xref: /freebsd/lib/libsys/cpuset_getdomain.2 (revision 8269e7673cf033aba67dab8264fe719920c70f87)

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.Dd June 18, 2020
.Dt CPUSET_GETDOMAIN 2
.Os
.Sh NAME
.Nm cpuset_getdomain ,
.Nm cpuset_setdomain
.Nd manage memory domain policy
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/param.h
.In sys/domainset.h
.Ft int
.Fn cpuset_getdomain "cpulevel_t level" "cpuwhich_t which" "id_t id" "size_t setsize" "domainset_t *mask" "int *policy"
.Ft int
.Fn cpuset_setdomain "cpulevel_t level" "cpuwhich_t which" "id_t id" "size_t setsize" "const domainset_t *mask" "int policy"
.Sh DESCRIPTION
.Fn cpuset_getdomain
and
.Fn cpuset_setdomain
allow the manipulation of sets of memory domains and allocation policy available
to processes, threads, jails and other resources.
These functions may manipulate sets of memory domains that contain many processes
or per-object anonymous masks that affect 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 domainset_t
are composed using the
.Dv DOMAINSET
macros.
The kernel tolerates large sets as long as all domains specified
in the set exist.
Sets smaller than the kernel uses generate an error on calls to
.Fn cpuset_getdomain
even if the result set would fit within the user supplied set.
Calls to
.Fn cpuset_setdomain
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 DOMAINSET_SETSIZE
as defined in
.In sys/domainset.h .
.Pp
.Fn cpuset_getdomain
retrieves the
mask and policy from the object specified by
.Fa level ,
.Fa which
and
.Fa id
and stores it in the space provided by
.Fa mask
and
.Fa policy .
.Pp
.Fn cpuset_setdomain
attempts to set the mask and policy for the object specified by
.Fa level ,
.Fa which
and
.Fa id
to the values in
.Fa mask
and
.Fa policy .
.Sh ALLOCATION POLICIES
Valid policy values are as follows:
.Bl -tag -width "foo"
.It Dv DOMAINSET_POLICY_ROUNDROBIN
Memory is allocated on a round-robin basis by cycling through each domain in
.Fa mask .
.It Dv DOMAINSET_POLICY_FIRSTTOUCH
Memory is allocated on the domain local to the CPU the requesting thread is
running on.
Failure to allocate from this domain will fallback to round-robin.
.It Dv DOMAINSET_POLICY_PREFER
Memory is allocated preferentially from the single domain specified in the mask.
If memory is unavailable the domains listed in the parent cpuset will be
visited in a round-robin order.
.El
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
The following error codes may be set in
.Va errno :
.Bl -tag -width Er
.\" When changing this list, consider updating share/man/man3/pthread_create.3,
.\" since that function can return any of these errors.
.It Bq Er EINVAL
The
.Fa level
or
.Fa which
argument was not a valid value.
.It Bq Er EINVAL
The
.Fa mask or
.Fa policy
argument specified when calling
.Fn cpuset_setdomain
was not a valid value.
.It Bq Er EDEADLK
The
.Fn cpuset_setdomain
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 domainsetsize
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.
.It Bq Er ECAPMODE
The calling process attempted to act on a process other than itself, while
in capability mode.
See
.Xr capsicum 4 .
.El
.Sh SEE ALSO
.Xr cpuset 1 ,
.Xr cpuset 2 ,
.Xr cpuset_getaffinity 2 ,
.Xr cpuset_getid 2 ,
.Xr cpuset_setaffinity 2 ,
.Xr cpuset_setid 2 ,
.Xr capsicum 4 ,
.Xr cpuset 9
.Sh HISTORY
The
.Nm
family of system calls first appeared in
.Fx 12.0 .
.Sh AUTHORS
.An Jeffrey Roberson Aq Mt jeff@FreeBSD.org