Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 28 Dec 2001 12:30:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 28 Dec 2001 12:30:11 -0500 Received: from mail.xmailserver.org ([208.129.208.52]:35853 "EHLO mail.xmailserver.org") by vger.kernel.org with ESMTP id ; Fri, 28 Dec 2001 12:30:04 -0500 Date: Fri, 28 Dec 2001 09:33:48 -0800 (PST) From: Davide Libenzi X-X-Sender: davide@blue1.dev.mcafeelabs.com To: Alan Cox cc: "Jeffrey W. Baker" , lkml Subject: Re: 2.4.17 absurd number of context switches In-Reply-To: Message-ID: 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 On Fri, 28 Dec 2001, Alan Cox wrote: > > > The scheduler is _good_ at the three process case. Run some straces it looks > > > more like postgres is doing wacky yield based locks. > > > > The scheduler that Linus merged in 2.5.2-pre3 will solve the problem. > > Looking at the postgres traces here it wont make any difference at all. Not > one iota. If I am reading it right I have processes each going > yield, yield, yield... so the kernel does just that (and indeed posix > semantics require that behaviour). task A old the lock , counter = 2 task B counter = 5 and task C counter = 4 are woke up try to look at a switch dump. the scheduler will spend 3 entire time slices switching between B and C before A will get back the CPU and will free the lock. - Davide - 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/