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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.