path: root/lib/libc/sys/numa_getaffinity.2

.\" Copyright (c) 2008 Christian Brueffer
.\" Copyright (c) 2008 Jeffrey Roberson
.\" Copyright (c) 2015 Adrian Chadd
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.Dd May 7, 2015
.Dt NUMA_GETAFFINITY 2
.Os
.Sh NAME
.Nm numa_getaffinity ,
.Nm numa_setaffinity
.Nd manage NUMA affinity
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/param.h
.In sys/numa.h
.Ft int
.Fn numa_getaffinity "cpuwhich_t which" "id_t id" "struct vm_domain_policy_entry *policy"
.Ft int
.Fn numa_setaffinity "cpuwhich_t which" "id_t id" "const struct vm_domain_policy_entry *policy"
.Sh DESCRIPTION
.Fn numa_getaffinity
and
.Fn numa_setaffinity
allow the manipulation of NUMA policies available to processes and threads.
These functions may manipulate NUMA policies that contain many processes
or affect only a single object.
.Pp
Valid values for the
.Fa which
argument are documented in
.Xr cpuset 2 .
These arguments specify which object set are used.
Only
.Dv CPU_WHICH_TID
and
.Dv CPU_WHICH_PID
can be manipulated.
.Pp
The
.Fa policy
entry contains a vm_domain_policy_entry with the following fields:
.Bd -literal
struct vm_domain_policy_entry {
    vm_domain_policy_type_t policy;   /* VM policy */
    int domain;   /* VM domain, if applicable */
}
.Ed
.Fa vm_domain_policy_type_t policy
is one these:
.Bl -tag -width VM_POLICY_NONE
.It Dv VM_POLICY_NONE
Reset the domain back to none.
Any parent object NUMA domain policy will apply.
The only valid value for
.Dv domain
is -1.
.It Dv VM_POLICY_ROUND_ROBIN
Select round-robin policy.
Pages will be allocated round-robin from each VM domain in order.
The only valid value for
.Dv domain
is -1.
.It Dv VM_POLICY_FIXED_DOMAIN
Select fixed-domain only policy.
Pages will be allocated from the given
.Dv domain
which must be set to a valid VM domain.
Pages will not be allocated from another domain if
.Dv domain
is out of free pages.
.It Dv VM_POLICY_FIXED_DOMAIN_ROUND_ROBIN
Select fixed-domain only policy.
Pages will be allocated from
.Dv domain
which must be set to a valid VM domain.
If page allocation fails, pages will be round-robin
allocated from another domain if
.Dv domain
is out of free pages.
.It Dv VM_POLICY_FIRST_TOUCH
Select first-touch policy.
Pages will be allocated from the NUMA domain which the thread
is currently scheduled upon.
Pages will not be allocated from another domain if the current domain
is out of free pages.
The only valid value for
.Dv domain
is -1.
.It Dv VM_POLICY_FIRST_TOUCH_ROUND_ROBIN
Select first-touch policy.
Pages will be allocated from the NUMA domain which the thread
is currently scheduled upon.
Pages will be allocated round-robin from another domain if the
current domain is out of free pages.
The only valid value for
.Dv domain
is -1.
.El
.Pp
Note that the VM might assign some pages from other domains.
For example, if an existing page allocation is covered by a superpage
allocation.
.Pp
.Fn numa_getaffinity
retrieves the
NUMA policy from the object specified by
.Fa which
and
.Fa id
and stores it in the space provided by
.Fa policy .
.Pp
.Fn numa_setaffinity
attempts to set the NUMA policy for the object specified by
.Fa which
and
.Fa id
to the policy in
.Fa policy .
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
.Va errno
can contain these error codes:
.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 policy
argument specified when calling
.Fn numa_setaffinity
did not contain a valid policy.
.It Bq Er EFAULT
The policy 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 domain
in the given policy
was out of the range of possible VM domains available.
.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 numactl 1 ,
.Xr cpuset 2 ,
.Xr cpuset_getaffinity 2 ,
.Xr cpuset_getid 2 ,
.Xr cpuset_setaffinity 2 ,
.Xr cpuset_setid 2 ,
.Xr pthread_affinity_np 3 ,
.Xr pthread_attr_affinity_np 3 ,
.Xr numa 4
.Sh HISTORY
The
.Nm
family of system calls first appeared in
.Fx 11.0 .
.Sh AUTHORS
.An Adrian Chadd Aq Mt adrian@FreeBSD.org