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--- old/usr/src/man/man7/FSS.7
+++ new/usr/src/man/man7/FSS.7
1 -'\" te
2 1 .\" Copyright (c) 2001, Sun Microsystems, Inc. All Rights Reserved
3 -.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License.
4 -.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License.
5 -.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
6 -.TH FSS 7 "May 13, 2017"
7 -.SH NAME
8 -FSS \- Fair share scheduler
9 -.SH DESCRIPTION
10 -.LP
2 +.\" Copyright 2019 Joyent, Inc.
3 +.\"
4 +.\" The contents of this file are subject to the terms of the
5 +.\" Common Development and Distribution License (the "License").
6 +.\" You may not use this file except in compliance with the License.
7 +.\"
8 +.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 +.\" or http://www.opensolaris.org/os/licensing.
10 +.\" See the License for the specific language governing permissions
11 +.\" and limitations under the License.
12 +.\"
13 +.\" When distributing Covered Code, include this CDDL HEADER in each
14 +.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 +.\" If applicable, add the following below this CDDL HEADER, with the
16 +.\" fields enclosed by brackets "[]" replaced with your own identifying
17 +.\" information: Portions Copyright [yyyy] [name of copyright owner]
18 +.\"
19 +.Dd December 17, 2019
20 +.Dt FSS 7
21 +.Os
22 +.Sh NAME
23 +.Nm FSS
24 +.Nd Fair share scheduler
25 +.Sh DESCRIPTION
11 26 The fair share scheduler (FSS) guarantees application performance by explicitly
12 -allocating shares of CPU resources to projects. A share indicates a project's
13 -entitlement to available CPU resources. Because shares are meaningful only in
27 +allocating shares of CPU resources to projects.
28 +A share indicates a project's
29 +entitlement to available CPU resources.
30 +Because shares are meaningful only in
14 31 comparison with other project's shares, the absolute quantity of shares is not
15 -important. Any number that is in proportion with the desired CPU entitlement
32 +important.
33 +Any number that is in proportion with the desired CPU entitlement
16 34 can be used.
17 -.sp
18 -.LP
35 +.Pp
19 36 The goals of the FSS scheduler differ from the traditional time-sharing
20 -scheduling class (TS). In addition to scheduling individual LWPs, the FSS
37 +scheduling class (TS).
38 +In addition to scheduling individual LWPs, the FSS
21 39 scheduler schedules projects against each other, making it impossible for any
22 40 project to acquire more CPU cycles simply by running more processes
23 41 concurrently.
24 -.sp
25 -.LP
42 +.Pp
26 43 A project's entitlement is individually calculated by FSS independently for
27 -each processor set if the project contains processes bound to them. If a
44 +each processor set if the project contains processes bound to them.
45 +If a
28 46 project is running on more than one processor set, it can have different
29 -entitlements on every set. A project's entitlement is defined as a ratio
47 +entitlements on every set.
48 +A project's entitlement is defined as a ratio
30 49 between the number of shares given to a project and the sum of shares of all
31 -active projects running on the same processor set. An active project is one
32 -that has at least one running or runnable process. Entitlements are recomputed
50 +active projects running on the same processor set.
51 +An active project is one
52 +that has at least one running or runnable process.
53 +Entitlements are recomputed
33 54 whenever any project becomes active or inactive, or whenever the number of
34 55 shares is changed.
35 -.sp
36 -.LP
56 +.Pp
37 57 Processor sets represent virtual machines in the FSS scheduling class and
38 -processes are scheduled independently in each processor set. That is, processes
58 +processes are scheduled independently in each processor set.
59 +That is, processes
39 60 compete with each other only if they are running on the same processor set.
40 61 When a processor set is destroyed, all processes that were bound to it are
41 -moved to the default processor set, which always exists. Empty processor sets
62 +moved to the default processor set, which always exists.
63 +Empty processor sets
42 64 (that is, sets without processors in them) have no impact on the FSS scheduler
43 65 behavior.
44 -.sp
45 -.LP
66 +.Pp
46 67 If a processor set contains a mix of TS/IA and FSS processes, the fairness of
47 68 the FSS scheduling class can be compromised because these classes use the same
48 -range of priorities. Fairness is most significantly affected if processes
69 +range of priorities.
70 +Fairness is most significantly affected if processes
49 71 running in the TS scheduling class are CPU-intensive and are bound to
50 -processors within the processor set. As a result, you should avoid having
51 -processes from TS/IA and FSS classes share the same processor set. RT and FSS
72 +processors within the processor set.
73 +As a result, you should avoid having
74 +processes from TS/IA and FSS classes share the same processor set.
75 +RT and FSS
52 76 processes use disjoint priority ranges and therefore can share processor sets.
53 -.sp
54 -.LP
55 -As projects execute, their CPU usage is accumulated over time. The FSS
77 +.Pp
78 +As projects execute, their CPU usage is accumulated over time.
