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Message-Id: <1287487757.24189.40.camel@marge.simson.net>
Date: Tue, 19 Oct 2010 13:29:17 +0200
From: Mike Galbraith <efault@....de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [RFC/RFT PATCH] sched: automated per tty task groups
It was suggested that I show a bit more info.
On Tue, 2010-10-19 at 11:16 +0200, Mike Galbraith wrote:
> A 100% hog overhead measurement proggy pinned to the same CPU as a make -j10
>
> pert/s: 229 >5484.43us: 41 min: 0.15 max:12069.42 avg:2193.81 sum/s:502382us overhead:50.24%
> pert/s: 222 >5652.28us: 43 min: 0.46 max:12077.31 avg:2248.56 sum/s:499181us overhead:49.92%
> pert/s: 211 >5809.38us: 43 min: 0.16 max:12064.78 avg:2381.70 sum/s:502538us overhead:50.25%
> pert/s: 223 >6147.92us: 43 min: 0.15 max:16107.46 avg:2282.17 sum/s:508925us overhead:50.49%
> pert/s: 218 >6252.64us: 43 min: 0.16 max:12066.13 avg:2324.11 sum/s:506656us overhead:50.27%
The same load without per tty task groups.
pert/s: 31 >40475.37us: 3 min: 0.37 max:48103.60 avg:29573.74 sum/s:916786us overhead:90.24%
pert/s: 23 >41237.70us: 12 min: 0.36 max:56010.39 avg:40187.01 sum/s:924301us overhead:91.99%
pert/s: 24 >42150.22us: 12 min: 8.86 max:61265.91 avg:39459.91 sum/s:947038us overhead:92.20%
pert/s: 26 >42344.91us: 11 min: 3.83 max:52029.60 avg:36164.70 sum/s:940282us overhead:91.12%
pert/s: 24 >44262.90us: 14 min: 5.05 max:82735.15 avg:40314.33 sum/s:967544us overhead:92.22%
^^^^^usecs ^^^^^usecs ^^the competition got
Average service latency is an order of magnitude better with tty_sched.
(Imagine that pert is Xorg or whatnot instead)
Using Mathieu Desnoyers' wakeup-latency testcase (attached):
With taskset -c 3 make -j 10 running..
taskset -c 3 ./wakeup-latency& sleep 30;killall wakeup-latency
without:
maximum latency: 42963.2 µs
average latency: 9077.0 µs
missed timer events: 0
with:
maximum latency: 4160.7 µs
average latency: 149.4 µs
missed timer events: 0
Patch makes a big difference in desktop feel under hefty load here.
-Mike
View attachment "wakeup-latency.c" of type "text/x-csrc" (7308 bytes)
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