Provided by: libhwloc-doc_1.8-1ubuntu1.14.04.1_all 
NAME
Memory binding -
Enumerations
enum hwloc_membind_policy_t { HWLOC_MEMBIND_DEFAULT, HWLOC_MEMBIND_FIRSTTOUCH,
HWLOC_MEMBIND_BIND, HWLOC_MEMBIND_INTERLEAVE, HWLOC_MEMBIND_REPLICATE,
HWLOC_MEMBIND_NEXTTOUCH, HWLOC_MEMBIND_MIXED }
enum hwloc_membind_flags_t { HWLOC_MEMBIND_PROCESS, HWLOC_MEMBIND_THREAD,
HWLOC_MEMBIND_STRICT, HWLOC_MEMBIND_MIGRATE, HWLOC_MEMBIND_NOCPUBIND }
Functions
int hwloc_set_membind_nodeset (hwloc_topology_t topology, hwloc_const_nodeset_t nodeset,
hwloc_membind_policy_t policy, int flags)
int hwloc_set_membind (hwloc_topology_t topology, hwloc_const_cpuset_t cpuset,
hwloc_membind_policy_t policy, int flags)
int hwloc_get_membind_nodeset (hwloc_topology_t topology, hwloc_nodeset_t nodeset,
hwloc_membind_policy_t *policy, int flags)
int hwloc_get_membind (hwloc_topology_t topology, hwloc_cpuset_t cpuset,
hwloc_membind_policy_t *policy, int flags)
int hwloc_set_proc_membind_nodeset (hwloc_topology_t topology, hwloc_pid_t pid,
hwloc_const_nodeset_t nodeset, hwloc_membind_policy_t policy, int flags)
int hwloc_set_proc_membind (hwloc_topology_t topology, hwloc_pid_t pid,
hwloc_const_cpuset_t cpuset, hwloc_membind_policy_t policy, int flags)
int hwloc_get_proc_membind_nodeset (hwloc_topology_t topology, hwloc_pid_t pid,
hwloc_nodeset_t nodeset, hwloc_membind_policy_t *policy, int flags)
int hwloc_get_proc_membind (hwloc_topology_t topology, hwloc_pid_t pid, hwloc_cpuset_t
cpuset, hwloc_membind_policy_t *policy, int flags)
int hwloc_set_area_membind_nodeset (hwloc_topology_t topology, const void *addr, size_t
len, hwloc_const_nodeset_t nodeset, hwloc_membind_policy_t policy, int flags)
int hwloc_set_area_membind (hwloc_topology_t topology, const void *addr, size_t len,
hwloc_const_cpuset_t cpuset, hwloc_membind_policy_t policy, int flags)
int hwloc_get_area_membind_nodeset (hwloc_topology_t topology, const void *addr, size_t
len, hwloc_nodeset_t nodeset, hwloc_membind_policy_t *policy, int flags)
int hwloc_get_area_membind (hwloc_topology_t topology, const void *addr, size_t len,
hwloc_cpuset_t cpuset, hwloc_membind_policy_t *policy, int flags)
void * hwloc_alloc (hwloc_topology_t topology, size_t len)
void * hwloc_alloc_membind_nodeset (hwloc_topology_t topology, size_t len,
hwloc_const_nodeset_t nodeset, hwloc_membind_policy_t policy, int flags)
void * hwloc_alloc_membind (hwloc_topology_t topology, size_t len, hwloc_const_cpuset_t
cpuset, hwloc_membind_policy_t policy, int flags)
static inline void * hwloc_alloc_membind_policy_nodeset (hwloc_topology_t topology, size_t
len, hwloc_const_nodeset_t nodeset, hwloc_membind_policy_t policy, int flags)
static inline void * hwloc_alloc_membind_policy (hwloc_topology_t topology, size_t len,
hwloc_const_cpuset_t set, hwloc_membind_policy_t policy, int flags)
int hwloc_free (hwloc_topology_t topology, void *addr, size_t len)
Detailed Description
Memory binding can be done three ways:
• explicit memory allocation thanks to hwloc_alloc_membind and friends: the binding will
have effect on the memory allocated by these functions.
