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pthread_setaffinity_np.3: Various improvements after review by Loc Domaigne 

Various fix-ups after Loc's review.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Loc Domaigne <tech@domaigne.com>
This commit is contained in:
Michael Kerrisk 2008-11-14 10:01:23 -05:00
parent 23bb5732b2
commit f5bf1e9b13
1 changed files with 29 additions and 13 deletions
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42
man3/pthread_setaffinity_np.3
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@ -21,7 +21,7 @@
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.TH PTHREAD_SETAFFINITY_NP 3 2008-11-11 "Linux" "Linux Programmer's Manual"
.TH PTHREAD_SETAFFINITY_NP 3 2008-11-14 "Linux" "Linux Programmer's Manual"
.SH NAME
pthread_setaffinity_np, pthread_getaffinity_np \- set/get
CPU affinity of a thread
@ -55,18 +55,21 @@ function returns the CPU affinity mask of the thread
in the buffer pointed to by
.IR cpuset .
For more details on CPU affinity masks, see
.BR sched_setaffinity (2).
For a description of a set of macros
that can be used to manipulate and inspect CPU sets, see
.BR CPU_SET (3).
The argument
.I cpusetsize
is the length (in bytes) of the buffer pointed to by
.IR cpuset .
Typically, this argument would be specified as
.IR sizeof(cpu_set_t) .
For more details on CPU affinity masks, see
.BR sched_setaffinity (2).
For a description of a set of macros
that can be used to manipulate and inspect CPU sets, see
.BR CPU_SET (3).
(It may be some other value, if using the macros described in
.BR CPU_SET (3)
for dynamically allocating a CPU set.)
.SH RETURN VALUE
On success, these functions return 0;
on error, they return a non-zero error number.
@ -79,19 +82,19 @@ A supplied memory address was invalid.
.RB ( pthread_setaffinity_np ())
The affinity bit mask
.I mask
contains no processors that are physically on the system.
contains no processors that are currently physically on the system.
.TP
.BR EINVAL
.RB ( pthread_setaffinity_np ())
.I cpuset
specified a CPU that was outside the range
permitted by the kernel data type
specified a CPU that was outside the set supported by the kernel.
(The kernel configuration option
.BR CONFIG_NR_CPUS
defines the range of the set supported by the kernel data type
.\" cpumask_t
used to represent CPU sets.
used to represent CPU sets.)
.\" The raw sched_getaffinity() system call returns the size (in bytes)
.\" of the cpumask_t type.
This range is determined by the kernel configuration option
.BR CONFIG_NR_CPUS .
.TP
.B EINVAL
.RB ( pthread_getaffinity_np ())
@ -108,6 +111,19 @@ These functions are provided by glibc since version 2.3.4.
These functions are non-standard GNU extensions;
hence the suffix "_np" (non-portable) in the names.
.SH NOTES
After a call to
.BR pthread_setaffinity_np (3),
the set of CPUs on which the thread will actually run is
the intersection of the set specified in the
.I cpuset
argument and the set of CPUs actually present on the system.
The system may further restrict the set of CPUs on which the thread
runs if the "cpuset" mechanism described in
.BR cpuset (7)
is being used.
These restrictions on the actual set of CPUs on which the thread
will run are silently imposed by the kernel.
These functions are implemented on top of the
.BR sched_setaffinity (2)
and