79 +The FSS
56 80 scheduler periodically decays CPU usages of every project by multiplying it
57 81 with a decay factor, ensuring that more recent CPU usage has greater weight
58 -when taken into account for scheduling. The FSS scheduler continually adjusts
82 +when taken into account for scheduling.
83 +The FSS scheduler continually adjusts
59 84 priorities of all processes to make each project's relative CPU usage converge
60 85 with its entitlement.
61 -.sp
62 -.LP
86 +.Pp
63 87 While FSS is designed to fairly allocate cycles over a long-term time period,
64 88 it is possible that projects will not receive their allocated shares worth of
65 -CPU cycles due to uneven demand. This makes one-shot, instantaneous analysis of
89 +CPU cycles due to uneven demand.
90 +This makes one-shot, instantaneous analysis of
66 91 FSS performance data unreliable.
67 -.sp
68 -.LP
69 -Note that share is not the same as utilization. A project may be allocated 50%
70 -of the system, although on the average, it uses just 20%. Shares serve to cap a
92 +.Pp
93 +Note that share is not the same as utilization.
94 +A project may be allocated 50%
95 +of the system, although on the average, it uses just 20%.
96 +Shares serve to cap a
71 97 project's CPU usage only when there is competition from other projects running
72 -on the same processor set. When there is no competition, utilization may be
73 -larger than entitlement based on shares. Allocating a small share to a busy
98 +on the same processor set.
99 +When there is no competition, utilization may be
100 +larger than entitlement based on shares.
101 +Allocating a small share to a busy
74 102 project slows it down but does not prevent it from completing its work if the
75 103 system is not saturated.
76 -.sp
77 -.LP
104 +.Pp
78 105 The configuration of CPU shares is managed by the name server as a property of
79 -the \fBproject\fR(4) database. In the following example, an entry in the
80 -\fB/etc/project\fR file sets the number of shares for project \fBx-files\fR to
81 -10:
82 -.sp
83 -.in +2
84 -.nf
106 +the
107 +.Xr project 4
108 +database.
109 +In the following example, an entry in the
110 +.Pa /etc/project
111 +file sets the number of shares for project
112 +.Sy x-files
113 +to 10:
114 +.Bd -literal -offset 2n
85 115 x-files:100::::project.cpu-shares=(privileged,10,none)
86 -.fi
87 -.in -2
88 -
89 -.sp
90 -.LP
91 -Projects with undefined number of shares are given one share each. This means
92 -that such projects are treated with equal importance. Projects with 0 shares
116 +.Ed
117 +.Pp
118 +Projects with undefined number of shares are given one share each.
119 +This means
120 +that such projects are treated with equal importance.
121 +Projects with 0 shares
93 122 only run when there are no projects with non-zero shares competing for the same
94 -processor set. The maximum number of shares that can be assigned to one project
123 +processor set.
124 +The maximum number of shares that can be assigned to one project
95 125 is 65535.
96 -.sp
97 -.LP
98 -You can use the \fBprctl\fR(1) command to determine the current share
126 +.Pp
127 +You can use the
128 +.Xr prctl 1
129 +command to determine the current share
99 130 assignment for a given project:
100 -.sp
101 -.in +2
102 -.nf
131 +.Bd -literal -offset 2n
103 132 $ prctl -n project.cpu-shares -i project x-files
104 -.fi
105 -.in -2
106 -
107 -.sp
108 -.LP
133 +.Ed
134 +.Pp
109 135 or to change the amount of shares if you have root privileges:
110 -.sp
111 -.in +2
112 -.nf
136 +.Bd -literal -offset 2n
113 137 # prctl -r -n project.cpu-shares -v 5 -i project x-files
114 -.fi
115 -.in -2
116 -
117 -.sp
118 -.LP
119 -See the \fBprctl\fR(1) man page for additional information on how to modify and
138 +.Ed
139 +.Pp
140 +See the
141 +.Xr prctl 1
142 +man page for additional information on how to modify and
120 143 examine resource controls associated with active processes, tasks, or projects
121 -on the system. See \fBresource_controls\fR(5) for a description of the resource
144 +on the system.
145 +See
146 +.Xr resource_controls 5
147 +for a description of the resource
122 148 controls supported in the current release of the Solaris operating system.
123 -.sp
124 -.LP
125 -By default, project \fBsystem\fR (project ID 0) includes all system daemons
126 -started by initialization scripts and has an "unlimited" amount of shares. That
149 +.Pp
150 +By default, project
151 +.Sy system
152 +(project ID 0) includes all system daemons
153 +started by initialization scripts and has an
154 +.Dq unlimited
155 +amount of shares.
156 +That
127 157 is, it is always scheduled first no matter how many shares are given to other
128 158 projects.
