From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753077AbZBBHre (ORCPT ); Mon, 2 Feb 2009 02:47:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750874AbZBBHrZ (ORCPT ); Mon, 2 Feb 2009 02:47:25 -0500 Received: from mail-in-14.arcor-online.net ([151.189.21.54]:60080 "EHLO mail-in-14.arcor-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750698AbZBBHrY (ORCPT ); Mon, 2 Feb 2009 02:47:24 -0500 X-DKIM: Sendmail DKIM Filter v2.6.0 mail-in-01.arcor-online.net 867CD3326DD Subject: Re: [Bugme-new] [Bug 12562] New: High overhead while switching or synchronizing threads on different cores From: Thomas Pilarski To: Mike Galbraith Cc: Peter Zijlstra , Andrew Morton , Gregory Haskins , bugme-daemon@bugzilla.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <1233302270.6061.9.camel@marge.simson.net> 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> Content-Type: text/plain Date: Mon, 02 Feb 2009 08:43:55 +0100 Message-Id: <1233560635.4126.18.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.24.3 (2.24.3-1.fc10) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.