Provided by: memtester_4.3.0-3_i386 bug

NAME

       memtester - stress test to find memory subsystem faults.

SYNOPSIS

       memtester [-p PHYSADDR [-d DEVICE]] <MEMORY> [ITERATIONS]

DESCRIPTION

       memtester  is  an  effective  userspace  tester  for stress-testing the
       memory subsystem.  It is very effective  at  finding  intermittent  and
       non-deterministic  faults.   Note that problems in other hardware areas
       (overheating CPU, out-of-specification power supply,  etc.)  can  cause
       intermittent memory faults, so it is still up to you to determine where
       the fault lies through normal hardware diagnostic procedures; memtester
       just helps you determine whether a problem exists.

       memtester  will  malloc(3) the amount of memory specified, if possible.
       If this fails, it will decrease the amount of memory requested until it
       succeeds.   It  will then attempt to mlock(3) this memory; if it cannot
       do so, testing will be slower and much less effective.   Run  memtester
       as root so that it can mlock the memory it tests.

       Note  that the maximum amount of memory that memtester can test will be
       less than the total amount of  memory  installed  in  the  system;  the
       operating  system,  libraries, and other system limits take some of the
       available memory.  memtester is also limited to the  amount  of  memory
       available  to  a  single  process; for example, on 32-bit machines with
       more than 4GB of memory, memtester is still limited to less than 4GB.

       Note that it is up to you to  know  how  much  memory  you  can  safely
       allocate  for  testing.  If you attempt to allocate more memory than is
       available,  memtester  should  figure  that  out,  reduce  the   amount
       slightly,   and  try  again.   However,  this  can  lead  to  memtester
       successfully allocating and mlocking essentially all free memory on the
       system  --  if  other  programs are running, this can lead to excessive
       swapping and slowing the system down to the point that it is  difficult
       to  use.   If  the  system  allows  allocation  of  more memory than is
       actually available (overcommit), it may lead to a deadlock,  where  the
       system  halts.  If the system has an out-of-memory process killer (like
       Linux), memtester or another process may be killed by the OOM killer.

       So choose wisely.

OPTIONS

       -p PHYSADDR
              tells memtester to test a specific region of memory starting  at
              physical address PHYSADDR (given in hex), by mmap(2)ing a device
              specified by the -d option  (below,  or  /dev/mem  by  default).
              This  is  mostly  of  use  to  hardware  developers, for testing
              memory-mapped I/O devices and similar.   Note  that  the  memory
              region  will be overwritten during testing, so it is not safe to
              specify memory which is allocated for the system  or  for  other
              applications;  doing  so  will  cause  them  to  crash.   If you
              absolutely must test a  particular  region  of  actual  physical
              memory,  arrange  to  have  that  memory  allocated by your test
              software,  and  hold  it  in  this  allocated  state,  then  run
              memtester on it with this option.

       MEMORY the  amount  of  memory  to  allocate  and test, in megabytes by
              default.  You can include a suffix of B, K, M, or G to  indicate
              bytes, kilobytes, megabytes, or gigabytes respectively.

       ITERATIONS
              (optional)  number  of  loops  to  iterate  through.  Default is
              infinite.

ENVIRONMENT

       If the  environment  variable  MEMTESTER_TEST_MASK  is  set,  memtester
       treats  the  value  as  a  bitmask of which tests (other than the stuck
       address test) to run.  The value can be specified in decimal, in  octal
       (with  a  leading  0),  or  in  hexadecimal  (with  a leading 0x).  The
       specific bit values corresponding to particular tests may  change  from
       release  to  release;  consult  the list of tests in the source for the
       appropriate index values for the version of memtester you are  running.
       Note  that  skipping  some  tests  will  reduce  the  time it takes for
       memtester to run, but also reduce memtester's effectiveness.

NOTE

       memtester must be run with  root  privileges  to  mlock(3)  its  pages.
       Testing  memory  without locking the pages in place is mostly pointless
       and slow.

EXIT CODE

       memtester's exit code is 0 when everything works properly.   Otherwise,
       it is the logical OR of the following values:

       x01    error allocating or locking memory, or invocation error

       x02    error during stuck address test

       x04    error during one of the other tests

AUTHOR

       Written by Charles Cazabon.

REPORTING BUGS

       Report bugs to <charlesc-memtester-bugs@pyropus.ca>.

COPYRIGHT

       Copyright © 2001-2012 Charles Cazabon
       This  is  free  software;  see the file COPYING for copying conditions.
       There is NO warranty; not even for MERCHANTABILITY  or  FITNESS  FOR  A
       PARTICULAR PURPOSE.