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26 .TH PTHREAD_ATTR_SETAFFINITY_NP 3 2010-09-10 "Linux" "Linux Programmer's Manual"
28 pthread_attr_setaffinity_np, pthread_attr_getaffinity_np \- set/get
29 CPU affinity attribute in thread attributes object
32 .BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
33 .B #include <pthread.h>
35 .BI "int pthread_attr_setaffinity_np(pthread_attr_t *" attr ,
36 .BI " size_t " cpusetsize ", const cpu_set_t *" cpuset );
37 .BI "int pthread_attr_getaffinity_np(pthread_attr_t *" attr ,
38 .BI " size_t " cpusetsize ", cpu_set_t *" cpuset );
40 Compile and link with \fI\-pthread\fP.
44 .BR pthread_attr_setaffinity_np ()
46 sets the CPU affinity mask attribute of the
47 thread attributes object referred to by
49 to the value specified in
51 This attribute determines the CPU affinity mask
52 of a thread created using the thread attributes object
56 .BR pthread_attr_getaffinity_np ()
58 returns the CPU affinity mask attribute of the thread attributes object
61 in the buffer pointed to by
66 is the length (in bytes) of the buffer pointed to by
68 Typically, this argument would be specified as
69 .IR sizeof(cpu_set_t) .
71 For more details on CPU affinity masks, see
72 .BR sched_setaffinity (2).
73 For a description of a set of macros
74 that can be used to manipulate and inspect CPU sets, see
77 On success, these functions return 0;
78 on error, they return a nonzero error number.
82 .RB ( pthread_attr_setaffinity_np ())
84 specified a CPU that was outside the set supported by the kernel.
85 (The kernel configuration option
87 defines the range of the set supported by the kernel data type
89 used to represent CPU sets.)
90 .\" The raw sched_getaffinity() system call returns the size (in bytes)
91 .\" of the cpumask_t type.
94 .RB ( pthread_attr_getaffinity_np ())
95 A CPU in the affinity mask of the thread attributes object referred to by
97 lies outside the range specified by
100 .IR cpuset / cpusetsize
104 .RB ( pthread_attr_setaffinity_np ())
105 Could not allocate memory.
107 These functions are provided by glibc since version 2.3.4.
109 These functions are nonstandard GNU extensions;
110 hence the suffix "_np" (nonportable) in the names.
113 versions of these functions were provided that did not have a
116 Instead the CPU set size given to the underlying system calls was always
117 .IR sizeof(cpu_set_t) .
119 .BR sched_setaffinity (2),
120 .BR pthread_attr_init (3),
121 .BR pthread_setaffinity_np (3),
125 This page is part of release 3.64 of the Linux
128 A description of the project,
129 and information about reporting bugs,
131 \%http://www.kernel.org/doc/man\-pages/.