1.\" Copyright (c) 2018 Jeffrey Roberson <jeff@FreeBSD.org> 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' 14.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 15.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE 17.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 18.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 19.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 20.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 21.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 22.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 23.\" POSSIBILITY OF SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd October 30, 2018 28.Dt DOMAINSET 9 29.Os 30.Sh NAME 31.Nm domainset(9) 32.Nd domainset functions and operation 33.Sh SYNOPSIS 34.In sys/_domainset.h 35.In sys/domainset.h 36.\" 37.Bd -literal -offset indent 38struct domainset { 39 domainset_t ds_mask; 40 uint16_t ds_policy; 41 domainid_t ds_prefer; 42 ... 43}; 44.Ed 45.Pp 46.Ft struct domainset * 47.Fn DOMAINSET_FIXED domain 48.Ft struct domainset * 49.Fn DOMAINSET_RR 50.Ft struct domainset * 51.Fn DOMAINSET_PREF domain 52.Ft struct domainset * 53.Fn domainset_create "const struct domainset *key" 54.Ft int 55.Fn sysctl_handle_domainset "SYSCTL_HANDLER_ARGS" 56.Sh DESCRIPTION 57The 58.Nm 59API provides memory domain allocation policy for NUMA machines. 60Each 61.Vt domainset 62contains a bitmask of allowed domains, an integer policy, and an optional 63preferred domain. 64Together, these specify a search order for memory allocations as well as 65the ability to restrict threads and objects to a subset of available 66memory domains for system partitioning and resource management. 67.Pp 68Every thread in the system and optionally every 69.Vt vm_object_t , 70which is used to represent files and other memory sources, has 71a reference to a 72.Vt struct domainset . 73The domainset associated with the object is consulted first and the system 74falls back to the thread policy if none exists. 75.Pp 76The allocation policy has the following possible values: 77.Bl -tag -width "foo" 78.It Dv DOMAINSET_POLICY_ROUNDROBIN 79Memory is allocated from each domain in the mask in a round-robin fashion. 80This distributes bandwidth evenly among available domains. 81This policy can specify a single domain for a fixed allocation. 82.It Dv DOMAINSET_POLICY_FIRSTTOUCH 83Memory is allocated from the node that it is first accessed on. 84Allocation falls back to round-robin if the current domain is not in the 85allowed set or is out of memory. 86This policy optimizes for locality but may give pessimal results if the 87memory is accessed from many CPUs that are not in the local domain. 88.It Dv DOMAINSET_POLICY_PREFER 89Memory is allocated from the node in the 90.Vt prefer 91member. 92The preferred node must be set in the allowed mask. 93If the preferred node is out of memory the allocation falls back to 94round-robin among allowed sets. 95.It Dv DOMAINSET_POLICY_INTERLEAVE 96Memory is allocated in a striped fashion with multiple pages 97allocated to each domain in the set according to the offset within 98the object. 99The strip width is object dependent and may be as large as a 100super-page (2MB on amd64). 101This gives good distribution among memory domains while keeping system 102efficiency higher and is preferential to round-robin for general use. 103.El 104.Pp 105The 106.Fn DOMAINSET_FIXED , 107.Fn DOMAINSET_RR 108and 109.Fn DOMAINSET_PREF 110macros provide pointers to global pre-defined policies for use when the 111desired policy is known at compile time. 112.Fn DOMAINSET_FIXED 113is a policy which only permits allocations from the specified domain. 114.Fn DOMAINSET_RR 115provides round-robin selection among all domains in the system. 116The 117.Fn DOMAINSET_PREF 118policies attempt allocation from the specified domain, but unlike 119.Fn DOMAINSET_FIXED 120will fall back to other domains to satisfy the request. 121These policies should be used in preference to 122.Fn DOMAINSET_FIXED 123to avoid blocking indefinitely on a 124.Dv M_WAITOK 125request. 126The 127.Fn domainset_create 128function takes a partially filled in domainset as a key and returns a 129valid domainset or NULL. 130It is critical that consumers not use domainsets that have not been 131returned by this function. 132.Vt domainset 133is an immutable type that is shared among all matching keys and must 134not be modified after return. 135.Pp 136The 137.Fn sysctl_handle_domainset 138function is provided as a convenience for modifying or viewing domainsets 139that are not accessible via 140.Xr cpuset 2 . 141It is intended for use with 142.Xr sysctl 9 . 143.Sh SEE ALSO 144.Xr cpuset 1 , 145.Xr cpuset 2 , 146.Xr cpuset_setdomain 2 , 147.Xr bitset 9 148.Sh HISTORY 149.In sys/domainset.h 150first appeared in 151.Fx 12.0 . 152