From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Anton Blanchard <anton@samba.org>, Rik van Riel <riel@redhat.com>,
Lorenzo Allegrucci <l_allegrucci@yahoo.it>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Suparna Bhattacharya <suparna@in.ibm.com>,
Jens Axboe <jens.axboe@oracle.com>
Subject: Re: SMP performance degradation with sysbench
Date: Tue, 13 Mar 2007 21:37:54 +1100 [thread overview]
Message-ID: <45F67F02.5020401@yahoo.com.au> (raw)
In-Reply-To: <20070313103134.GF8992@v2.random>
Andrea Arcangeli wrote:
> On Tue, Mar 13, 2007 at 09:06:14PM +1100, Nick Piggin wrote:
>
>>Well ignoring the HT issue, I was seeing lots of idle time simply
>>because userspace could not keep up enough load to the scheduler.
>>There simply were fewer runnable tasks than CPU cores.
>
>
> When you said idle I thought idle and not waiting for I/O. Waiting for
> I/O would be hardly a kernel issue ;). If they're not waiting for I/O
> and they're not scheduling in userland with nanosleep/pause, the cpu
> shouldn't go idle. Even if they're calling sched_yield in a loop the
> cpu should account for zero idle time as far as I can tell.
Well it wasn't iowait time. From Anton's analysis, I would probably
say it was time waiting for either the glibc malloc mutex or MySQL
heap mutex.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2007-03-13 10:38 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-25 17:44 SMP performance degradation with sysbench Lorenzo Allegrucci
2007-02-25 23:46 ` Rik van Riel
2007-02-26 13:36 ` Nick Piggin
2007-02-26 13:41 ` Nick Piggin
2007-02-26 22:04 ` Pete Harlan
2007-02-26 22:36 ` Dave Jones
2007-02-27 0:32 ` Hiro Yoshioka
2007-02-27 0:43 ` Rik van Riel
2007-02-27 4:03 ` Hiro Yoshioka
2007-02-27 4:31 ` Rik van Riel
2007-02-27 8:14 ` J.A. Magallón
2007-02-27 14:02 ` Rik van Riel
2007-02-27 14:56 ` Paulo Marques
2007-02-27 20:40 ` Nish Aravamudan
2007-02-28 2:21 ` Bill Davidsen
2007-02-28 2:52 ` Nish Aravamudan
2007-03-01 0:20 ` Nish Aravamudan
2007-02-27 19:05 ` Lorenzo Allegrucci
2007-03-01 16:57 ` Lorenzo Allegrucci
2007-02-28 1:27 ` Nish Aravamudan
2007-02-28 2:22 ` Nick Piggin
2007-02-28 2:51 ` Nish Aravamudan
2007-03-12 22:00 ` Anton Blanchard
2007-03-13 5:11 ` Nick Piggin
2007-03-13 9:45 ` Andrea Arcangeli
2007-03-13 10:06 ` Nick Piggin
2007-03-13 10:31 ` Andrea Arcangeli
2007-03-13 10:37 ` Nick Piggin [this message]
2007-03-13 10:57 ` Andrea Arcangeli
2007-03-13 11:12 ` Nick Piggin
2007-03-13 11:40 ` Eric Dumazet
2007-03-13 11:56 ` Nick Piggin
2007-03-13 11:42 ` Andrea Arcangeli
2007-03-13 12:02 ` Eric Dumazet
2007-03-13 12:27 ` Jakub Jelinek
2007-03-13 12:08 ` Nick Piggin
2007-03-14 23:33 ` Siddha, Suresh B
2007-03-20 2:29 ` Zhang, Yanmin
2007-04-02 2:59 ` Zhang, Yanmin
2007-03-13 6:00 ` Eric Dumazet
2007-03-14 0:36 ` Nish Aravamudan
2007-03-14 1:00 ` Eric Dumazet
2007-03-14 1:09 ` Nish Aravamudan
[not found] <fa.V3M3ZgXL+lFlIyhx43YxCU/JFUk@ifi.uio.no>
[not found] ` <fa.ciL5lzdfskdJHJPgn+UVCHt/9EM@ifi.uio.no>
[not found] ` <fa.2ABbHhyCbp3Fx7hSE/Gr0SuzFvw@ifi.uio.no>
[not found] ` <fa.oaZk6Aiqd8gyZNsj7+m+w9MibhU@ifi.uio.no>
[not found] ` <fa.RjX9Y4ckjRCle5L+uWNdd0snOio@ifi.uio.no>
[not found] ` <fa.XocsudxlGplKh0kloTtA0juPwtA@ifi.uio.no>
2007-02-28 0:20 ` Robert Hancock
2007-02-28 1:32 ` Hiro Yoshioka
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