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From: Andrea Arcangeli <andrea@suse.de>
To: Nick Piggin <nickpiggin@yahoo.com.au>
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 10:45:59 +0100	[thread overview]
Message-ID: <20070313094559.GC8992@v2.random> (raw)
In-Reply-To: <45F63266.1080509@yahoo.com.au>

On Tue, Mar 13, 2007 at 04:11:02PM +1100, Nick Piggin wrote:
> Hi Anton,
> 
> Very cool. Yeah I had come to the conclusion that it wasn't a kernel
> issue, and basically was afraid to look into userspace ;)

btw, regardless of what glibc is doing, still the cpu shouldn't go
idle IMHO. Even if we're overscheduling and trashing over the mmap_sem
with threads (no idea if other OS schedules the task away when they
find the other cpu in the mmap critical section), or if we've
overscheduling with futex locking, the cpu usage should remain 100%
system time in the worst case. The only explanation for going idle
legitimately could be on HT cpus where HT may hurt more than help but
on real multicore it shouldn't happen.

  reply	other threads:[~2007-03-13  9:46 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-25 17:44 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 [this message]
2007-03-13 10:06           ` Nick Piggin
2007-03-13 10:31             ` Andrea Arcangeli
2007-03-13 10:37               ` Nick Piggin
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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