From: Mike Galbraith <efault@gmx.de>
To: Thomas Pilarski <thomas.pi@arcor.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andrew Morton <akpm@linux-foundation.org>,
Gregory Haskins <ghaskins@novell.com>,
bugme-daemon@bugzilla.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [Bugme-new] [Bug 12562] New: High overhead while switching or synchronizing threads on different cores
Date: Fri, 30 Jan 2009 08:57:50 +0100 [thread overview]
Message-ID: <1233302270.6061.9.camel@marge.simson.net> (raw)
In-Reply-To: <1233237934.11129.183.camel@bugs-laptop>
On Thu, 2009-01-29 at 15:05 +0100, Thomas Pilarski wrote:
> > In short this program is carefully crafted to defeat all our affinity
> > tests - and I'm not sure what to do.
>
> I am sorry, although it is not carefully crafted. The function random()
> is causing my problem. I currently have no real data, so I tried to make
> some random utilization and data.
Yeah, rather big difference, mega-contention vs zero-contention.
2.6.28.2, profile of ThreadSchedulingIssue 4 524288 8 200
vma samples % app name symbol name
ffffffff80251efa 2574819 31.6774 vmlinux futex_wake
ffffffff80251a39 1367613 16.8255 vmlinux futex_wait
0000000000411790 815426 10.0320 ThreadSchedulingIssue random
ffffffff8022b3b5 343692 4.2284 vmlinux task_rq_lock
0000000000404e30 299316 3.6824 ThreadSchedulingIssue __lll_lock_wait_private
ffffffff8030d430 262906 3.2345 vmlinux copy_user_generic_string
ffffffff80462af2 235176 2.8933 vmlinux schedule
0000000000411b90 210984 2.5957 ThreadSchedulingIssue random_r
ffffffff80251730 129376 1.5917 vmlinux hash_futex
ffffffff8020be10 123548 1.5200 vmlinux system_call
ffffffff8020a679 119398 1.4689 vmlinux __switch_to
ffffffff8022f49b 110068 1.3541 vmlinux try_to_wake_up
ffffffff8024c4d1 106352 1.3084 vmlinux sched_clock_cpu
ffffffff8020be20 102709 1.2636 vmlinux system_call_after_swapgs
ffffffff80229a2d 100614 1.2378 vmlinux update_curr
ffffffff80248309 86475 1.0639 vmlinux add_wait_queue
ffffffff80253149 85969 1.0577 vmlinux do_futex
Versus using myrand() free sample cruft generator from rand(3) manpage. Poof.
vma samples % app name symbol name
004002f4 979506 90.7113 ThreadSchedulingIssue myrand
00400b00 53348 4.9405 ThreadSchedulingIssue thread_consumer
00400c25 42710 3.9553 ThreadSchedulingIssue thread_producer
One of those "don't _ever_ do that" things?
-Mike
next prev parent reply other threads:[~2009-01-30 7:58 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-12562-10286@http.bugzilla.kernel.org/>
2009-01-28 20:56 ` [Bugme-new] [Bug 12562] New: High overhead while switching or synchronizing threads on different cores Andrew Morton
2009-01-28 22:15 ` Peter Zijlstra
2009-01-28 22:25 ` Thomas Pilarski
2009-01-29 9:07 ` Peter Zijlstra
2009-01-29 10:12 ` Thomas Pilarski
2009-01-29 10:24 ` Thomas Pilarski
2009-01-29 10:31 ` Peter Zijlstra
2009-01-29 11:37 ` Peter Zijlstra
2009-01-29 14:05 ` Thomas Pilarski
2009-01-30 7:57 ` Mike Galbraith [this message]
2009-02-02 7:43 ` Thomas Pilarski
2009-02-02 8:19 ` Peter Zijlstra
2009-02-02 8:33 ` Thomas Pilarski
2009-02-02 8:52 ` Mike Galbraith
2009-02-02 8:55 ` Peter Zijlstra
2009-02-02 12:15 ` Peter Zijlstra
2009-02-02 18:29 ` Michael Kerrisk
2009-02-02 18:35 ` Peter Zijlstra
2009-02-03 4:55 ` Mike Galbraith
2009-02-03 3:56 ` Valdis.Kletnieks
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