Sergey Aleynikov > BSD-Process-Affinity > BSD::Process::Affinity

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NAME ^

BSD::Process::Affinity - Manipulate CPU affinities on FreeBSD

SYNOPSIS ^

        use BSD::Process::Affinity;
        BSD::Process::Affinity->get_process_mask()->set(0x2)->update();

VERSION INCOMPABILITY ^

Version 0.4 has API partly incompatible with previous releases. Here are differences:

DESCRIPTION ^

Ability to manage CPU affinities from userland was a long-awaited feature in FreeBSD, and it is finally available since 7.1 release. This module allows you to programmatically manipulate them from perl level.

FreeBSD gives you three levels of restricting CPUs for a single process/thread:

Beware, when manipulating affinities, you may degrade performance instead of gaining it.

INTERFACE ^

To operate with this module, you should do three steps:

Here is an example that makes current thread NOT to run on 2nd processor in system:

        use BSD::Process::Affinity;
        my $obj = BSD::Process::Affinity->get_thread_mask();
        $obj->set($obj->get() & ~0x2)->update();

Note the chainable ability of update.

Whenever any error occurs, this module croaks.

Get Affinity object ^

All these methods (except for clone) expects one parameter - an id of object you want to fetch affinity of. You can just ommit it - this means 'give data for the current process/thread/whatever'.

clone

Clones current process'es effective set, and makes current process member of just created set.

rootof_set

Gets 'root' set for a given set id.

rootof_pid

Gets 'root' set for a given process id.

current_set

Gets set content by given set id.

current_pid

Gets effetive set for a given process id.

get_thread_mask

Get anonymous mask for a given thread id (not perl's thread id, but a system thread id).

get_process_mask

Get anonymous mask for a given process id.

Processors' mask manipulation ^

Here are existing Affinity object methods.

update

        $affinity->update();

Writes back to kernel changes made in set content. Without this call, your changes does not affect anything.

assign

        $affinity->assign($pid);

Assigns set specifiyed in $affinity object to be an effective set for process $pid.

It is an error to apply this method to anonymous masks.

get_cpusetid

        my $n = $affinity->get_cpusetid();

Returns cpu set internal id - for usage with rootof_set/current_set. Returns zero for anonymous masks.

get

        my $value = $affinity->get();

Returns usigned integer representing current mask. Then you can perform any actions with it, and set it back using set method. Lowest (rightmost) bit represents CPU0, and so on.

set

        $affinity->set(0x5);  #run on CPU0 and CPU2

Loads mask represented by $mask into object. Note that you have to call update to save changes to kernel, that is not done automatically.

Mask is treated as an unsigned integer, so number of processor it can represent depends on OS arccitecture - 32 or 64 bits.

This method is chainable with update.

SEE ALSO ^

http://www.freebsd.org/cgi/man.cgi?query=cpuset_getaffinity

http://www.freebsd.org/cgi/man.cgi?query=cpuset

AUTHOR ^

Sergey Aleynikov <sergey.aleynikov@gmail.com>

LICENSE ^

Copyright (c) 2009, 2011 by Sergey Aleynikov. All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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