• implicit memory binding through binding policy: hwloc_set_membind and friends only
define the current policy of the process, which will be applied to the subsequent calls
to malloc() and friends.
• migration of existing memory ranges, thanks to hwloc_set_area_membind() and friends,
which move already-allocated data.
Note:
Not all operating systems support all three ways Using a binding flag or policy that
is not supported by the underlying OS will cause hwloc's binding functions to fail and
return -1. errno will be set to ENOSYS when the system does support the specified
action or policy (e.g., some systems only allow binding memory on a per-thread basis,
whereas other systems only allow binding memory for all threads in a process). errno
will be set to EXDEV when the requested cpuset can not be enforced (e.g., some systems
only allow binding memory to a single NUMA node).
The most portable form that should be preferred over the others whenever possible is as
follows:
hwloc_alloc_membind_policy(topology, size, set,
HWLOC_MEMBIND_DEFAULT, 0);
This will allocate some memory hopefully bound to the specified set. To do so, hwloc will
possibly have to change the current memory binding policy in order to actually get the
memory bound, if the OS does not provide any other way to simply allocate bound memory
without changing the policy for all allocations. That is the difference with
hwloc_alloc_membind(), which will never change the current memory binding policy. Note
that since HWLOC_MEMBIND_STRICT was not specified, failures to bind will not be reported
-- generally, only memory allocation failures will be reported (e.g., even a plain
malloc() would have failed with ENOMEM).
Each hwloc memory binding function is available in two forms: one that takes a CPU set
argument and another that takes a NUMA memory node set argument (see Object Sets
(hwloc_cpuset_t and hwloc_nodeset_t) and The bitmap API for a discussion of CPU sets and
NUMA memory node sets). The names of the latter form end with _nodeset. It is also
possible to convert between CPU set and node set using hwloc_cpuset_to_nodeset() or
hwloc_cpuset_from_nodeset().
Note:
On some operating systems, memory binding affects the CPU binding; see
HWLOC_MEMBIND_NOCPUBIND
Enumeration Type Documentation
enum hwloc_membind_flags_t
Memory binding flags. These flags can be used to refine the binding policy. All flags can
be logically OR'ed together with the exception of HWLOC_MEMBIND_PROCESS and
HWLOC_MEMBIND_THREAD; these two flags are mutually exclusive.
Note:
Not all systems support all kinds of binding. See the 'Detailed Description' section
of Memory binding for a description of errors that can occur.
Enumerator
HWLOC_MEMBIND_PROCESS
Set policy for all threads of the specified (possibly multithreaded) process. This
flag is mutually exclusive with HWLOC_MEMBIND_THREAD.
HWLOC_MEMBIND_THREAD
Set policy for a specific thread of the current process. This flag is mutually
exclusive with HWLOC_MEMBIND_PROCESS.
HWLOC_MEMBIND_STRICT
Request strict binding from the OS. The function will fail if the binding can not
be guaranteed / completely enforced.
This flag has slightly different meanings depending on which function it is used with.
HWLOC_MEMBIND_MIGRATE
Migrate existing allocated memory. If the memory cannot be migrated and the
HWLOC_MEMBIND_STRICT flag is passed, an error will be returned.
HWLOC_MEMBIND_NOCPUBIND
Avoid any effect on CPU binding. On some operating systems, some underlying memory
binding functions also bind the application to the corresponding CPU(s). Using this
flag will cause hwloc to avoid using OS functions that could potentially affect CPU
bindings. Note, however, that using NOCPUBIND may reduce hwloc's overall memory
binding support. Specifically: some of hwloc's memory binding functions may fail
with errno set to ENOSYS when used with NOCPUBIND.
enum hwloc_membind_policy_t
Memory binding policy. These constants can be used to choose the binding policy. Only one
policy can be used at a time (i.e., the values cannot be OR'ed together).
Note:
Not all systems support all kinds of binding. See the 'Detailed Description' section
of Memory binding for a description of errors that can occur.
Enumerator
HWLOC_MEMBIND_DEFAULT
Reset the memory allocation policy to the system default.
