xref: /freebsd/lib/libsys/cpuset_getdomain.2 (revision 783d3ff6d7fae619db8a7990b8a6387de0c677b5)
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25.Dd June 18, 2020
26.Dt CPUSET_GETDOMAIN 2
27.Os
28.Sh NAME
29.Nm cpuset_getdomain ,
30.Nm cpuset_setdomain
31.Nd manage memory domain policy
32.Sh LIBRARY
33.Lb libc
34.Sh SYNOPSIS
35.In sys/param.h
36.In sys/domainset.h
37.Ft int
38.Fn cpuset_getdomain "cpulevel_t level" "cpuwhich_t which" "id_t id" "size_t setsize" "domainset_t *mask" "int *policy"
39.Ft int
40.Fn cpuset_setdomain "cpulevel_t level" "cpuwhich_t which" "id_t id" "size_t setsize" "const domainset_t *mask" "int policy"
41.Sh DESCRIPTION
42.Fn cpuset_getdomain
43and
44.Fn cpuset_setdomain
45allow the manipulation of sets of memory domains and allocation policy available
46to processes, threads, jails and other resources.
47These functions may manipulate sets of memory domains that contain many processes
48or per-object anonymous masks that affect only a single object.
49.Pp
50The valid values for the
51.Fa level
52and
53.Fa which
54arguments are documented in
55.Xr cpuset 2 .
56These arguments specify which object and which set of the object we are
57referring to.
58Not all possible combinations are valid.
59For example, only processes may belong to a numbered set accessed by a
60.Fa level
61argument of
62.Dv CPU_LEVEL_CPUSET .
63All resources, however, have a mask which may be manipulated with
64.Dv CPU_LEVEL_WHICH .
65.Pp
66Masks of type
67.Ft domainset_t
68are composed using the
69.Dv DOMAINSET
70macros.
71The kernel tolerates large sets as long as all domains specified
72in the set exist.
73Sets smaller than the kernel uses generate an error on calls to
74.Fn cpuset_getdomain
75even if the result set would fit within the user supplied set.
76Calls to
77.Fn cpuset_setdomain
78tolerate small sets with no restrictions.
79.Pp
80The supplied mask should have a size of
81.Fa setsize
82bytes.
83This size is usually provided by calling
84.Li sizeof(mask)
85which is ultimately determined by the value of
86.Dv DOMAINSET_SETSIZE
87as defined in
88.In sys/domainset.h .
89.Pp
90.Fn cpuset_getdomain
91retrieves the
92mask and policy from the object specified by
93.Fa level ,
94.Fa which
95and
96.Fa id
97and stores it in the space provided by
98.Fa mask
99and
100.Fa policy .
101.Pp
102.Fn cpuset_setdomain
103attempts to set the mask and policy for the object specified by
104.Fa level ,
105.Fa which
106and
107.Fa id
108to the values in
109.Fa mask
110and
111.Fa policy .
112.Sh ALLOCATION POLICIES
113Valid policy values are as follows:
114.Bl -tag -width "foo"
115.It Dv DOMAINSET_POLICY_ROUNDROBIN
116Memory is allocated on a round-robin basis by cycling through each domain in
117.Fa mask .
118.It Dv DOMAINSET_POLICY_FIRSTTOUCH
119Memory is allocated on the domain local to the CPU the requesting thread is
120running on.
121Failure to allocate from this domain will fallback to round-robin.
122.It Dv DOMAINSET_POLICY_PREFER
123Memory is allocated preferentially from the single domain specified in the mask.
124If memory is unavailable the domains listed in the parent cpuset will be
125visited in a round-robin order.
126.El
127.Sh RETURN VALUES
128.Rv -std
129.Sh ERRORS
130The following error codes may be set in
131.Va errno :
132.Bl -tag -width Er
133.\" When changing this list, consider updating share/man/man3/pthread_create.3,
134.\" since that function can return any of these errors.
135.It Bq Er EINVAL
136The
137.Fa level
138or
139.Fa which
140argument was not a valid value.
141.It Bq Er EINVAL
142The
143.Fa mask or
144.Fa policy
145argument specified when calling
146.Fn cpuset_setdomain
147was not a valid value.
148.It Bq Er EDEADLK
149The
150.Fn cpuset_setdomain
151call would leave a thread without a valid CPU to run on because the set
152does not overlap with the thread's anonymous mask.
153.It Bq Er EFAULT
154The mask pointer passed was invalid.
155.It Bq Er ESRCH
156The object specified by the
157.Fa id
158and
159.Fa which
160arguments could not be found.
161.It Bq Er ERANGE
162The
163.Fa domainsetsize
164was either preposterously large or smaller than the kernel set size.
165.It Bq Er EPERM
166The calling process did not have the credentials required to complete the
167operation.
168.It Bq Er ECAPMODE
169The calling process attempted to act on a process other than itself, while
170in capability mode.
171See
172.Xr capsicum 4 .
173.El
174.Sh SEE ALSO
175.Xr cpuset 1 ,
176.Xr cpuset 2 ,
177.Xr cpuset_getaffinity 2 ,
178.Xr cpuset_getid 2 ,
179.Xr cpuset_setaffinity 2 ,
180.Xr cpuset_setid 2 ,
181.Xr capsicum 4 ,
182.Xr cpuset 9
183.Sh HISTORY
184The
185.Nm
186family of system calls first appeared in
187.Fx 12.0 .
188.Sh AUTHORS
189.An Jeffrey Roberson Aq Mt jeff@FreeBSD.org
190