valgrind will emit warnings about its CPU emulation in certain cases.
           These are usually not interesting.

           When a shared object whose soname matches sonamepatt is loaded into the process,
           examine all the text symbols it exports. If none of those match fnnamepatt, print an
           error message and abandon the run. This makes it possible to ensure that the run does
           not continue unless a given shared object contains a particular function name.

           Both sonamepatt and fnnamepatt can be written using the usual ?  and * wildcards. For
           example: ":**:foo?bar". You may use characters other than a colon to separate
           the two patterns. It is only important that the first character and the separator
           character are the same. For example, the above example could also be written
           "Q**Qfoo?bar". Multiple
            --require-text-symbol flags are allowed, in which case shared objects that are loaded
           into the process will be checked against all of them.

           The purpose of this is to support reliable usage of marked-up libraries. For example,
           suppose we have a version of GCC's which has been marked up with
           annotations to support Helgrind. It is only too easy and confusing to load the wrong,
           un-annotated into the application. So the idea is: add a text symbol in the
           marked-up library, for example annotated_for_helgrind_3_6, and then give the flag
           --require-text-symbol=:*libgomp*so*:annotated_for_helgrind_3_6 so that when
           is loaded, Valgrind scans its symbol table, and if the symbol isn't present the run is
           aborted, rather than continuing silently with the un-marked-up library. Note that you
           should put the entire flag in quotes to stop shells expanding up the * and ?


       There are also some options for debugging Valgrind itself. You shouldn't need to use them
       in the normal run of things. If you wish to see the list, use the --help-debug option.


       --leak-check=<no|summary|yes|full> [default: summary]
           When enabled, search for memory leaks when the client program finishes. If set to
           summary, it says how many leaks occurred. If set to full or yes, it also gives details
           of each individual leak.

       --show-possibly-lost=<yes|no> [default: yes]
           When disabled, the memory leak detector will not show "possibly lost" blocks.

       --leak-resolution=<low|med|high> [default: high]
           When doing leak checking, determines how willing Memcheck is to consider different
           backtraces to be the same for the purposes of merging multiple leaks into a single
           leak report. When set to low, only the first two entries need match. When med, four
           entries have to match. When high, all entries need to match.

           For hardcore leak debugging, you probably want to use --leak-resolution=high together
           with --num-callers=40 or some such large number.

           Note that the --leak-resolution setting does not affect Memcheck's ability to find
           leaks. It only changes how the results are presented.

       --show-reachable=<yes|no> [default: no]
           When disabled, the memory leak detector only shows "definitely lost" and "possibly
           lost" blocks. When enabled, the leak detector also shows "reachable" and "indirectly
           lost" blocks. (In other words, it shows all blocks, except suppressed ones, so
           --show-all would be a better name for it.)

       --undef-value-errors=<yes|no> [default: yes]
           Controls whether Memcheck reports uses of undefined value errors. Set this to no if
           you don't want to see undefined value errors. It also has the side effect of speeding
           up Memcheck somewhat.

       --track-origins=<yes|no> [default: no]
           Controls whether Memcheck tracks the origin of uninitialised values. By default, it
           does not, which means that although it can tell you that an uninitialised value is
           being used in a dangerous way, it cannot tell you where the uninitialised value came
           from. This often makes it difficult to track down the root problem.

           When set to yes, Memcheck keeps track of the origins of all uninitialised values.
           Then, when an uninitialised value error is reported, Memcheck will try to show the
           origin of the value. An origin can be one of the following four places: a heap block,
           a stack allocation, a client request, or miscellaneous other sources (eg, a call to

           For uninitialised values originating from a heap block, Memcheck shows where the block
           was allocated. For uninitialised values originating from a stack allocation, Memcheck
           can tell you which function allocated the value, but no more than that -- typically it
           shows you the source location of the opening brace of the function. So you should
           carefully check that all of the function's local variables are initialised properly.

