From: Mel Gorman <mgorman@suse.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Borislav Petkov <bp@alien8.de>,
Nikolay Ulyanitsky <lystor@gmail.com>,
Mike Galbraith <efault@gmx.de>,
linux-kernel@vger.kernel.org,
Andreas Herrmann <andreas.herrmann3@amd.com>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Suresh Siddha <suresh.b.siddha@intel.com>
Subject: Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to 3.6-rc5 on AMD chipsets - bisected
Date: Tue, 25 Sep 2012 14:23:13 +0100 [thread overview]
Message-ID: <20120925132312.GG11266@suse.de> (raw)
In-Reply-To: <1348508657.11847.114.camel@twins>
On Mon, Sep 24, 2012 at 07:44:17PM +0200, Peter Zijlstra wrote:
> On Mon, 2012-09-24 at 18:54 +0200, Peter Zijlstra wrote:
> > But let me try and come up with the list thing, I think we've
> > actually got that someplace as well.
>
> OK, I'm sure the below can be written better, but my brain is gone for
> the day...
>
It crashes on boot due to the fact that you created a function-scope variable
called sd_llc in select_idle_sibling() and shadowed the actual sd_llc you
were interested in. Result: dereferenced uninitialised pointer and kaboom.
Trivial to fix so it boots at least.
This is a silly test for a scheduler patch but as "sched: Avoid SMT siblings
in select_idle_sibling() if possible" regressed 2% back in 3.2, it seemed
reasonable to retest with it.
KERNBENCH
3.6.0 3.6.0 3.6.0
rc6-vanilla rc6-mikebuddy-v1r1 rc6-idlesibling-v1r1
User min 352.47 ( 0.00%) 351.77 ( 0.20%) 352.30 ( 0.05%)
User mean 353.10 ( 0.00%) 352.78 ( 0.09%) 352.77 ( 0.09%)
User stddev 0.41 ( 0.00%) 0.56 (-36.13%) 0.35 ( 15.16%)
User max 353.55 ( 0.00%) 353.43 ( 0.03%) 353.31 ( 0.07%)
System min 34.86 ( 0.00%) 34.83 ( 0.09%) 35.37 ( -1.46%)
System mean 35.35 ( 0.00%) 35.29 ( 0.16%) 35.63 ( -0.80%)
System stddev 0.41 ( 0.00%) 0.40 ( 0.10%) 0.15 ( 62.26%)
System max 35.94 ( 0.00%) 36.05 ( -0.31%) 35.81 ( 0.36%)
Elapsed min 110.18 ( 0.00%) 109.65 ( 0.48%) 110.04 ( 0.13%)
Elapsed mean 110.21 ( 0.00%) 109.75 ( 0.42%) 110.15 ( 0.06%)
Elapsed stddev 0.03 ( 0.00%) 0.07 (-167.83%) 0.09 (-207.56%)
Elapsed max 110.26 ( 0.00%) 109.86 ( 0.36%) 110.26 ( 0.00%)
CPU min 352.00 ( 0.00%) 353.00 ( -0.28%) 352.00 ( 0.00%)
CPU mean 352.00 ( 0.00%) 353.00 ( -0.28%) 352.00 ( 0.00%)
CPU stddev 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
CPU max 352.00 ( 0.00%) 353.00 ( -0.28%) 352.00 ( 0.00%)
mikebuddy-v1r1 is Mike's patch that just got reverted. idlesibling is
Peters patch. "Elapsed mean" time is the main value of interest. Mike's
patch gains 0.42% which is less than the 2% lost but at least the gain is
outside the noise. idlesibling make very little difference. "System mean"
is also interesting because even though idlesibling shows a "regression", it
also shows that the variation between runs is reduced. That might indicate
that fewer cache misses are being incurred in the select_idle_sibling()
code although that is a bit of a leap of faith.
The machine is in use at the moment but I'll queue up a test this evening to
gather a profile to confirm time is even being spent in select_idle_sibling()
Just because 2% was lost in select_idle_sibling() back in 3.2 does not
mean squat now.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2012-09-25 13:23 UTC|newest]
Thread overview: 115+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-14 7:47 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to 3.6-rc5 on AMD chipsets Nikolay Ulyanitsky
2012-09-14 18:40 ` Borislav Petkov
2012-09-14 18:51 ` Borislav Petkov
2012-09-14 21:27 ` 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to 3.6-rc5 on AMD chipsets - bisected Borislav Petkov
2012-09-14 21:40 ` Peter Zijlstra
2012-09-14 21:44 ` Linus Torvalds
2012-09-14 21:56 ` Peter Zijlstra
2012-09-14 21:59 ` Peter Zijlstra
2012-09-15 3:57 ` Mike Galbraith
2012-09-14 22:01 ` Linus Torvalds
2012-09-14 22:10 ` Peter Zijlstra
2012-09-14 22:20 ` Linus Torvalds
2012-09-14 22:14 ` Borislav Petkov