HWLOC_MEMBIND_FIRSTTOUCH
Allocate memory but do not immediately bind it to a specific locality. Instead,
each page in the allocation is bound only when it is first touched. Pages are
individually bound to the local NUMA node of the first thread that touches it. If
there is not enough memory on the node, allocation may be done in the specified
cpuset before allocating on other nodes.
HWLOC_MEMBIND_BIND
Allocate memory on the specified nodes.
HWLOC_MEMBIND_INTERLEAVE
Allocate memory on the given nodes in an interleaved / round-robin manner. The
precise layout of the memory across multiple NUMA nodes is OS/system specific.
Interleaving can be useful when threads distributed across the specified NUMA nodes
will all be accessing the whole memory range concurrently, since the interleave
will then balance the memory references.
HWLOC_MEMBIND_REPLICATE
Replicate memory on the given nodes; reads from this memory will attempt to be
serviced from the NUMA node local to the reading thread. Replicating can be useful
when multiple threads from the specified NUMA nodes will be sharing the same read-
only data. This policy can only be used with existing memory allocations (i.e., the
hwloc_set_*membind*() functions); it cannot be used with functions that allocate
new memory (i.e., the hwloc_alloc*() functions).
HWLOC_MEMBIND_NEXTTOUCH
For each page bound with this policy, by next time it is touched (and next time
only), it is moved from its current location to the local NUMA node of the thread
where the memory reference occurred (if it needs to be moved at all).
HWLOC_MEMBIND_MIXED
Returned by hwloc_get_membind*() functions when multiple threads or parts of a
memory area have differing memory binding policies.
Function Documentation
void* hwloc_alloc (hwloc_topology_ttopology, size_tlen)
Allocate some memory. This is equivalent to malloc(), except that it tries to allocate
page-aligned memory from the OS.
Note:
The allocated memory should be freed with hwloc_free().
void* hwloc_alloc_membind (hwloc_topology_ttopology, size_tlen, hwloc_const_cpuset_tcpuset,
hwloc_membind_policy_tpolicy, intflags)
Allocate some memory on memory nodes near the given physical cpuset cpuset.
Returns:
NULL with errno set to ENOSYS if the action is not supported and HWLOC_MEMBIND_STRICT
is given
NULL with errno set to EXDEV if the binding cannot be enforced and
HWLOC_MEMBIND_STRICT is given
Note:
The allocated memory should be freed with hwloc_free().
void* hwloc_alloc_membind_nodeset (hwloc_topology_ttopology, size_tlen,
hwloc_const_nodeset_tnodeset, hwloc_membind_policy_tpolicy, intflags)
Allocate some memory on the given physical nodeset nodeset.
Returns:
NULL with errno set to ENOSYS if the action is not supported and HWLOC_MEMBIND_STRICT
is given
NULL with errno set to EXDEV if the binding cannot be enforced and
HWLOC_MEMBIND_STRICT is given
Note:
The allocated memory should be freed with hwloc_free().
static inline void* hwloc_alloc_membind_policy (hwloc_topology_ttopology, size_tlen,
hwloc_const_cpuset_tset, hwloc_membind_policy_tpolicy, intflags) [static]
Allocate some memory on the memory nodes near given cpuset cpuset. This is similar to
hwloc_alloc_membind_policy_nodeset, but for a given cpuset.
static inline void* hwloc_alloc_membind_policy_nodeset (hwloc_topology_ttopology, size_tlen,
hwloc_const_nodeset_tnodeset, hwloc_membind_policy_tpolicy, intflags) [static]
Allocate some memory on the given nodeset nodeset. This is similar to hwloc_alloc_membind
except that it is allowed to change the current memory binding policy, thus providing more
binding support, at the expense of changing the current state.
int hwloc_free (hwloc_topology_ttopology, void *addr, size_tlen)
Free memory that was previously allocated by hwloc_alloc() or hwloc_alloc_membind().
int hwloc_get_area_membind (hwloc_topology_ttopology, const void *addr, size_tlen,
hwloc_cpuset_tcpuset, hwloc_membind_policy_t *policy, intflags)
Query the CPUs near the physical NUMA node(s) and binding policy of the memory identified
by (addr, len ). This function has two output parameters: cpuset and policy. The values
returned in these parameters depend on both the flags passed in and the memory binding
policies and nodesets of the pages in the address range.
