From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262359AbVAOXiW (ORCPT ); Sat, 15 Jan 2005 18:38:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262364AbVAOXhk (ORCPT ); Sat, 15 Jan 2005 18:37:40 -0500 Received: from mail.joq.us ([67.65.12.105]:57218 "EHLO sulphur.joq.us") by vger.kernel.org with ESMTP id S262363AbVAOXh0 (ORCPT ); Sat, 15 Jan 2005 18:37:26 -0500 To: Ingo Molnar Cc: Chris Wright , Matt Mackall , Paul Davis , Christoph Hellwig , Andrew Morton , Lee Revell , arjanv@redhat.com, alan@lxorguk.ukuu.org.uk, linux-kernel@vger.kernel.org Subject: Re: [PATCH] [request for inclusion] Realtime LSM References: <20050110212019.GG2995@waste.org> <200501111305.j0BD58U2000483@localhost.localdomain> <20050111191701.GT2940@waste.org> <20050111125008.K10567@build.pdx.osdl.net> <20050111205809.GB21308@elte.hu> <20050111131400.L10567@build.pdx.osdl.net> <20050111212719.GA23477@elte.hu> <87fz15j325.fsf@sulphur.joq.us> <20050115134922.GA10114@elte.hu> <874qhiwb1q.fsf@sulphur.joq.us> From: "Jack O'Quin" Date: Sat, 15 Jan 2005 17:38:11 -0600 In-Reply-To: <874qhiwb1q.fsf@sulphur.joq.us> (Jack O'Quin's message of "Sat, 15 Jan 2005 17:02:41 -0600") Message-ID: <871xcmuuu4.fsf@sulphur.joq.us> User-Agent: Gnus/5.1006 (Gnus v5.10.6) XEmacs/21.4 (Corporate Culture, linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> * Jack O'Quin wrote: >>> One major problem: this `nice --20' hack affects every thread, not >>> just the critical realtime ones. That's not what we want. Audio >>> applications make very conscious choices which threads run with high >>> priority and which do not. > Ingo Molnar writes: >> how much did this problem affect your test? Could the source of the 500 >> msec delays be the non-highprio components of the test that somehow >> became nice --20? Jack O'Quin writes: > Probably, the best way to tell would be patching JACK so it uses > nice(-20) instead of pthread_setschedparam() for the realtime threads. > As a hack, that looks easy. I'll build a working directory with just > that change, so we can experiment with it better. Bah! Nothing is ever as easy as it looks. According to the manpage, nice(2) is per-process not per-thread. That does not give the granularity we need. Is that correct? If so, I can't think of any way to make this work. Suggestions? We need to allow both realtime and non-realtime threads in the same process. Anything less would require an enormous rewrite for most audio programs, an unreasonable thing to ask. -- joq