2012-09-14 21:45 ` Borislav Petkov
2012-09-14 21:42 ` Linus Torvalds
2012-09-15 3:33 ` Mike Galbraith
2012-09-15 16:16 ` Andi Kleen
2012-09-15 16:36 ` Mike Galbraith
2012-09-15 17:08 ` richard -rw- weinberger
2012-09-16 4:48 ` Mike Galbraith
2012-09-15 21:32 ` Alan Cox
2012-09-16 4:35 ` Mike Galbraith
2012-09-16 19:57 ` Linus Torvalds
2012-09-17 8:08 ` Mike Galbraith
2012-09-17 10:07 ` Ingo Molnar
2012-09-17 10:47 ` Mike Galbraith
2012-09-17 14:39 ` Andi Kleen
2012-09-19 12:35 ` Mike Galbraith
2012-09-19 14:54 ` Ingo Molnar
2012-09-19 15:23 ` Mike Galbraith
2012-09-24 15:00 ` Mel Gorman
2012-09-24 15:23 ` Nikolay Ulyanitsky
2012-09-24 15:53 ` Borislav Petkov
2012-09-24 15:30 ` Peter Zijlstra
2012-09-24 15:51 ` Mike Galbraith
2012-09-24 15:52 ` Linus Torvalds
2012-09-24 16:07 ` Peter Zijlstra
2012-09-24 16:33 ` Linus Torvalds
2012-09-24 16:54 ` Peter Zijlstra
2012-09-25 12:10 ` Hillf Danton
2012-09-24 16:12 ` Peter Zijlstra
2012-09-24 16:30 ` Linus Torvalds
2012-09-24 16:52 ` Borislav Petkov
2012-09-24 16:54 ` Peter Zijlstra
2012-09-24 17:44 ` Peter Zijlstra
2012-09-25 13:23 ` Mel Gorman [this message]
2012-09-25 14:36 ` Peter Zijlstra
2012-09-24 18:26 ` Mike Galbraith
2012-09-24 19:12 ` Linus Torvalds
2012-09-24 19:20 ` Borislav Petkov
2012-09-25 1:57 ` Mike Galbraith
2012-09-25 2:11 ` Linus Torvalds
2012-09-25 2:49 ` Mike Galbraith
2012-09-25 3:10 ` Linus Torvalds
2012-09-25 3:20 ` Mike Galbraith
2012-09-25 3:32 ` Linus Torvalds
2012-09-25 3:43 ` Mike Galbraith
2012-09-25 11:58 ` Peter Zijlstra
2012-09-25 13:17 ` Borislav Petkov
2012-09-25 17:00 ` Borislav Petkov
2012-09-25 17:21 ` Linus Torvalds
2012-09-25 18:42 ` Borislav Petkov
2012-09-25 19:08 ` Linus Torvalds
2012-09-26 2:23 ` Mike Galbraith
2012-09-26 17:17 ` Borislav Petkov
2012-09-26 2:00 ` Mike Galbraith
2012-09-26 2:22 ` Linus Torvalds
2012-09-26 2:42 ` Mike Galbraith
2012-09-26 17:15 ` Borislav Petkov
2012-09-26 16:32 ` Borislav Petkov
2012-09-26 18:19 ` Linus Torvalds
2012-09-26 21:37 ` Borislav Petkov
2012-09-27 5:09 ` Mike Galbraith
2012-09-27 5:18 ` Borislav Petkov
2012-09-27 5:44 ` Mike Galbraith
2012-09-27 5:47 ` Ingo Molnar
2012-09-27 5:59 ` Ingo Molnar
2012-09-27 6:34 ` Mike Galbraith
2012-09-27 6:41 ` Ingo Molnar
2012-09-27 6:54 ` Mike Galbraith
2012-09-27 7:10 ` Ingo Molnar
2012-09-27 16:25 ` Borislav Petkov
2012-09-27 17:44 ` Linus Torvalds
2012-09-27 18:05 ` Borislav Petkov
2012-09-27 18:19 ` Linus Torvalds
2012-09-27 18:29 ` Peter Zijlstra
2012-09-27 19:24 ` Borislav Petkov
2012-09-28 3:50 ` Mike Galbraith
2012-09-28 12:30 ` Borislav Petkov
2012-09-27 19:40 ` Linus Torvalds
2012-09-28 4:13 ` Mike Galbraith
2012-09-28 8:37 ` Peter Zijlstra
2012-09-27 7:17 ` david
2012-09-27 7:55 ` Mike Galbraith
2012-09-27 10:20 ` Borislav Petkov
2012-09-27 13:38 ` Mike Galbraith
2012-09-27 16:55 ` david
2012-09-27 4:32 ` Mike Galbraith
2012-09-27 8:21 ` Peter Zijlstra
2012-09-27 16:48 ` david
2012-09-27 17:38 ` Peter Zijlstra
2012-09-27 17:45 ` david
2012-09-27 18:09 ` Peter Zijlstra
2012-09-27 18:15 ` Linus Torvalds
2012-09-27 18:24 ` Borislav Petkov
2012-09-25 1:39 ` Mike Galbraith
2012-09-25 21:11 ` Suresh Siddha
2012-09-25 4:16 ` Mike Galbraith
2012-09-15 4:11 ` Mike Galbraith
[not found] ` <CA+55aFz1A7HbMYS9o-GTS5Zm=Xx8MUD7cR05GMVo--2E34jcgQ@mail.gmail.com>
2012-09-15 4:42 ` Mike Galbraith
2012-09-15 10:44 ` Borislav Petkov
2012-09-15 14:47 ` Mike Galbraith
2012-09-15 15:18 ` Borislav Petkov
2012-09-15 16:13 ` Mike Galbraith
2012-09-15 19:44 ` Borislav Petkov
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=20120925132312.GG11266@suse.de \
--to=mgorman@suse.de \
--cc=akpm@linux-foundation.org \
--cc=andreas.herrmann3@amd.com \
--cc=bp@alien8.de \
--cc=efault@gmx.de \
--cc=linux-kernel@vger.kernel.org \
--cc=lystor@gmail.com \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=suresh.b.siddha@intel.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/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