           Performance overhead: origin tracking is expensive. It halves Memcheck's speed and
           increases memory use by a minimum of 100MB, and possibly more. Nevertheless it can
           drastically reduce the effort required to identify the root cause of uninitialised
           value errors, and so is often a programmer productivity win, despite running more

           Accuracy: Memcheck tracks origins quite accurately. To avoid very large space and time
           overheads, some approximations are made. It is possible, although unlikely, that
           Memcheck will report an incorrect origin, or not be able to identify any origin.

           Note that the combination --track-origins=yes and --undef-value-errors=no is
           nonsensical. Memcheck checks for and rejects this combination at startup.

       --partial-loads-ok=<yes|no> [default: no]
           Controls how Memcheck handles word-sized, word-aligned loads from addresses for which
           some bytes are addressable and others are not. When yes, such loads do not produce an
           address error. Instead, loaded bytes originating from illegal addresses are marked as
           uninitialised, and those corresponding to legal addresses are handled in the normal

           When no, loads from partially invalid addresses are treated the same as loads from
           completely invalid addresses: an illegal-address error is issued, and the resulting
           bytes are marked as initialised.

           Note that code that behaves in this way is in violation of the the ISO C/C++
           standards, and should be considered broken. If at all possible, such code should be
           fixed. This option should be used only as a last resort.

       --freelist-vol=<number> [default: 20000000]
           When the client program releases memory using free (in C) or delete (C++), that memory
           is not immediately made available for re-allocation. Instead, it is marked
           inaccessible and placed in a queue of freed blocks. The purpose is to defer as long as
           possible the point at which freed-up memory comes back into circulation. This
           increases the chance that Memcheck will be able to detect invalid accesses to blocks
           for some significant period of time after they have been freed.

           This option specifies the maximum total size, in bytes, of the blocks in the queue.
           The default value is twenty million bytes. Increasing this increases the total amount
           of memory used by Memcheck but may detect invalid uses of freed blocks which would
           otherwise go undetected.

       --freelist-big-blocks=<number> [default: 1000000]
           When making blocks from the queue of freed blocks available for re-allocation,
           Memcheck will in priority re-circulate the blocks with a size greater or equal to
           --freelist-big-blocks. This ensures that freeing big blocks (in particular freeing
           blocks bigger than --freelist-vol) does not immediately lead to a re-circulation of
           all (or a lot of) the small blocks in the free list. In other words, this option
           increases the likelihood to discover dangling pointers for the "small" blocks, even
           when big blocks are freed.

           Setting a value of 0 means that all the blocks are re-circulated in a FIFO order.

       --workaround-gcc296-bugs=<yes|no> [default: no]
           When enabled, assume that reads and writes some small distance below the stack pointer
           are due to bugs in GCC 2.96, and does not report them. The "small distance" is 256
           bytes by default. Note that GCC 2.96 is the default compiler on some ancient Linux
           distributions (RedHat 7.X) and so you may need to use this option. Do not use it if
           you do not have to, as it can cause real errors to be overlooked. A better alternative
           is to use a more recent GCC in which this bug is fixed.

           You may also need to use this option when working with GCC 3.X or 4.X on 32-bit
           PowerPC Linux. This is because GCC generates code which occasionally accesses below
           the stack pointer, particularly for floating-point to/from integer conversions. This
           is in violation of the 32-bit PowerPC ELF specification, which makes no provision for
           locations below the stack pointer to be accessible.

           Any ranges listed in this option (and multiple ranges can be specified, separated by
           commas) will be ignored by Memcheck's addressability checking.

           Fills blocks allocated by malloc, new, etc, but not by calloc, with the specified
           byte. This can be useful when trying to shake out obscure memory corruption problems.
           The allocated area is still regarded by Memcheck as undefined -- this option only
           affects its contents.

           Fills blocks freed by free, delete, etc, with the specified byte value. This can be
           useful when trying to shake out obscure memory corruption problems. The freed area is
           still regarded by Memcheck as not valid for access -- this option only affects its


       --I1=<size>,<associativity>,<line size>
           Specify the size, associativity and line size of the level 1 instruction cache.

       --D1=<size>,<associativity>,<line size>
           Specify the size, associativity and line size of the level 1 data cache.

