From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932510AbWDOWqF (ORCPT ); Sat, 15 Apr 2006 18:46:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932512AbWDOWqF (ORCPT ); Sat, 15 Apr 2006 18:46:05 -0400 Received: from smtp.osdl.org ([65.172.181.4]:6322 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S932510AbWDOWqD (ORCPT ); Sat, 15 Apr 2006 18:46:03 -0400 Date: Sat, 15 Apr 2006 15:45:18 -0700 From: Andrew Morton To: "Martin J. Bligh" Cc: linux-kernel@vger.kernel.org, apw@shadowen.org, Ingo Molnar Subject: Re: Clear performance regression on reaim7 in 2.6.15-git6 Message-Id: <20060415154518.6a5a0c52.akpm@osdl.org> In-Reply-To: <444173EE.4060602@google.com> References: <4441452F.3060009@google.com> <20060415141744.042231a8.akpm@osdl.org> <44416616.10908@google.com> <20060415145227.5d1249bd.akpm@osdl.org> <444173EE.4060602@google.com> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org "Martin J. Bligh" wrote: > > Andrew Morton wrote: > > "Martin J. Bligh" wrote: > > > >>drilling down into the results directories can get you the command line, > >> looks like "reaim -f workfile.short -s 1 -e 10 -i 2" to me. Buggered if > >> I can recall what that did though. > >> > >> (http://test.kernel.org/abat/20229/004.reaim.test/results/cmdline) > >> > >> I *think* it's only ia32 NUMA boxes, at least as far as I can see from > >> a quick poke around. Which would make me guess at scheduler code. Gitweb > >> would be nice to use, but it doesn't tag the -git snapshots, AFAICS, > >> which is a real shame. Nor does the git snapshot include the git tag, > >> as far as I know. Grrrr. I guess I'll download the snapshots and diff > >> them, and try to pull out the sched changes by hand. Much suckage. > > > > > > The diffstat for 2.6.15-git5 -> 2.6.15-git6 is at > > http://www.zip.com.au/~akpm/linux/patches/stuff/2 - only a single line > > changed in sched.c: > > > > diff -uNr 2.6.15-git5/kernel/sched.c 2.6.15-git6/kernel/sched.c > > --- 2.6.15-git5/kernel/sched.c 2006-04-15 14:10:43.000000000 -0700 > > +++ 2.6.15-git6/kernel/sched.c 2006-04-15 14:10:52.000000000 -0700 > > @@ -4386,6 +4386,7 @@ > > } while_each_thread(g, p); > > > > read_unlock(&tasklist_lock); > > + mutex_debug_show_all_locks(); > > } > > Hmm. whilst it's probably not that call, it does look like mutex > debugging. Look at the profiles from reaim between -git5 and -git6: > > before: > http://test.kernel.org/abat/20115/004.reaim.test/profiling/profile.text > > after: > http://test.kernel.org/abat/20229/004.reaim.test/profiling/profile.text > > 1262 kfree 3.5056 > 820 mutex_lock_interruptible 164.0000 > 752 __mutex_lock_slowpath 0.8754 > 43 schedule 0.0284 > 35 _spin_lock 2.3333 > 25 debug_mutex_set_owner 0.1613 > 23 debug_mutex_add_waiter 0.1586 hm. > /me hugs his huge stacks of data. > > -------------------------------- > > config DEBUG_MUTEXES > bool "Mutex debugging, deadlock detection" > default y > depends on DEBUG_KERNEL > help > This allows mutex semantics violations and mutex related deadlocks > (lockups) to be detected and reported automatically. > > -------------------------------- > > Hmmm. Who the hell thought defaulting that to 'y' was a good plan???? Ingo ;) > It's still broken in 17-rc1 ... will send you a patch in a sec. I already have kconfigdebug-set-debug_mutex-to-off-by-default.patch queued up.