If HWLOC_MEMBIND_STRICT is specified, the target pages are first checked to see if they
all have the same memory binding policy and nodeset. If they do not, -1 is returned and
errno is set to EXDEV. If they are identical across all pages, the policy is returned in
policy. cpuset is set to the union of CPUs near the NUMA node(s) in the nodeset.
If HWLOC_MEMBIND_STRICT is not specified, the union of all NUMA node(s) containing pages
in the address range is calculated. cpuset is then set to the CPUs near the NUMA node(s)
in this union. If all pages in the target have the same policy, it is returned in policy.
Otherwise, policy is set to HWLOC_MEMBIND_MIXED.
If any other flags are specified, -1 is returned and errno is set to EINVAL.
int hwloc_get_area_membind_nodeset (hwloc_topology_ttopology, const void *addr, size_tlen,
hwloc_nodeset_tnodeset, hwloc_membind_policy_t *policy, intflags)
Query the physical NUMA node(s) and binding policy of the memory identified by (addr, len
). This function has two output parameters: nodeset and policy. The values returned in
these parameters depend on both the flags passed in and the memory binding policies and
nodesets of the pages in the address range.
If HWLOC_MEMBIND_STRICT is specified, the target pages are first checked to see if they
all have the same memory binding policy and nodeset. If they do not, -1 is returned and
errno is set to EXDEV. If they are identical across all pages, the nodeset and policy are
returned in nodeset and policy, respectively.
If HWLOC_MEMBIND_STRICT is not specified, nodeset is set to the union of all NUMA node(s)
containing pages in the address range. If all pages in the target have the same policy, it
is returned in policy. Otherwise, policy is set to HWLOC_MEMBIND_MIXED.
If any other flags are specified, -1 is returned and errno is set to EINVAL.
int hwloc_get_membind (hwloc_topology_ttopology, hwloc_cpuset_tcpuset, hwloc_membind_policy_t
*policy, intflags)
Query the default memory binding policy and physical locality of the current process or
thread (the locality is returned in cpuset as CPUs near the locality's actual NUMA
node(s)). This function has two output parameters: cpuset and policy. The values returned
in these parameters depend on both the flags passed in and the current memory binding
policies and nodesets in the queried target.
Passing the HWLOC_MEMBIND_PROCESS flag specifies that the query target is the current
policies and nodesets for all the threads in the current process. Passing
HWLOC_MEMBIND_THREAD specifies that the query target is the current policy and nodeset for
only the thread invoking this function.
If neither of these flags are passed (which is the most portable method), the process is
assumed to be single threaded. This allows hwloc to use either process-based OS functions
or thread-based OS functions, depending on which are available.
HWLOC_MEMBIND_STRICT is only meaningful when HWLOC_MEMBIND_PROCESS is also specified. In
this case, hwloc will check the default memory policies and nodesets for all threads in
the process. If they are not identical, -1 is returned and errno is set to EXDEV. If they
are identical, the policy is returned in policy. cpuset is set to the union of CPUs near
the NUMA node(s) in the nodeset.
Otherwise, if HWLOC_MEMBIND_PROCESS is specified (and HWLOC_MEMBIND_STRICT is not
specified), the default nodeset from each thread is logically OR'ed together. cpuset is
set to the union of CPUs near the NUMA node(s) in the resulting nodeset. If all threads'
default policies are the same, policy is set to that policy. If they are different, policy
is set to HWLOC_MEMBIND_MIXED.
In the HWLOC_MEMBIND_THREAD case (or when neither HWLOC_MEMBIND_PROCESS or
HWLOC_MEMBIND_THREAD is specified), there is only one nodeset and policy. The policy is
returned in policy; cpuset is set to the union of CPUs near the NUMA node(s) in the
nodeset.