       --LL=<size>,<associativity>,<line size>
           Specify the size, associativity and line size of the last-level cache.

       --cache-sim=no|yes [yes]
           Enables or disables collection of cache access and miss counts.

       --branch-sim=no|yes [no]
           Enables or disables collection of branch instruction and misprediction counts. By
           default this is disabled as it slows Cachegrind down by approximately 25%. Note that
           you cannot specify --cache-sim=no and --branch-sim=no together, as that would leave
           Cachegrind with no information to collect.

           Write the profile data to file rather than to the default output file,
           cachegrind.out.<pid>. The %p and %q format specifiers can be used to embed the process
           ID and/or the contents of an environment variable in the name, as is the case for the
           core option --log-file.


           Write the profile data to file rather than to the default output file,
           callgrind.out.<pid>. The %p and %q format specifiers can be used to embed the process
           ID and/or the contents of an environment variable in the name, as is the case for the
           core option --log-file. When multiple dumps are made, the file name is modified
           further; see below.

       --dump-line=<no|yes> [default: yes]
           This specifies that event counting should be performed at source line granularity.
           This allows source annotation for sources which are compiled with debug information

       --dump-instr=<no|yes> [default: no]
           This specifies that event counting should be performed at per-instruction granularity.
           This allows for assembly code annotation. Currently the results can only be displayed
           by KCachegrind.

       --compress-strings=<no|yes> [default: yes]
           This option influences the output format of the profile data. It specifies whether
           strings (file and function names) should be identified by numbers. This shrinks the
           file, but makes it more difficult for humans to read (which is not recommended in any

       --compress-pos=<no|yes> [default: yes]
           This option influences the output format of the profile data. It specifies whether
           numerical positions are always specified as absolute values or are allowed to be
           relative to previous numbers. This shrinks the file size.

       --combine-dumps=<no|yes> [default: no]
           When enabled, when multiple profile data parts are to be generated these parts are
           appended to the same output file. Not recommended.

       --dump-every-bb=<count> [default: 0, never]
           Dump profile data every count basic blocks. Whether a dump is needed is only checked
           when Valgrind's internal scheduler is run. Therefore, the minimum setting useful is
           about 100000. The count is a 64-bit value to make long dump periods possible.

           Dump when entering function.

           Zero all costs when entering function.

           Dump when leaving function.

       --instr-atstart=<yes|no> [default: yes]
           Specify if you want Callgrind to start simulation and profiling from the beginning of
           the program. When set to no, Callgrind will not be able to collect any information,
           including calls, but it will have at most a slowdown of around 4, which is the minimum
           Valgrind overhead. Instrumentation can be interactively enabled via callgrind_control
           -i on.

           Note that the resulting call graph will most probably not contain main, but will
           contain all the functions executed after instrumentation was enabled. Instrumentation
           can also programatically enabled/disabled. See the Callgrind include file callgrind.h
           for the macro you have to use in your source code.

           For cache simulation, results will be less accurate when switching on instrumentation
           later in the program run, as the simulator starts with an empty cache at that moment.
           Switch on event collection later to cope with this error.

       --collect-atstart=<yes|no> [default: yes]
           Specify whether event collection is enabled at beginning of the profile run.

           To only look at parts of your program, you have two possibilities:

            1. Zero event counters before entering the program part you want to profile, and dump
               the event counters to a file after leaving that program part.

            2. Switch on/off collection state as needed to only see event counters happening
               while inside of the program part you want to profile.

           The second option can be used if the program part you want to profile is called many
           times. Option 1, i.e. creating a lot of dumps is not practical here.

           Collection state can be toggled at entry and exit of a given function with the option
           --toggle-collect. If you use this option, collection state should be disabled at the
           beginning. Note that the specification of --toggle-collect implicitly sets

           Collection state can be toggled also by inserting the client request
           CALLGRIND_TOGGLE_COLLECT ; at the needed code positions.

           Toggle collection on entry/exit of function.

