Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263962AbUIOJzG (ORCPT ); Wed, 15 Sep 2004 05:55:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264098AbUIOJzG (ORCPT ); Wed, 15 Sep 2004 05:55:06 -0400 Received: from mx1.elte.hu ([157.181.1.137]:24520 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S263962AbUIOJzB (ORCPT ); Wed, 15 Sep 2004 05:55:01 -0400 Date: Wed, 15 Sep 2004 11:56:14 +0200 From: Ingo Molnar To: William Lee Irwin III Cc: Lee Revell , Andrea Arcangeli , Nick Piggin , Andrew Morton , linux-kernel Subject: Re: [patch] sched: fix scheduling latencies for !PREEMPT kernels Message-ID: <20040915095614.GB1629@elte.hu> References: <20040914112847.GA2804@elte.hu> <20040914114228.GD2804@elte.hu> <4146EA3E.4010804@yahoo.com.au> <20040914132225.GA9310@elte.hu> <4146F33C.9030504@yahoo.com.au> <20040914140905.GM4180@dualathlon.random> <41470021.1030205@yahoo.com.au> <20040914150316.GN4180@dualathlon.random> <1095210126.2406.70.camel@krustophenia.net> <20040915013925.GF9106@holomorphy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040915013925.GF9106@holomorphy.com> User-Agent: Mutt/1.4.1i 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, autolearn=not spam, 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: 1194 Lines: 29 * William Lee Irwin III wrote: > > With Ingo's patches the worst case latency on the same machine as my XP > > example is about 150 usecs. So, it seems to me that Ingo's patches can > > achieve results as good or better than OSX even without the one or two > > "dangerous" changes, like the removal of lock_kernel around > > do_tty_write. > > The code we're most worried is buggy, not just nonperformant. what code do you mean? The one i know about and which Lee is referring to above is the 6-lines tty unlocking change - the one which Alan objected to rightfully. I've zapped it from my tree. (nobody objected to the original thread on lkml weeks ago where the tty unlocking change was proposed, implemented, alpha-tested and beta-tested in -mm for several releases - that's why it showed up in my 20+ latency-reduction patches.) No latency changes to the tty layer until someone fixes its locking. End of story. 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/