129 -.sp
130 -.LP
159 +.Pp
131 160 The following command sets FSS as the default scheduler for the system:
132 -.sp
133 -.in +2
134 -.nf
161 +.Bd -literal -offset 2n
135 162 # dispadmin -d FSS
136 -.fi
137 -.in -2
138 -
139 -.sp
140 -.LP
141 -This change will take effect on the next reboot. Alternatively, you can move
163 +.Ed
164 +.Pp
165 +This change will take effect on the next reboot.
166 +Alternatively, you can move
142 167 processes from the time-share scheduling class (as well as the special case of
143 168 init) into the FSS class without changing your default scheduling class and
144 -rebooting by becoming \fBroot\fR, and then using the \fBpriocntl\fR(1) command,
145 -as shown in the following example:
146 -.sp
147 -.in +2
148 -.nf
169 +rebooting by becoming
170 +.Sy root ,
171 +and then using the
172 +.Xr priocntl 1
173 +command, as shown in the following example:
174 +.Bd -literal -offset 2n
149 175 # priocntl -s -c FSS -i class TS
150 176 # priocntl -s -c FSS -i pid 1
151 -.fi
152 -.in -2
153 -
154 -.SH CONFIGURING SCHEDULER WITH DISPADMIN
155 -.LP
156 -You can use the \fBdispadmin\fR(1M) command to examine and tune the FSS
157 -scheduler's time quantum value. Time quantum is the amount of time that a
158 -thread is allowed to run before it must relinquish the processor. The following
177 +.Ed
178 +.Sh CONFIGURING SCHEDULER WITH DISPADMIN
179 +You can use the
180 +.Xr dispadmin 1M
181 +command to examine and tune the FSS
182 +scheduler's time quantum value.
183 +Time quantum is the amount of time that a
184 +thread is allowed to run before it must relinquish the processor.
185 +The following
159 186 example dumps the current time quantum for the fair share scheduler:
160 -.sp
161 -.in +2
162 -.nf
187 +.Bd -literal -offset 2n
163 188 $ dispadmin -g -c FSS
164 189 #
165 190 # Fair Share Scheduler Configuration
166 191 #
167 192 RES=1000
168 193 #
169 194 # Time Quantum
170 195 #
171 196 QUANTUM=110
172 -.fi
173 -.in -2
174 -
175 -.sp
176 -.LP
197 +.Ed
198 +.Pp
177 199 The value of the QUANTUM represents some fraction of a second with the
178 -fractional value determined by the reciprocal value of RES. With the default
179 -value of RES = 1000, the reciprocal of 1000 is .001, or milliseconds. Thus, by
200 +fractional value determined by the reciprocal value of RES.
201 +With the default
202 +value of RES = 1000, the reciprocal of 1000 is \&.001, or milliseconds.
203 +Thus, by
180 204 default, the QUANTUM value represents the time quantum in milliseconds.
181 -.sp
182 -.LP
183 -If you change the RES value using \fBdispadmin\fR with the \fB-r\fR option, you
184 -also change the QUANTUM value. For example, instead of quantum of 110 with RES
185 -of 1000, a quantum of 11 with a RES of 100 results. The fractional unit is
186 -different while the amount of time is the same.
187 -.sp
188 -.LP
189 -You can use the \fB-s\fR option to change the time quantum value. Note that
190 -such changes are not preserved across reboot. Please refer to the
191 -\fBdispadmin\fR(1M) man page for additional information.
192 -
193 -.SH SEE ALSO
194 -.LP
195 -\fBprctl\fR(1), \fBpriocntl\fR(1), \fBdispadmin\fR(1M), \fBpsrset\fR(1M),
196 -\fBpriocntl\fR(2), \fBproject\fR(4), \fBresource_controls\fR(5)
197 -.sp
198 -.LP
199 -\fISystem Administration Guide: Virtualization Using the Solaris Operating
200 -System\fR
205 +.Pp
206 +If you change the RES value using
207 +.Xr dispadmin 1M
208 +with the
209 +.Fl r
210 +option, you also change the QUANTUM value.
211 +For example, instead of quantum of 110 with RES
212 +of 1000, a quantum of 11 with a RES of 100 results.
213 +The fractional unit is different while the amount of time is the same.
214 +.Pp
215 +You can use the
216 +.Fl s
217 +option to change the time quantum value.
218 +Note that such changes are not preserved across reboot.
219 +Please refer to the
220 +.Xr dispadmin 1M
221 +man page for additional information.
222 +.Sh SEE ALSO
223 +.Xr prctl 1 ,
224 +.Xr priocntl 1 ,
225 +.Xr dispadmin 1M ,
226 +.Xr psrset 1M ,
227 +.Xr priocntl 2 ,
228 +.Xr project 4 ,
229 +.Xr resource_controls 5
230 +.Pp
231 +.%T System Administration Guide: Virtualization Using the Solaris Operating System
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