From: Peter Zijlstra <peterz@infradead.org>
To: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [regression] cross core scheduling frequency drop bisected to 0c313cb20732
Date: Fri, 8 Apr 2016 08:45:10 +0200 [thread overview]
Message-ID: <20160408064510.GK3448@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1460092854.4051.1.camel@gmail.com>
On Fri, Apr 08, 2016 at 07:20:54AM +0200, Mike Galbraith wrote:
> Greetings,
>
> While measuring current NO_HZ cost to light tasks jabbering cross core
> at high frequency (~7% max), I noticed that master lost an improvement
> for same acquired in 4.5, so bisected it.
>
> 4.5.0
> homer:~ # taskset 0xc pipe-test 1
> 2.367681 usecs/loop -- avg 2.367681 844.7 KHz
> 2.372502 usecs/loop -- avg 2.368163 844.5 KHz
> 2.342506 usecs/loop -- avg 2.365597 845.5 KHz
> 2.383029 usecs/loop -- avg 2.367341 844.8 KHz
> 2.321859 usecs/loop -- avg 2.362792 846.5 KHz 1.00
>
> master
> homer:~ # taskset 0xc pipe-test 1
> 2.797656 usecs/loop -- avg 2.797656 714.9 KHz
> 2.804518 usecs/loop -- avg 2.798342 714.7 KHz
> 2.804206 usecs/loop -- avg 2.798929 714.6 KHz
> 2.802887 usecs/loop -- avg 2.799324 714.5 KHz
> 2.801577 usecs/loop -- avg 2.799550 714.4 KHz 0.84
>
> master 0c313cb20732 reverted
> homer:~ # !taskset
> homer:~ # taskset 0xc pipe-test 1
> 2.277494 usecs/loop -- avg 2.277494 878.2 KHz
> 2.320979 usecs/loop -- avg 2.281843 876.5 KHz
> 2.272750 usecs/loop -- avg 2.280933 876.8 KHz
> 2.272209 usecs/loop -- avg 2.280061 877.2 KHz
> 2.277279 usecs/loop -- avg 2.279783 877.3 KHz 1.03
>
> 0c313cb207326f759a58f486214288411b25d4cf is the first bad commit
> commit 0c313cb207326f759a58f486214288411b25d4cf
> Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Date: Sun Mar 20 01:33:35 2016 +0100
>
> cpuidle: menu: Fall back to polling if next timer event is near
>
Cute, I thought you used governor=performance for your runs?
next prev parent reply other threads:[~2016-04-08 6:45 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-08 5:20 [regression] cross core scheduling frequency drop bisected to 0c313cb20732 Mike Galbraith
2016-04-08 6:45 ` Peter Zijlstra [this message]
2016-04-08 6:50 ` Mike Galbraith
2016-04-08 20:59 ` Rafael J. Wysocki
2016-04-08 22:19 ` Doug Smythies
2016-04-09 6:44 ` Mike Galbraith
2016-04-09 7:17 ` Doug Smythies
2016-04-09 7:27 ` Mike Galbraith
2016-04-09 11:08 ` Peter Zijlstra
2016-04-09 6:40 ` Mike Galbraith
2016-04-09 12:33 ` Rafael J. Wysocki
2016-04-09 15:10 ` Mike Galbraith
2016-04-09 16:39 ` Mike Galbraith
2016-04-10 3:44 ` Rafael J. Wysocki
2016-04-10 7:16 ` Doug Smythies
2016-04-10 9:35 ` Mike Galbraith
2016-04-10 14:54 ` Mike Galbraith
2016-04-09 11:07 ` Peter Zijlstra
2016-04-09 12:31 ` Rafael J. Wysocki
2016-04-10 15:39 ` Mike Galbraith
2016-04-10 20:24 ` Rik van Riel
2016-04-11 3:04 ` Mike Galbraith
2016-04-11 12:38 ` Rik van Riel
2016-04-11 13:21 ` Rafael J. Wysocki
2016-04-11 13:38 ` Rik van Riel
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160408064510.GK3448@twins.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rafael.j.wysocki@intel.com \
--cc=umgwanakikbuti@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox