Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261320AbVE3KgD (ORCPT ); Mon, 30 May 2005 06:36:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261301AbVE3KgD (ORCPT ); Mon, 30 May 2005 06:36:03 -0400 Received: from mx1.elte.hu ([157.181.1.137]:17085 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S261320AbVE3Kf5 (ORCPT ); Mon, 30 May 2005 06:35:57 -0400 Date: Mon, 30 May 2005 12:33:47 +0200 From: Ingo Molnar To: Andi Kleen Cc: Takashi Iwai , Sven-Thorsten Dietrich , dwalker@mvista.com, bhuey@lnxw.com, nickpiggin@yahoo.com.au, hch@infradead.org, akpm@osdl.org, linux-kernel@vger.kernel.org Subject: Re: RT patch acceptance Message-ID: <20050530103347.GA13425@elte.hu> References: <1117044019.5840.32.camel@sdietrich-xp.vilm.net> <20050526193230.GY86087@muc.de> <20050526200424.GA27162@elte.hu> <20050527123529.GD86087@muc.de> <20050527124837.GA7253@elte.hu> <20050527125630.GE86087@muc.de> <20050527131317.GA11071@elte.hu> <20050527133122.GF86087@muc.de> <20050530095349.GK86087@muc.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050530095349.GK86087@muc.de> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1253 Lines: 32 * Andi Kleen wrote: > > Yes, as Ingo stated many times, addition cond_resched() to > > might_sleep() does achieve the "usable" latencies -- and obviously > > that's hacky. > > But it's the only way to get practial(1)low latency benefit to > everybody - not just a few selected few who know how to set the right > kernel options or do other incarnations and willfully give up > performance and stability. > > It is basically similar to why we often avoid kernel tunables - the > kernel must work well out of the box. > > (1) = not necessarily provable, but good enough at least for jack > et.al. FYI, to get good latencies for jack you currently need the -RT tree and CONFIG_PREEMPT. (see Lee Revell's and Rui Nuno Capela's extensive tests) In other words, cond_resched() in might_sleep() (PREEMPT_VOLUNTARY, which i announced Jul 9 last year) is _not_ good enough for advanced-audio (jack) users. PREEMPT_VOLUNTARY is mostly good enough for simple audio playback / gaming. Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/