       --collect-jumps=<no|yes> [default: no]
           This specifies whether information for (conditional) jumps should be collected. As
           above, callgrind_annotate currently is not able to show you the data. You have to use
           KCachegrind to get jump arrows in the annotated code.

       --collect-systime=<no|yes> [default: no]
           This specifies whether information for system call times should be collected.

       --collect-bus=<no|yes> [default: no]
           This specifies whether the number of global bus events executed should be collected.
           The event type "Ge" is used for these events.

       --cache-sim=<yes|no> [default: no]
           Specify if you want to do full cache simulation. By default, only instruction read
           accesses will be counted ("Ir"). With cache simulation, further event counters are
           enabled: Cache misses on instruction reads ("I1mr"/"ILmr"), data read accesses ("Dr")
           and related cache misses ("D1mr"/"DLmr"), data write accesses ("Dw") and related cache
           misses ("D1mw"/"DLmw"). For more information, see ???.

       --branch-sim=<yes|no> [default: no]
           Specify if you want to do branch prediction simulation. Further event counters are
           enabled: Number of executed conditional branches and related predictor misses
           ("Bc"/"Bcm"), executed indirect jumps and related misses of the jump address predictor


       --free-is-write=no|yes [default: no]
           When enabled (not the default), Helgrind treats freeing of heap memory as if the
           memory was written immediately before the free. This exposes races where memory is
           referenced by one thread, and freed by another, but there is no observable
           synchronisation event to ensure that the reference happens before the free.

           This functionality is new in Valgrind 3.7.0, and is regarded as experimental. It is
           not enabled by default because its interaction with custom memory allocators is not
           well understood at present. User feedback is welcomed.

       --track-lockorders=no|yes [default: yes]
           When enabled (the default), Helgrind performs lock order consistency checking. For
           some buggy programs, the large number of lock order errors reported can become
           annoying, particularly if you're only interested in race errors. You may therefore
           find it helpful to disable lock order checking.

       --history-level=none|approx|full [default: full]
           --history-level=full (the default) causes Helgrind collects enough information about
           "old" accesses that it can produce two stack traces in a race report -- both the stack
           trace for the current access, and the trace for the older, conflicting access.

           Collecting such information is expensive in both speed and memory, particularly for
           programs that do many inter-thread synchronisation events (locks, unlocks, etc).
           Without such information, it is more difficult to track down the root causes of races.
           Nonetheless, you may not need it in situations where you just want to check for the
           presence or absence of races, for example, when doing regression testing of a
           previously race-free program.

           --history-level=none is the opposite extreme. It causes Helgrind not to collect any
           information about previous accesses. This can be dramatically faster than

           --history-level=approx provides a compromise between these two extremes. It causes
           Helgrind to show a full trace for the later access, and approximate information
           regarding the earlier access. This approximate information consists of two stacks, and
           the earlier access is guaranteed to have occurred somewhere between program points
           denoted by the two stacks. This is not as useful as showing the exact stack for the
           previous access (as --history-level=full does), but it is better than nothing, and it
           is almost as fast as --history-level=none.

       --conflict-cache-size=N [default: 1000000]
           This flag only has any effect at --history-level=full.

           Information about "old" conflicting accesses is stored in a cache of limited size,
           with LRU-style management. This is necessary because it isn't practical to store a
           stack trace for every single memory access made by the program. Historical information
           on not recently accessed locations is periodically discarded, to free up space in the

           This option controls the size of the cache, in terms of the number of different memory
           addresses for which conflicting access information is stored. If you find that
           Helgrind is showing race errors with only one stack instead of the expected two
           stacks, try increasing this value.

           The minimum value is 10,000 and the maximum is 30,000,000 (thirty times the default
           value). Increasing the value by 1 increases Helgrind's memory requirement by very
           roughly 100 bytes, so the maximum value will easily eat up three extra gigabytes or so
           of memory.

       --check-stack-refs=no|yes [default: yes]
           By default Helgrind checks all data memory accesses made by your program. This flag
           enables you to skip checking for accesses to thread stacks (local variables). This can
           improve performance, but comes at the cost of missing races on stack-allocated data.