If any other flags are specified, -1 is returned and errno is set to EINVAL.
int hwloc_get_membind_nodeset (hwloc_topology_ttopology, hwloc_nodeset_tnodeset,
hwloc_membind_policy_t *policy, intflags)
Query the default memory binding policy and physical locality of the current process or
thread. This function has two output parameters: nodeset and policy. The values returned
in these parameters depend on both the flags passed in and the current memory binding
policies and nodesets in the queried target.
Passing the HWLOC_MEMBIND_PROCESS flag specifies that the query target is the current
policies and nodesets for all the threads in the current process. Passing
HWLOC_MEMBIND_THREAD specifies that the query target is the current policy and nodeset for
only the thread invoking this function.
If neither of these flags are passed (which is the most portable method), the process is
assumed to be single threaded. This allows hwloc to use either process-based OS functions
or thread-based OS functions, depending on which are available.
HWLOC_MEMBIND_STRICT is only meaningful when HWLOC_MEMBIND_PROCESS is also specified. In
this case, hwloc will check the default memory policies and nodesets for all threads in
the process. If they are not identical, -1 is returned and errno is set to EXDEV. If they
are identical, the values are returned in nodeset and policy.
Otherwise, if HWLOC_MEMBIND_PROCESS is specified (and HWLOC_MEMBIND_STRICT is not
specified), nodeset is set to the logical OR of all threads' default nodeset. If all
threads' default policies are the same, policy is set to that policy. If they are
different, policy is set to HWLOC_MEMBIND_MIXED.
In the HWLOC_MEMBIND_THREAD case (or when neither HWLOC_MEMBIND_PROCESS or
HWLOC_MEMBIND_THREAD is specified), there is only one nodeset and policy; they are
returned in nodeset and policy, respectively.
If any other flags are specified, -1 is returned and errno is set to EINVAL.
int hwloc_get_proc_membind (hwloc_topology_ttopology, hwloc_pid_tpid, hwloc_cpuset_tcpuset,
hwloc_membind_policy_t *policy, intflags)
Query the default memory binding policy and physical locality of the specified process
(the locality is returned in cpuset as CPUs near the locality's actual NUMA node(s)). This
function has two output parameters: cpuset and policy. The values returned in these
parameters depend on both the flags passed in and the current memory binding policies and
nodesets in the queried target.
Passing the HWLOC_MEMBIND_PROCESS flag specifies that the query target is the current
policies and nodesets for all the threads in the specified process. If
HWLOC_MEMBIND_PROCESS is not specified (which is the most portable method), the process is
assumed to be single threaded. This allows hwloc to use either process-based OS functions
or thread-based OS functions, depending on which are available.
Note that it does not make sense to pass HWLOC_MEMBIND_THREAD to this function.
If HWLOC_MEMBIND_STRICT is specified, hwloc will check the default memory policies and
nodesets for all threads in the specified process. If they are not identical, -1 is
returned and errno is set to EXDEV. If they are identical, the policy is returned in
policy. cpuset is set to the union of CPUs near the NUMA node(s) in the nodeset.
Otherwise, the default nodeset from each thread is logically OR'ed together. cpuset is set
to the union of CPUs near the NUMA node(s) in the resulting nodeset. If all threads'
default policies are the same, policy is set to that policy. If they are different, policy
is set to HWLOC_MEMBIND_MIXED.
If any other flags are specified, -1 is returned and errno is set to EINVAL.
Note:
hwloc_pid_t is pid_t on Unix platforms, and HANDLE on native Windows platforms.
int hwloc_get_proc_membind_nodeset (hwloc_topology_ttopology, hwloc_pid_tpid,
hwloc_nodeset_tnodeset, hwloc_membind_policy_t *policy, intflags)
Query the default memory binding policy and physical locality of the specified process.
This function has two output parameters: nodeset and policy. The values returned in these
parameters depend on both the flags passed in and the current memory binding policies and
nodesets in the queried target.
Passing the HWLOC_MEMBIND_PROCESS flag specifies that the query target is the current
policies and nodesets for all the threads in the specified process. If
HWLOC_MEMBIND_PROCESS is not specified (which is the most portable method), the process is
assumed to be single threaded. This allows hwloc to use either process-based OS functions
or thread-based OS functions, depending on which are available.
