From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932484AbVLAVUp (ORCPT ); Thu, 1 Dec 2005 16:20:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932486AbVLAVUp (ORCPT ); Thu, 1 Dec 2005 16:20:45 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:56006 "EHLO mx3.mail.elte.hu") by vger.kernel.org with ESMTP id S932484AbVLAVUo (ORCPT ); Thu, 1 Dec 2005 16:20:44 -0500 Date: Thu, 1 Dec 2005 22:21:05 +0100 From: Ingo Molnar To: Dinakar Guniguntala Cc: linux-kernel@vger.kernel.org, david singleton Subject: Re: Perf degradation from -rt14 onwards Message-ID: <20051201212105.GA25686@elte.hu> References: <20051201204227.GA16035@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051201204227.GA16035@in.ibm.com> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=AWL autolearn=no SpamAssassin version=3.0.3 0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Dinakar Guniguntala wrote: > I was wondering why the following change was made from -rt14 > onwards. > > > @@ -1634,7 +1531,7 @@ asmlinkage long sys_futex(u32 __user *ua > int val3) > { > struct timespec t; > - unsigned long timeout = MAX_SCHEDULE_TIMEOUT; > + unsigned long timeout = 0; > > This was introduced in patch-2.6.14-rt13-rf3 by David. > > This seems to return spurious -ETIMEDOUT errors even in the non-robust > code and results in userspace (glibc) retrying several mutex > operations before it succeeds. I was chasing down a degradation of > performance of some testcases and was able to fix those by reverting > this change back. nice catch! I've undone this change in my tree. Ingo