Re: AIM7 40% regression with 2.6.26-rc1

!MAILaRCHIVE_VOTE_RePLACE
Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]
To: Zhang, Yanmin <yanmin_zhang@...>
Cc: Matthew Wilcox <matthew@...>, LKML <linux-kernel@...>, Alexander Viro <viro@...>, Linus Torvalds <torvalds@...>, Andrew Morton <akpm@...>
Date: Tuesday, May 6, 2008 - 7:44 am

* Zhang, Yanmin <yanmin_zhang@linux.intel.com> wrote:


hm, which exact semaphore would that be due to?

My first blind guess would be the BKL - there's not much other semaphore 
use left in the core kernel otherwise that would affect AIM7 normally. 
The VFS still makes frequent use of the BKL and AIM7 is very VFS 
intense. Getting rid of that BKL use from the VFS might be useful to 
performance anyway.

Could you try to check that it's indeed the BKL?

Easiest way to check it would be to run AIM7 it on 
sched-devel.git/latest and do scheduler tracing via:

   http://people.redhat.com/mingo/sched-devel.git/readme-tracer.txt

by doing:

   echo stacktrace > /debug/tracing/iter_ctl

you could get exact backtraces of all scheduling points in the trace. If 
the BKL's down() shows up in those traces then it's definitely the BKL 
that causes this. The backtraces will also tell us exactly which BKL use 
is the most frequent one.

To keep tracing overhead low on SMP i'd also suggest to only trace a 
single CPU, via:

  echo 1 > /debug/tracing/tracing_cpumask

	Ingo
--
Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]

Messages in current thread:
AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Tue May 6, 1:48 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Tue May 6, 7:44 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Tue May 6, 10:11 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Tue May 6, 11:41 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Andi Kleen, (Wed May 7, 7:00 am)
Re: AIM7 40% regression with 2.6.26-rc1, Alan Cox, (Wed May 7, 9:59 am)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Wed May 7, 7:46 am)
Re: AIM7 40% regression with 2.6.26-rc1, Andi Kleen, (Wed May 7, 8:21 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 10:36 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 12:20 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 12:35 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:05 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:24 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:36 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:55 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Wed May 7, 1:59 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 2:17 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 2:49 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 11:19 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Wed May 7, 10:44 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Thu May 8, 2:43 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Thu May 8, 3:14 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Thu May 8, 3:39 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Thu May 8, 4:44 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Thu May 8, 5:21 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Thu May 8, 5:30 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Thu May 8, 5:29 am)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Thu May 8, 2:48 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 11:29 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Thu May 8, 12:08 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Thu May 8, 12:17 am)
[git pull] scheduler fixes, Ingo Molnar, (Thu May 8, 11:10 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 7:03 am)
Re: [git pull] scheduler fixes, Sven Wegener, (Sun May 11, 10:10 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 9:01 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 9:06 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 9:45 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 7:48 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 8:50 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 8:52 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 9:02 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 9:54 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 10:22 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 10:32 am)
Re: [git pull] scheduler fixes, Linus Torvalds, (Sun May 11, 12:47 pm)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 10:46 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 9:26 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 10:00 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 10:18 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 10:42 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 10:48 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Sun May 11, 11:19 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 11:29 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Tue May 13, 10:11 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Tue May 13, 10:21 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Tue May 13, 10:42 am)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Tue May 13, 11:28 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Tue May 13, 1:13 pm)
Re: [git pull] scheduler fixes, Linus Torvalds, (Tue May 13, 1:22 pm)
Re: [git pull] scheduler fixes, Ingo Molnar, (Tue May 13, 5:05 pm)
Re: [git pull] scheduler fixes, Matthew Wilcox, (Sun May 11, 7:14 am)
Re: [git pull] scheduler fixes, Adrian Bunk, (Thu May 8, 11:33 am)
Re: [git pull] scheduler fixes, Ingo Molnar, (Thu May 8, 11:41 am)
Re: [git pull] scheduler fixes, Adrian Bunk, (Thu May 8, 3:42 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:14 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Andi Kleen, (Wed May 7, 10:57 am)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Wed May 7, 11:31 am)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Wed May 7, 12:22 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Alan Cox, (Wed May 7, 10:35 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 11:00 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 11:02 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 2:26 am)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 2:28 am)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Wed May 7, 3:05 am)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Tue May 6, 11:59 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Wed May 7, 12:46 am)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 8:09 am)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 12:23 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Wed May 7, 11:24 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 11:34 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Thu May 8, 12:37 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Thu May 8, 10:58 am)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Tue May 6, 1:21 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Wed May 7, 12:38 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 12:55 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:08 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:22 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:31 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:49 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 2:02 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 2:17 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 2:27 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 2:43 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 3:01 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Wed May 7, 3:24 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 3:44 pm)
Oi. NFS people. Read this., Matthew Wilcox, (Wed May 7, 4:00 pm)
Re: Oi. NFS people. Read this., Trond Myklebust, (Wed May 7, 6:10 pm)
Re: Oi. NFS people. Read this., J. Bruce Fields, (Thu May 8, 9:43 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 3:09 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:47 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Wed May 7, 1:25 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Wed May 7, 1:16 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Wed May 7, 1:27 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Tue May 6, 1:45 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Tue May 6, 1:39 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Zhang, Yanmin, (Wed May 7, 2:49 am)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 1:31 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Ingo Molnar, (Tue May 6, 1:49 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Andrew Morton, (Tue May 6, 2:07 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Sun May 11, 7:11 am)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Tue May 6, 12:36 pm)
Re: AIM7 40% regression with 2.6.26-rc1, J. Bruce Fields, (Tue May 6, 12:44 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 12:42 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Tue May 6, 4:28 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Alan Cox, (Tue May 6, 12:39 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 12:51 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Linus Torvalds, (Tue May 6, 1:42 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Alan Cox, (Tue May 6, 12:45 pm)
Re: AIM7 40% regression with 2.6.26-rc1, Matthew Wilcox, (Tue May 6, 7:18 am)