From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753503AbZBCD6S (ORCPT ); Mon, 2 Feb 2009 22:58:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751668AbZBCD6G (ORCPT ); Mon, 2 Feb 2009 22:58:06 -0500 Received: from turing-police.cc.vt.edu ([128.173.14.107]:34359 "EHLO turing-police.cc.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751577AbZBCD6F (ORCPT ); Mon, 2 Feb 2009 22:58:05 -0500 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.2 To: Thomas Pilarski Cc: Mike Galbraith , Peter Zijlstra , Andrew Morton , Gregory Haskins , 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 In-Reply-To: Your message of "Mon, 02 Feb 2009 08:43:55 +0100." <1233560635.4126.18.camel@localhost.localdomain> From: Valdis.Kletnieks@vt.edu References: <20090128125604.94ed3fe0.akpm@linux-foundation.org> <1233181507.6988.14.camel@bugs-laptop> <1233220048.7835.19.camel@twins> <1233223979.5294.41.camel@bugs-laptop> <1233224644.5294.52.camel@bugs-laptop> <1233229028.4495.34.camel@laptop> <1233237934.11129.183.camel@bugs-laptop> <1233302270.6061.9.camel@marge.simson.net> <1233560635.4126.18.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1233633409_15229P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Mon, 02 Feb 2009 22:56:49 -0500 Message-ID: <51126.1233633409@turing-police.cc.vt.edu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --==_Exmh_1233633409_15229P Content-Type: text/plain; charset=us-ascii On Mon, 02 Feb 2009 08:43:55 +0100, Thomas Pilarski said: > 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. Am I the only one that's scared by the concept of anything that beats on random numbers enough to need 5 million of them a second, but is still using the relatively sucky one that's in most glibc's? :) --==_Exmh_1233633409_15229P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFJh8CBcC3lWbTT17ARAr6hAKCQJHMNavoaHrU2VP7h/wBvmiQ1gwCfbCon vux39H6Al4XRlWu3etGBPKY= =G8RB -----END PGP SIGNATURE----- --==_Exmh_1233633409_15229P--