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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