       --check-stack-var=<yes|no> [default: no]
           Controls whether DRD detects data races on stack variables. Verifying stack variables
           is disabled by default because most programs do not share stack variables over

       --exclusive-threshold=<n> [default: off]
           Print an error message if any mutex or writer lock has been held longer than the time
           specified in milliseconds. This option enables the detection of lock contention.

       --join-list-vol=<n> [default: 10]
           Data races that occur between a statement at the end of one thread and another thread
           can be missed if memory access information is discarded immediately after a thread has
           been joined. This option allows to specify for how many joined threads memory access
           information should be retained.

        --first-race-only=<yes|no> [default: no]
           Whether to report only the first data race that has been detected on a memory location
           or all data races that have been detected on a memory location.

        --free-is-write=<yes|no> [default: no]
           Whether to report races between accessing memory and freeing memory. Enabling this
           option may cause DRD to run slightly slower. Notes:

           ·   Don't enable this option when using custom memory allocators that use the
               VG_USERREQ__MALLOCLIKE_BLOCK and VG_USERREQ__FREELIKE_BLOCK because that would
               result in false positives.

           ·   Don't enable this option when using reference-counted objects because that will
               result in false positives, even when that code has been annotated properly with
               ANNOTATE_HAPPENS_BEFORE and ANNOTATE_HAPPENS_AFTER. See e.g. the output of the
               following command for an example: valgrind --tool=drd --free-is-write=yes

        --report-signal-unlocked=<yes|no> [default: yes]
           Whether to report calls to pthread_cond_signal and pthread_cond_broadcast where the
           mutex associated with the signal through pthread_cond_wait or
           pthread_cond_timed_waitis not locked at the time the signal is sent. Sending a signal
           without holding a lock on the associated mutex is a common programming error which can
           cause subtle race conditions and unpredictable behavior. There exist some uncommon
           synchronization patterns however where it is safe to send a signal without holding a
           lock on the associated mutex.

       --segment-merging=<yes|no> [default: yes]
           Controls segment merging. Segment merging is an algorithm to limit memory usage of the
           data race detection algorithm. Disabling segment merging may improve the accuracy of
           the so-called 'other segments' displayed in race reports but can also trigger an out
           of memory error.

       --segment-merging-interval=<n> [default: 10]
           Perform segment merging only after the specified number of new segments have been
           created. This is an advanced configuration option that allows to choose whether to
           minimize DRD's memory usage by choosing a low value or to let DRD run faster by
           choosing a slightly higher value. The optimal value for this parameter depends on the
           program being analyzed. The default value works well for most programs.

       --shared-threshold=<n> [default: off]
           Print an error message if a reader lock has been held longer than the specified time
           (in milliseconds). This option enables the detection of lock contention.

       --show-confl-seg=<yes|no> [default: yes]
           Show conflicting segments in race reports. Since this information can help to find the
           cause of a data race, this option is enabled by default. Disabling this option makes
           the output of DRD more compact.

       --show-stack-usage=<yes|no> [default: no]
           Print stack usage at thread exit time. When a program creates a large number of
           threads it becomes important to limit the amount of virtual memory allocated for
           thread stacks. This option makes it possible to observe how much stack memory has been
           used by each thread of the the client program. Note: the DRD tool itself allocates
           some temporary data on the client thread stack. The space necessary for this temporary
           data must be allocated by the client program when it allocates stack memory, but is
           not included in stack usage reported by DRD.

       --trace-addr=<address> [default: none]
           Trace all load and store activity for the specified address. This option may be
           specified more than once.

       --trace-alloc=<yes|no> [default: no]
           Trace all memory allocations and deallocations. May produce a huge amount of output.

       --trace-barrier=<yes|no> [default: no]
           Trace all barrier activity.

       --trace-cond=<yes|no> [default: no]
           Trace all condition variable activity.

       --trace-fork-join=<yes|no> [default: no]
           Trace all thread creation and all thread termination events.

       --trace-hb=<yes|no> [default: no]
           Trace execution of the ANNOTATE_HAPPENS_BEFORE(), ANNOTATE_HAPPENS_AFTER() and
           ANNOTATE_HAPPENS_DONE() client requests.

