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<title>cset-shield(1)</title>
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<body>
<div id="header">
<h1>
cset-shield(1) Manual Page
</h1>
<h2>NAME</h2>
<div class="sectionbody">
<p>cset-shield -
cpuset supercommand which implements cpu shielding
</p>
</div>
</div>
<h2>SYNOPSIS</h2>
<div class="sectionbody">
<div class="verseblock">
<div class="content"><em>cset</em> [cset options] <em>shield</em> [shield options] [args]
<em>cset</em> shield --help
<em>cset</em> shield
<em>cset</em> shield --cpu 1-7
<em>cset</em> shield --cpu 1-7 --kthread=on
<em>cset</em> shield --exec /opt/software/myapp/doit --my_opt1 --my_opt2
<em>cset</em> shield --user appuser --exec run_benchmark.sh
<em>cset</em> shield --shield 1024,2048,5000-1000
<em>cset</em> shield --unshield 6000-8500
<em>cset</em> shield --kthread=off
<em>cset</em> shield --kthread=on
<em>cset</em> shield --shield bash</div></div>
</div>
<h2>OPTIONS</h2>
<div class="sectionbody">
<dl>
<dt>
-h, --help
</dt>
<dd>
<p>
prints the list of options for this command
</p>
</dd>
<dt>
-c CPUSPEC, --cpu=CPUSPEC
</dt>
<dd>
<p>
modifies or initializes the shield cpusets
</p>
</dd>
<dt>
-r, --reset
</dt>
<dd>
<p>
destroys the shield
</p>
</dd>
<dt>
-e, --exec
</dt>
<dd>
<p>
executes args in the shield
</p>
</dd>
<dt>
--user=USER
</dt>
<dd>
<p>
use this USER for --exec (id or name)
</p>
</dd>
<dt>
--group=GROUP
</dt>
<dd>
<p>
use this GROUP for --exec (id or name)
</p>
</dd>
<dt>
-s PIDSPEC, --shield=PIDSPEC
</dt>
<dd>
<p>
shield specified PIDSPEC of processes or threads
</p>
</dd>
<dt>
-u PIDSPEC, --unshield=PIDSPEC
</dt>
<dd>
<p>
remove specified PIDSPEC of processes or threads from the shield,
the task keep running in the unshielded cpuset
</p>
</dd>
<dt>
-k on|off, --kthread=on|off
</dt>
<dd>
<p>
shield from unbound interrupt threads as well
</p>
</dd>
<dt>
-f, --force
</dt>
<dd>
<p>
force operation, use with care
</p>
</dd>
<dt>
-v, --verbose
</dt>
<dd>
<p>
prints more detailed output, additive
</p>
</dd>
<dt>
--sysset=SYSSET
</dt>
<dd>
<p>
optionally specify system cpuset name
</p>
</dd>
<dt>
--userset=USERSET
</dt>
<dd>
<p>
optionally specify user cpuset name
</p>
</dd>
</dl>
</div>
<h2>DESCRIPTION</h2>
<div class="sectionbody">
<p>This is a supercommand that creates basic cpu shielding. The
normal cset commands can of course be used to create this basic
shield, but the shield command combines many such commands to
create and manage a common type of cpu shielding setup.</p>
<p>The concept of shielding implies at minimum three cpusets, for
example: root, user and system. The root cpuset always exists in
all implementations of cpusets and contains all available CPUs on
the machine. The system cpuset is so named because normal system
tasks are made to run on it. The user cpuset is so named because
that is the "shielded" cpuset on which you would run your tasks
of interest.</p>
<p>Usually, CPU zero would be in the system set and the rest of the
CPUs would be in the user set. After creation of the cpusets,
all processes running in the root cpuset are moved to the system
cpuset. Thus any new processes or threads spawned from these
processes will also run the system cpuset.</p>
<p>If the optional --kthread=on option is given to the shield
command, then all kernel threads (with exception of the per-CPU
bound interrupt kernel threads) are also moved to the system set.</p>
<p>One executes processes on the shielded user cpuset with the
--exec subcommand or moves processes or threads to the shielded
cpuset with the --shield subcommand.</p>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">You do not need to specify which cpuset a process or thread
is running in initially when using the --shield subcommand.</td>
</tr></table>
</div>
<p>To create a shield, you would execute the shield command with the
--cpu option that specifies CPUSPEC argument that assigns CPUs to
be under the shield (this means assigned to the user cpuset, all
other cpus will be assigned to the system set).</p>
<p>For example:</p>
<p><strong><tt># cset shield --cpu=3</tt></strong></p>
<p>On a 4-way machine, this command will dedicate the first
3 processors, CPU0-CPU2, for the system set (unshielded)
and only the last processor, CPU3, for the user set
(shielded).</p>
<p>The CPUSPEC will accept a comma separated list of CPUs and
inclusive range specifications. For example, --cpu=1,3,5-7 will
assign CPU1, CPU3, CPU5, CPU6, and CPU7 to the user (or shielded)
cpuset.</p>
<p>If you do not like the names "system" and "user" for the
unshielded and shielded sets respectively, or if those names are
used already, then use the --sysset and --userset options.</p>
<p>For example:</p>
<p><strong><tt># cset shield --sysset=free --userset=cage --cpu=2,3 --kthread=on</tt></strong></p>
<p>The above command will use the name "free" for the unshielded
system cpuset, the name "cage" for the shielded user cpuset,
initialize these cpusets and dedicate CPU0 and CPU1 to the "free"
set and (on a 4-way machine) dedicate CPU2 and CPU3 to the "cage"