Note that it does not make sense to pass HWLOC_MEMBIND_THREAD to this function.
If HWLOC_MEMBIND_STRICT is specified, hwloc will check the default memory policies and
nodesets for all threads in the specified process. If they are not identical, -1 is
returned and errno is set to EXDEV. If they are identical, the values are returned in
nodeset and policy.
Otherwise, nodeset is set to the logical OR of all threads' default nodeset. If all
threads' default policies are the same, policy is set to that policy. If they are
different, policy is set to HWLOC_MEMBIND_MIXED.
If any other flags are specified, -1 is returned and errno is set to EINVAL.
Note:
hwloc_pid_t is pid_t on Unix platforms, and HANDLE on native Windows platforms.
int hwloc_set_area_membind (hwloc_topology_ttopology, const void *addr, size_tlen,
hwloc_const_cpuset_tcpuset, hwloc_membind_policy_tpolicy, intflags)
Bind the already-allocated memory identified by (addr, len) to the NUMA node(s) near
physical cpuset.
Returns:
-1 with errno set to ENOSYS if the action is not supported
-1 with errno set to EXDEV if the binding cannot be enforced
int hwloc_set_area_membind_nodeset (hwloc_topology_ttopology, const void *addr, size_tlen,
hwloc_const_nodeset_tnodeset, hwloc_membind_policy_tpolicy, intflags)
Bind the already-allocated memory identified by (addr, len) to the NUMA node(s) in
physical nodeset.
Returns:
-1 with errno set to ENOSYS if the action is not supported
-1 with errno set to EXDEV if the binding cannot be enforced
int hwloc_set_membind (hwloc_topology_ttopology, hwloc_const_cpuset_tcpuset,
hwloc_membind_policy_tpolicy, intflags)
Set the default memory binding policy of the current process or thread to prefer the NUMA
node(s) near the specified physical cpuset. If neither HWLOC_MEMBIND_PROCESS nor
HWLOC_MEMBIND_THREAD is specified, the current process is assumed to be single-threaded.
This is the most portable form as it permits hwloc to use either process-based OS
functions or thread-based OS functions, depending on which are available.
Returns:
-1 with errno set to ENOSYS if the action is not supported
-1 with errno set to EXDEV if the binding cannot be enforced
int hwloc_set_membind_nodeset (hwloc_topology_ttopology, hwloc_const_nodeset_tnodeset,
hwloc_membind_policy_tpolicy, intflags)
Set the default memory binding policy of the current process or thread to prefer the NUMA
node(s) specified by physical nodeset. If neither HWLOC_MEMBIND_PROCESS nor
HWLOC_MEMBIND_THREAD is specified, the current process is assumed to be single-threaded.
This is the most portable form as it permits hwloc to use either process-based OS
functions or thread-based OS functions, depending on which are available.
Returns:
-1 with errno set to ENOSYS if the action is not supported
-1 with errno set to EXDEV if the binding cannot be enforced
int hwloc_set_proc_membind (hwloc_topology_ttopology, hwloc_pid_tpid,
hwloc_const_cpuset_tcpuset, hwloc_membind_policy_tpolicy, intflags)
Set the default memory binding policy of the specified process to prefer the NUMA node(s)
near the specified physical cpuset.
Returns:
-1 with errno set to ENOSYS if the action is not supported
-1 with errno set to EXDEV if the binding cannot be enforced
Note:
hwloc_pid_t is pid_t on Unix platforms, and HANDLE on native Windows platforms.
int hwloc_set_proc_membind_nodeset (hwloc_topology_ttopology, hwloc_pid_tpid,
hwloc_const_nodeset_tnodeset, hwloc_membind_policy_tpolicy, intflags)
Set the default memory binding policy of the specified process to prefer the NUMA node(s)
specified by physical nodeset.
Returns:
-1 with errno set to ENOSYS if the action is not supported
-1 with errno set to EXDEV if the binding cannot be enforced
Note:
hwloc_pid_t is pid_t on Unix platforms, and HANDLE on native Windows platforms.
Author
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