       --trace-mutex=<yes|no> [default: no]
           Trace all mutex activity.

       --trace-rwlock=<yes|no> [default: no]
           Trace all reader-writer lock activity.

       --trace-semaphore=<yes|no> [default: no]
           Trace all semaphore activity.


       --heap=<yes|no> [default: yes]
           Specifies whether heap profiling should be done.

       --heap-admin=<size> [default: 8]
           If heap profiling is enabled, gives the number of administrative bytes per block to
           use. This should be an estimate of the average, since it may vary. For example, the
           allocator used by glibc on Linux requires somewhere between 4 to 15 bytes per block,
           depending on various factors. That allocator also requires admin space for freed
           blocks, but Massif cannot account for this.

       --stacks=<yes|no> [default: no]
           Specifies whether stack profiling should be done. This option slows Massif down
           greatly, and so is off by default. Note that Massif assumes that the main stack has
           size zero at start-up. This is not true, but doing otherwise accurately is difficult.
           Furthermore, starting at zero better indicates the size of the part of the main stack
           that a user program actually has control over.

       --pages-as-heap=<yes|no> [default: no]
           Tells Massif to profile memory at the page level rather than at the malloc'd block
           level. See above for details.

       --depth=<number> [default: 30]
           Maximum depth of the allocation trees recorded for detailed snapshots. Increasing it
           will make Massif run somewhat more slowly, use more memory, and produce bigger output

           Functions specified with this option will be treated as though they were a heap
           allocation function such as malloc. This is useful for functions that are wrappers to
           malloc or new, which can fill up the allocation trees with uninteresting information.
           This option can be specified multiple times on the command line, to name multiple

           Note that the named function will only be treated this way if it is the top entry in a
           stack trace, or just below another function treated this way. For example, if you have
           a function malloc1 that wraps malloc, and malloc2 that wraps malloc1, just specifying
           --alloc-fn=malloc2 will have no effect. You need to specify --alloc-fn=malloc1 as
           well. This is a little inconvenient, but the reason is that checking for allocation
           functions is slow, and it saves a lot of time if Massif can stop looking through the
           stack trace entries as soon as it finds one that doesn't match rather than having to
           continue through all the entries.

           Note that C++ names are demangled. Note also that overloaded C++ names must be written
           in full. Single quotes may be necessary to prevent the shell from breaking them up.
           For example:

               --alloc-fn='operator new(unsigned, std::nothrow_t const&)'

           Any direct heap allocation (i.e. a call to malloc, new, etc, or a call to a function
           named by an --alloc-fn option) that occurs in a function specified by this option will
           be ignored. This is mostly useful for testing purposes. This option can be specified
           multiple times on the command line, to name multiple functions.

           Any realloc of an ignored block will also be ignored, even if the realloc call does
           not occur in an ignored function. This avoids the possibility of negative heap sizes
           if ignored blocks are shrunk with realloc.

           The rules for writing C++ function names are the same as for --alloc-fn above.

       --threshold=<m.n> [default: 1.0]
           The significance threshold for heap allocations, as a percentage of total memory size.
           Allocation tree entries that account for less than this will be aggregated. Note that
           this should be specified in tandem with ms_print's option of the same name.

       --peak-inaccuracy=<m.n> [default: 1.0]
           Massif does not necessarily record the actual global memory allocation peak; by
           default it records a peak only when the global memory allocation size exceeds the
           previous peak by at least 1.0%. This is because there can be many local allocation
           peaks along the way, and doing a detailed snapshot for every one would be expensive
           and wasteful, as all but one of them will be later discarded. This inaccuracy can be
           changed (even to 0.0%) via this option, but Massif will run drastically slower as the
           number approaches zero.

       --time-unit=<i|ms|B> [default: i]
           The time unit used for the profiling. There are three possibilities: instructions
           executed (i), which is good for most cases; real (wallclock) time (ms, i.e.
           milliseconds), which is sometimes useful; and bytes allocated/deallocated on the heap
           and/or stack (B), which is useful for very short-run programs, and for testing
           purposes, because it is the most reproducible across different machines.

