From: Ingo Molnar <mingo@elte.hu>
To: Mark_H_Johnson@raytheon.com
Cc: Thomas Charbonnel <thomas@undata.org>,
"K.R. Foley" <kr@cybsft.com>,
linux-kernel@vger.kernel.org, Lee Revell <rlrevell@joe-job.com>
Subject: Re: [patch] voluntary-preempt-2.6.9-rc1-bk4-Q7
Date: Thu, 2 Sep 2004 07:34:45 +0200 [thread overview]
Message-ID: <20040902053445.GA12499@elte.hu> (raw)
In-Reply-To: <OFA48649D2.721211FD-ON86256F02.007CEFE1@raytheon.com>
* Mark_H_Johnson@raytheon.com <Mark_H_Johnson@raytheon.com> wrote:
> One place where we may need to consider more mcount() calls is in the
> scheduler. I got another 500+ msec trace going from dequeue_task to
> __switch_to.
(you mean 500+ usec, correct?)
there's no way the scheduler can have 500 usecs of overhead going from
dequeue_task() to __switch_to(): we have all interrupts disabled and
take zero locks! This is almost certainly some hardware effect (i
described some possibilities and tests a couple of mails earlier).
In any case, please enable nmi_watchdog=1 so that we can see (in -Q7)
what happens on the other CPUs during such long delays.
> I also looked briefly at find_first_bit since it appears in a number
> of traces. Just curious, but the coding for the i386 version is MUCH
> different in style than several other architectures (e.g, PPC64,
> SPARC). Is there some reason why it is recursive on the x86 and a loop
> in the others?
what do you mean by recursive? It uses the SCAS (scan string) x86
instruction.
Ingo
next prev parent reply other threads:[~2004-09-02 5:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-01 22:56 [patch] voluntary-preempt-2.6.9-rc1-bk4-Q7 Mark_H_Johnson
2004-09-02 5:34 ` Ingo Molnar [this message]
[not found] <OF3E3C1690.FD6E285E-ON86256F03.004CDD15-86256F03.004CDD4F@raytheon.com>
2004-09-02 14:43 ` Ingo Molnar
-- strict thread matches above, loose matches on Subject: below --
2004-09-02 13:33 Mark_H_Johnson
2004-09-02 13:18 Mark_H_Johnson
2004-09-02 13:37 ` Ingo Molnar
2004-09-02 18:01 ` Lee Revell
2004-08-28 20:10 [patch] voluntary-preempt-2.6.9-rc1-bk4-Q2 Daniel Schmitt
2004-08-28 20:31 ` [patch] voluntary-preempt-2.6.9-rc1-bk4-Q3 Ingo Molnar
2004-08-28 21:10 ` Lee Revell
2004-08-28 21:13 ` Ingo Molnar
2004-08-28 21:16 ` Lee Revell
2004-08-28 23:51 ` Lee Revell
2004-08-29 2:35 ` Lee Revell
2004-08-29 5:43 ` [patch] voluntary-preempt-2.6.9-rc1-bk4-Q4 Ingo Molnar
2004-08-30 9:06 ` [patch] voluntary-preempt-2.6.9-rc1-bk4-Q5 Ingo Molnar
2004-09-01 8:29 ` [patch] voluntary-preempt-2.6.9-rc1-bk4-Q6 Ingo Molnar
2004-09-01 13:51 ` [patch] voluntary-preempt-2.6.9-rc1-bk4-Q7 Ingo Molnar
2004-09-01 17:09 ` Thomas Charbonnel
2004-09-01 19:03 ` K.R. Foley
2004-09-01 20:11 ` Peter Zijlstra
2004-09-01 20:16 ` Lee Revell
2004-09-01 20:53 ` K.R. Foley
[not found] ` <41367E5D.3040605@cybsft.com>
2004-09-02 5:37 ` Ingo Molnar
2004-09-02 5:40 ` Ingo Molnar
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