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freebsd/lib/libc/sys/cpuset_getaffinity.2

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.\" Copyright (c) 2008 Christian Brueffer
.\" Copyright (c) 2008 Jeffrey Roberson
.\" All rights reserved.
.\"
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.Dd September 10, 2010
.Dt CPUSET 2
.Os
.Sh NAME
.Nm cpuset_getaffinity ,
.Nm cpuset_setaffinity
.Nd manage CPU affinity
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/param.h
.In sys/cpuset.h
.Ft int
.Fn cpuset_getaffinity "cpulevel_t level" "cpuwhich_t which" "id_t id" "size_t setsize" "cpuset_t *mask"
.Ft int
.Fn cpuset_setaffinity "cpulevel_t level" "cpuwhich_t which" "id_t id" "size_t setsize" "const cpuset_t *mask"
.Sh DESCRIPTION
.Fn cpuset_getaffinity
and
.Fn cpuset_setaffinity
allow the manipulation of sets of CPUs available to processes, threads,
MFp4: Bring in updated jail support from bz_jail branch. This enhances the current jail implementation to permit multiple addresses per jail. In addtion to IPv4, IPv6 is supported as well. Due to updated checks it is even possible to have jails without an IP address at all, which basically gives one a chroot with restricted process view, no networking,.. SCTP support was updated and supports IPv6 in jails as well. Cpuset support permits jails to be bound to specific processor sets after creation. Jails can have an unrestricted (no duplicate protection, etc.) name in addition to the hostname. The jail name cannot be changed from within a jail and is considered to be used for management purposes or as audit-token in the future. DDB 'show jails' command was added to aid debugging. Proper compat support permits 32bit jail binaries to be used on 64bit systems to manage jails. Also backward compatibility was preserved where possible: for jail v1 syscalls, as well as with user space management utilities. Both jail as well as prison version were updated for the new features. A gap was intentionally left as the intermediate versions had been used by various patches floating around the last years. Bump __FreeBSD_version for the afore mentioned and in kernel changes. Special thanks to: - Pawel Jakub Dawidek (pjd) for his multi-IPv4 patches and Olivier Houchard (cognet) for initial single-IPv6 patches. - Jeff Roberson (jeff) and Randall Stewart (rrs) for their help, ideas and review on cpuset and SCTP support. - Robert Watson (rwatson) for lots and lots of help, discussions, suggestions and review of most of the patch at various stages. - John Baldwin (jhb) for his help. - Simon L. Nielsen (simon) as early adopter testing changes on cluster machines as well as all the testers and people who provided feedback the last months on freebsd-jail and other channels. - My employer, CK Software GmbH, for the support so I could work on this. Reviewed by: (see above) MFC after: 3 months (this is just so that I get the mail) X-MFC Before: 7.2-RELEASE if possible
2008-11-29 14:32:14 +00:00
interrupts, jails and other resources.
These functions may manipulate sets of CPUs that contain many processes
or per-object anonymous masks that effect only a single object.
.Pp
The valid values for the
.Fa level
and
.Fa which
arguments are documented in
.Xr cpuset 2 .
These arguments specify which object and which set of the object we are
referring to.
Not all possible combinations are valid.
For example, only processes may belong to a numbered set accessed by a
.Fa level
argument of
.Dv CPU_LEVEL_CPUSET .
All resources, however, have a mask which may be manipulated with
.Dv CPU_LEVEL_WHICH .
.Pp
Masks of type
.Ft cpuset_t
are composed using the
.Xr CPU_SET 2
macros.
The kernel tolerates large sets as long as all CPUs specified
in the set exist.
Sets smaller than the kernel uses generate an error on calls to
.Fn cpuset_getaffinity
even if the result set would fit within the user supplied set.
Calls to
.Fn cpuset_setaffinity
tolerate small sets with no restrictions.
.Pp
The supplied mask should have a size of
.Fa setsize
bytes.
This size is usually provided by calling
.Li sizeof(mask)
which is ultimately determined by the value of
.Dv CPU_SETSIZE
as defined in
.In sys/cpuset.h .
.Pp
.Fn cpuset_getaffinity
retrieves the
mask from the object specified by
.Fa level ,
.Fa which
and
.Fa id
and stores it in the space provided by
.Fa mask .
.Pp
.Fn cpuset_setaffinity
attempts to set the mask for the object specified by
.Fa level ,
.Fa which
and
.Fa id
to the value in
.Fa mask .
.Pp
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
The following error codes may be set in
.Va errno :
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa level
or
.Fa which
argument was not a valid value.
.It Bq Er EINVAL
The
.Fa mask
argument specified when calling
.Fn cpuset_setaffinity
was not a valid value.
.It Bq Er EDEADLK
The
.Fn cpuset_setaffinity
call would leave a thread without a valid CPU to run on because the set
does not overlap with the thread's anonymous mask.
.It Bq Er EFAULT
The mask pointer passed was invalid.
.It Bq Er ESRCH
The object specified by the
.Fa id
and
.Fa which
arguments could not be found.
.It Bq Er ERANGE
The
.Fa cpusetsize
was either preposterously large or smaller than the kernel set size.
.It Bq Er EPERM
The calling process did not have the credentials required to complete the
operation.
.El
.Sh SEE ALSO
.Xr cpuset 1 ,
.Xr cpuset 2 ,
.Xr cpuset_getid 2 ,
.Xr cpuset_setid 2 ,
.Xr CPU_SET 3 ,
.Xr pthread_affinity_np 3 ,
.Xr pthread_attr_affinity_np 3
.Sh HISTORY
The
.Nm
family of system calls first appeared in
.Fx 7.1 .
.Sh AUTHOR
.An Jeffrey Roberson Aq jeff@FreeBSD.org