       --detailed-freq=<n> [default: 10]
           Frequency of detailed snapshots. With --detailed-freq=1, every snapshot is detailed.

       --max-snapshots=<n> [default: 100]
           The maximum number of snapshots recorded. If set to N, for all programs except very
           short-running ones, the final number of snapshots will be between N/2 and N.

       --massif-out-file=<file> [default: massif.out.%p]
           Write the profile data to file rather than to the default output file,
           massif.out.<pid>. The %p and %q format specifiers can be used to embed the process ID
           and/or the contents of an environment variable in the name, as is the case for the
           core option --log-file.


       <xi:include></xi:include>.SH "BBV OPTIONS"

       --bb-out-file=<name> [default: bb.out.%p]
           This option selects the name of the basic block vector file. The %p and %q format
           specifiers can be used to embed the process ID and/or the contents of an environment
           variable in the name, as is the case for the core option --log-file.

       --pc-out-file=<name> [default: pc.out.%p]
           This option selects the name of the PC file. This file holds program counter addresses
           and function name info for the various basic blocks. This can be used in conjunction
           with the basic block vector file to fast-forward via function names instead of just
           instruction counts. The %p and %q format specifiers can be used to embed the process
           ID and/or the contents of an environment variable in the name, as is the case for the
           core option --log-file.

       --interval-size=<number> [default: 100000000]
           This option selects the size of the interval to use. The default is 100 million
           instructions, which is a commonly used value. Other sizes can be used; smaller
           intervals can help programs with finer-grained phases. However smaller interval size
           can lead to accuracy issues due to warm-up effects (When fast-forwarding the various
           architectural features will be un-initialized, and it will take some number of
           instructions before they "warm up" to the state a full simulation would be at without
           the fast-forwarding. Large interval sizes tend to mitigate this.)

       --instr-count-only [default: no]
           This option tells the tool to only display instruction count totals, and to not
           generate the actual basic block vector file. This is useful for debugging, and for
           gathering instruction count info without generating the large basic block vector


       --basic-counts=<no|yes> [default: yes]
           When enabled, Lackey prints the following statistics and information about the
           execution of the client program:

            1. The number of calls to the function specified by the --fnname option (the default
               is main). If the program has had its symbols stripped, the count will always be

            2. The number of conditional branches encountered and the number and proportion of
               those taken.

            3. The number of superblocks entered and completed by the program. Note that due to
               optimisations done by the JIT, this is not at all an accurate value.

            4. The number of guest (x86, amd64, ppc, etc.) instructions and IR statements
               executed. IR is Valgrind's RISC-like intermediate representation via which all
               instrumentation is done.

            5. Ratios between some of these counts.

            6. The exit code of the client program.

       --detailed-counts=<no|yes> [default: no]
           When enabled, Lackey prints a table containing counts of loads, stores and ALU
           operations, differentiated by their IR types. The IR types are identified by their IR
           name ("I1", "I8", ... "I128", "F32", "F64", and "V128").

       --trace-mem=<no|yes> [default: no]
           When enabled, Lackey prints the size and address of almost every memory access made by
           the program. See the comments at the top of the file lackey/lk_main.c for details
           about the output format, how it works, and inaccuracies in the address trace. Note
           that this option produces immense amounts of output.

       --trace-superblocks=<no|yes> [default: no]
           When enabled, Lackey prints out the address of every superblock (a single entry,
           multiple exit, linear chunk of code) executed by the program. This is primarily of
           interest to Valgrind developers. See the comments at the top of the file
           lackey/lk_main.c for details about the output format. Note that this option produces
           large amounts of output.

       --fnname=<name> [default: main]
           Changes the function for which calls are counted when --basic-counts=yes is specified.


       cg_annotate(1), callgrind_annotate(1), callgrind_control(1), ms_print(1),
       $INSTALL/share/doc/valgrind/html/index.html or


       The Valgrind developers.

       This manpage was written by Andres Roldan <> and the Valgrind