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Add code examples to cpuset(2), and improve cross referencing.

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MFC after:	1 week
Reviewed by:	jeff, jrtc27, kevans, bcr (manpages)
Differential revision:	https://reviews.freebsd.org/D27803
This commit is contained in:
Robert Watson 2021-04-25 15:22:00 +01:00
parent 5d1d844a77
commit 8e491aaeac
1 changed files with 66 additions and 0 deletions
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66
lib/libc/sys/cpuset.2
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@ -1,5 +1,6 @@
.\" Copyright (c) 2008 Christian Brueffer
.\" Copyright (c) 2008 Jeffrey Roberson
.\" Copyright (c) 2021 Robert N. M. Watson
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
@ -180,9 +181,72 @@ The actual contents of the sets may be retrieved or manipulated using
.Xr cpuset_setaffinity 2 ,
.Xr cpuset_getdomain 2 , and
.Xr cpuset_setdomain 2 .
The
.Xr cpuset 9
macros may be used to manipulate masks of type
.Ft cpuset_t
get and set using those APIs.
See those manual pages for more detail.
.Sh RETURN VALUES
.Rv -std
.Sh EXAMPLES
In this example, a CPU set mask is configured to limit execution to the first
CPU using
.Xr CPU_ZERO 9
and
.Xr CPU_SET 9 ,
members of the
.Xr cpuset 9
programming interface.
Then, the mask is applied to a new anonymous CPU set associated with the
current process using
.Xr cpuset_setaffinity 2 .
This mask will be used by the current process, and inherited by any new
child processes.
.Bd -literal -offset indent
#include <sys/param.h>
#include <sys/cpuset.h>
#include <sysexits.h>
cpuset_t cpuset_mask;
/* Initialize a CPU mask and enable CPU 0. */
CPU_ZERO(&cpuset_mask);
CPU_SET(0, &cpuset_mask);
/* Set affinity for the CPU set for the current process. */
if (cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1,
sizeof(cpuset_mask), &cpuset_mask) < 0)
err(EX_OSERR, "cpuset_setaffinity");
.Ed
.Pp
In the next example, a named CPU set is created containing the current
process, and its affinity similarly configured.
The resulting CPU set ID can then be used for further external management of
the affinity of the set.
.Bd -literal -offset indent
#include <sys/param.h>
#include <sys/cpuset.h>
#include <sysexits.h>
cpusetid_t cpuset_id;
cpuset_t cpuset_mask;
/* Create new cpuset for the current process. */
if (cpuset(&cpuset_id) < 0)
err(EX_OSERR, "cpuset");
/* Initialize a CPU mask and enable CPU 0. */
CPU_ZERO(&cpuset_mask);
CPU_SET(0, &cpuset_mask);
/* Set affinity for the CPU set for the current process. */
if (cpuset_setaffinity(CPU_LEVEL_SET, CPU_WHICH_CPUSET, cpuset_id,
sizeof(cpuset_mask), &cpuset_mask) < 0)
err(EX_OSERR, "cpuset_setaffinity");
.Ed
.Sh ERRORS
The following error codes may be set in
.Va errno :
@ -226,6 +290,8 @@ for allocation.
.Xr cpuset_setdomain 2 ,
.Xr pthread_affinity_np 3 ,
.Xr pthread_attr_affinity_np 3 ,
.Xr CPU_SET 9 ,
.Xr CPU_ZERO 9 ,
.Xr cpuset 9
.Sh HISTORY
The