set. Further, the command moves all processes and threads,
including kernel threads from the root cpuset to the "free"
cpuset.</p>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">If you do use the --syset/--userset options, then you must
continue to use those for every invocation of the shield supercommand.</td>
</tr></table>
</div>
<p>After initialization, you can run the process of interest on the
shielded cpuset with the --exec subcommand, or move processes or
threads already running to the shielded cpuset with the --shield
subcommand.</p>
<p>The PIDSPEC argument taken for the --shield (or -s) subcommand is
a comma separated list of PIDs or TIDs. The list can also
include brackets of PIDs or TIDs that are inclusive of the
endpoints.</p>
<p>For example:</p>
<div class="literalblock">
<div class="content">
<pre><tt>1,2,5 Means processes 1, 2 and 5
1,2,600-700 Means processes 1, 2 and from 600 to 700</tt></pre>
</div></div>
<p><strong><tt># cset shield --shield=50-65</tt></strong></p>
<p>The above command moves all processes and threads with PID or
TID in the range 50-65 inclusive, from any cpuset they may
be running in into the shielded user cpuset.</p>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">The range of PIDs or TIDs does not need to have every
position populated. In other words, for the example above, if
there is only one process, say PID 57, in the range of 50-65,
then only that process will be moved.</td>
</tr></table>
</div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Caution</div>
</td>
<td class="content">Please note that there is no checking of processes you
request to move into the shield with the --shield command. This
means that the tool will happily move, for example, kernel
threads that are bound to specific CPUs with this command. You
can hang your system by indiscriminately specifying arbitrary
PIDs to the --shield command so please be careful.</td>
</tr></table>
</div>
<p>The --unshield (or -u) subcommand will remove the specified
processes or threads from the shielded cpuset and move them into
the unshielded (or system) cpuset. This option also takes a
PIDSPEC argument, the same as for the --shield subcommand.</p>
<p>Both the --shield and the --unshield commands will also finally
output the number of tasks running in the shield and out of the
shield. If you do not specify a PIDSPEC to these commands, then
just that status is output. By specifying also a --verbose in
addition, then you will get a listing of every task that is
running in either the shield or out of the shield.</p>
<p>Using no subcommand, ie. only "cset shield", will output the
status of both shield and non-shield. Tasks will be listed if
--verbose is used.</p>
<p>You can adjust which CPUs are in the shielded cpuset by issuing
the --cpu subcommand again anytime after the shield has been
initialized.</p>
<p>For example if the original shield contained CPU0 and CPU1 in the
system set and CPU2 and CPU3 in the user set, if you then issue
the following command:</p>
<p><strong><tt># cset shield --cpu=1,2,3</tt></strong></p>
<p>then that command will move CPU1 into the shielded "user" cpuset.
Any processes or threads that were running on CPU1 that belonged
to the unshielded "system" cpuset are migrated to CPU0 by the
system.</p>
<p>The --reset subcommand will in essence destroy the shield. For
example, if there was a shield on a 4-way machine with CPU0 in
system and CPUs 1-3 in user with processes running on the user
cpuset (i.e. in the shield), and a --reset subcommand was issued,
then all processes running in both system and user cpusets would
be migrated to the root cpuset (which has access to all CPUs and
never goes away), after which both system and user cpusets would
be destroyed.</p>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">Even though you can mix general usage of cpusets with
the shielding concepts described here, you generally will not
want to. For more complex shielding or usage scenarios, one
would generally use the normal cpuset commands (i.e. cset set
and proc) directly.</td>
</tr></table>
</div>
</div>
<h2>LICENSE</h2>
<div class="sectionbody">
<p>Cpuset is licensed under the GNU GPL V2 only.</p>
</div>
<h2>COPYRIGHT</h2>
<div class="sectionbody">
<p>Copyright (c) 2008 Novell Inc.</p>
</div>
<h2>AUTHOR</h2>
<div class="sectionbody">
<p>Written by Alex Tsariounov &lt;alext@novell.com&gt;.</p>
<p>Some substrate code and ideas were taken from the excellent Stacked
GIT (stgit) v0.13 (see http://gna.org/projects/stgit and
http://www.procode.org/stgit). Stacked GIT is under GPL V2 or later.</p>
</div>
<h2>SEE ALSO</h2>
<div class="sectionbody">
<p><a href="cset.html">cset(1)</a>, <a href="cset-set.html">cset-set(1)</a>, <a href="cset-proc.html">cset-proc(1)</a>, <a href="taskset.html">taskset(1)</a>,
<a href="chrt.html">chrt(1)</a></p>
<p>/usr/src/linux/Documentation/cpusets.txt</p>
</div>
<div id="footer">
<div id="footer-text">
Version 1.0<br />
Last updated 30-May-2008 14:33:24 MDT
</div>
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