linux-kernel - Example program for PRIO

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Date:	Fri, 11 Mar 2016 11:05:22 -0500
From:	Tejun Heo <tj@...nel.org>
To:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	a.p.zijlstra@...llo.nl, mingo@...hat.com, lizefan@...wei.com,
	hannes@...xchg.org, pjt@...gle.com
Cc:	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
	linux-api@...r.kernel.org, kernel-team@...com
Subject: Example program for PRIO_RGRP

Hello,

The attached test-rgrp-burn.c is an example program making use of the
new PRIO_RGRP.  The test program creates rgroup the following rgroup
hierarchy

 sgroup - main thread
        + [rgroup-0] burner-0
        + [rgroup-1] + [rgroup-2] burner-1
                     + [rgroup-3] burner-2

and takes upto 4 arguments respectively specifying the nice level for
each rgroup.  Each burner thread executes CPU burning loops and
periodically prints out how many loops it has completed.

* "./test-rgrp-burn"

If the program is run without any argument, on a kernel which doesn't
support rgroup, or from a cgroup where cpu controller is not
available, the three burner threads would run at about equivalent
speeds.

* "./test-rgrp-burn 0" from a cgroup w/ cpu controller

cpu controller is enabled across the top-level, so rgroup-0 and
rgroup-1 would compete on equal footing, so burner-0 runs twice as
fast as burner-1 or burner-2.

* "./test-rgrp-burn 0 3 -1 2" from a cgroup w/ cpu controller

cpu controller is enabled at both levels.  Nice level difference of 3
is about twice difference in weight, so the ratio would roughly be

  burner-0 : burner-1 : burner-2 ~= 3 : 2 : 1

Thanks.

-- 
tejun

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