pthread_attr_setaffinity_np, pthread_attr_getaffinity_np - set/get CPU affinity
attribute in thread attributes object
POSIX threads library (
libpthread,
-lpthread)
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <pthread.h>
int pthread_attr_setaffinity_np(pthread_attr_t *attr,
size_t cpusetsize, const cpu_set_t *cpuset);
int pthread_attr_getaffinity_np(const pthread_attr_t *attr,
size_t cpusetsize, cpu_set_t *cpuset);
The
pthread_attr_setaffinity_np() function sets the CPU affinity mask
attribute of the thread attributes object referred to by
attr to the
value specified in
cpuset. This attribute determines the CPU affinity
mask of a thread created using the thread attributes object
attr.
The
pthread_attr_getaffinity_np() function returns the CPU affinity mask
attribute of the thread attributes object referred to by
attr in the
buffer pointed to by
cpuset.
The argument
cpusetsize is the length (in bytes) of the buffer pointed to
by
cpuset. Typically, this argument would be specified as
sizeof(cpu_set_t).
For more details on CPU affinity masks, see
sched_setaffinity(2). For a
description of a set of macros that can be used to manipulate and inspect CPU
sets, see
CPU_SET(3).
On success, these functions return 0; on error, they return a nonzero error
number.
- EINVAL
- (pthread_attr_setaffinity_np()) cpuset
specified a CPU that was outside the set supported by the kernel. (The
kernel configuration option CONFIG_NR_CPUS defines the range of the
set supported by the kernel data type used to represent CPU sets.)
- EINVAL
- (pthread_attr_getaffinity_np()) A CPU in the
affinity mask of the thread attributes object referred to by attr
lies outside the range specified by cpusetsize (i.e.,
cpuset/cpusetsize is too small).
- ENOMEM
- (pthread_attr_setaffinity_np()) Could not allocate
memory.
These functions are provided since glibc 2.3.4.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
pthread_attr_setaffinity_np (), pthread_attr_getaffinity_np () |
Thread safety |
MT-Safe |
These functions are nonstandard GNU extensions; hence the suffix "_np"
(nonportable) in the names.
In glibc 2.3.3 only, versions of these functions were provided that did not have
a
cpusetsize argument. Instead the CPU set size given to the underlying
system calls was always
sizeof(cpu_set_t).
sched_setaffinity(2),
pthread_attr_init(3),
pthread_setaffinity_np(3),
cpuset(7),
pthreads(7)