From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Thomas Pilarski <thomas.pi@arcor.de>
Cc: Mike Galbraith <efault@gmx.de>,
Andrew Morton <akpm@linux-foundation.org>,
Gregory Haskins <ghaskins@novell.com>,
bugme-daemon@bugzilla.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [Bugme-new] [Bug 12562] New: High overhead while switching or synchronizing threads on different cores
Date: Mon, 02 Feb 2009 09:19:23 +0100 [thread overview]
Message-ID: <1233562763.4787.71.camel@laptop> (raw)
In-Reply-To: <1233560635.4126.18.camel@localhost.localdomain>
On Mon, 2009-02-02 at 08:43 +0100, Thomas Pilarski wrote:
> Am Freitag, den 30.01.2009, 08:57 +0100 schrieb Mike Galbraith:
> > One of those "don't _ever_ do that" things?
>
> I did not known random() uses a system call. It's rather unrealistic to
> have five million system calls in a second. By adding a small loop with
> some calculations near the random, the problem disappears too.
> It is a unlucky chosen data generator.
I suppose you'll have to go bug the glibc people about their random()
implementation.
If you really need random() to perform for your application (monte-carlo
stuff?) You might be better off writing a PRNG with TLS state or
something.
next prev parent reply other threads:[~2009-02-02 8:19 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-12562-10286@http.bugzilla.kernel.org/>
2009-01-28 20:56 ` [Bugme-new] [Bug 12562] New: High overhead while switching or synchronizing threads on different cores Andrew Morton
2009-01-28 22:15 ` Peter Zijlstra
2009-01-28 22:25 ` Thomas Pilarski
2009-01-29 9:07 ` Peter Zijlstra
2009-01-29 10:12 ` Thomas Pilarski
2009-01-29 10:24 ` Thomas Pilarski
2009-01-29 10:31 ` Peter Zijlstra
2009-01-29 11:37 ` Peter Zijlstra
2009-01-29 14:05 ` Thomas Pilarski
2009-01-30 7:57 ` Mike Galbraith
2009-02-02 7:43 ` Thomas Pilarski
2009-02-02 8:19 ` Peter Zijlstra [this message]
2009-02-02 8:33 ` Thomas Pilarski
2009-02-02 8:52 ` Mike Galbraith
2009-02-02 8:55 ` Peter Zijlstra
2009-02-02 12:15 ` Peter Zijlstra
2009-02-02 18:29 ` Michael Kerrisk
2009-02-02 18:35 ` Peter Zijlstra
2009-02-03 4:55 ` Mike Galbraith
2009-02-03 3:56 ` Valdis.Kletnieks
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