From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753041Ab0DAFt4 (ORCPT ); Thu, 1 Apr 2010 01:49:56 -0400 Received: from mail.gmx.net ([213.165.64.20]:50796 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751209Ab0DAFtt (ORCPT ); Thu, 1 Apr 2010 01:49:49 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX18ogSsrVjwoZdPiGIu99eAZos+ioUMqLuBu8Hd5cT 3uOTPluE774hTp Subject: Re: Issues with Patch: "sched: Improve latencies and throughput" From: Mike Galbraith To: Michael Grzeschik Cc: linux-kernel@vger.kernel.org, rsc@pengutronix.de In-Reply-To: <20100331223106.GJ10342@pengutronix.de> References: <20100331223106.GJ10342@pengutronix.de> Content-Type: text/plain Date: Thu, 01 Apr 2010 07:49:46 +0200 Message-Id: <1270100986.6707.156.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 X-FuHaFi: 0.57999999999999996 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2010-04-01 at 00:31 +0200, Michael Grzeschik wrote: > We are using an arm mx31 embedded cpu with the v2.6.34 Kernelrelease and > realized some issues with the scheduling behaviour the patch "sched: > Improve latencies and throughput" [1] by Mike Galbraith introduced to > the kernel. > > When we used the alsa utility aplay to pipe some audio through an > usbaudio device and put some scheduling overhead on the device, the > amount of underruns, due to the not fast enough refilled ring buffer, > was noticable increased with that patch [1] applied. Until we reverse > applied the patch the amount of underruns was appreciable lower. Testcase? > That in fact is the opposite behaviour to its actual meaning. Not necessarily. NEXT_BUDDY can increase latency for waiters, as can _not_ pulling a waiter to an idle CPU. > [1] 0ec9fab3d186d9cbb00c0f694d4a260d07c198d9 > > mgr -Mike