From owner-freebsd-performance@FreeBSD.ORG Wed Mar 24 10:40:55 2004 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DB3E416A4CF for ; Wed, 24 Mar 2004 10:40:55 -0800 (PST) Received: from tx0.oucs.ox.ac.uk (tx0.oucs.ox.ac.uk [129.67.1.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3A69443D31 for ; Wed, 24 Mar 2004 10:40:55 -0800 (PST) (envelope-from colin.percival@wadham.ox.ac.uk) Received: from scan0.oucs.ox.ac.uk ([129.67.1.162] helo=localhost) by tx0.oucs.ox.ac.uk with esmtp (Exim 4.24) id 1B6DJ8-0007v1-Di for performance@freebsd.org; Wed, 24 Mar 2004 18:40:54 +0000 Received: from rx0.oucs.ox.ac.uk ([129.67.1.161]) by localhost (scan0.oucs.ox.ac.uk [129.67.1.162]) (amavisd-new, port 25) with ESMTP id 30417-01 for ; Wed, 24 Mar 2004 18:40:54 +0000 (GMT) Received: from gateway.wadham.ox.ac.uk ([163.1.161.253]) by rx0.oucs.ox.ac.uk with smtp (Exim 4.24) id 1B6DJ8-0007uv-09 for performance@freebsd.org; Wed, 24 Mar 2004 18:40:54 +0000 Received: (qmail 18058 invoked by uid 1004); 24 Mar 2004 18:40:53 -0000 Received: from colin.percival@wadham.ox.ac.uk by gateway by uid 71 with qmail-scanner-1.20 (clamscan: 0.67. sweep: 2.18/3.79. Clear:RC:1(163.1.161.131):. Processed in 0.081856 secs); 24 Mar 2004 18:40:53 -0000 Received: from dhcp1131.wadham.ox.ac.uk (HELO piii600.wadham.ox.ac.uk) (163.1.161.131) by gateway.wadham.ox.ac.uk with SMTP; 24 Mar 2004 18:40:53 -0000 Message-Id: <6.0.1.1.1.20040324183111.043c2228@imap.sfu.ca> X-Sender: cperciva@imap.sfu.ca (Unverified) X-Mailer: QUALCOMM Windows Eudora Version 6.0.1.1 Date: Wed, 24 Mar 2004 18:40:51 +0000 To: Sean Chittenden From: Colin Percival In-Reply-To: References: <200403170937.i2H9bDvO033177@repoman.freebsd.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Mailman-Approved-At: Wed, 24 Mar 2004 12:06:43 -0800 cc: performance@freebsd.org cc: Colin Percival cc: Jason Coene Subject: Re: cvs commit: src/sys/kern sysv_sem.c X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 24 Mar 2004 18:40:56 -0000 At 17:51 24/03/2004, Sean Chittenden wrote: >> FreeBSD src repository >> >> Modified files: >> sys/kern sysv_sem.c >> Log: >> Adjust the number of processes waiting on a semaphore properly if we're >> woken up in the middle of sleeping. > >Have you read the thread on performance@ regarding semaphore performance problems for PostgreSQL? Do you think this has any bearing on that problem? -sc I hadn't seen the thread on performance@ until now, but it sounds like this is very likely related -- this bug would result in processes not being woken up when a semaphore becomes free. Jason, could you update your src/sys/kern/sysv_sem.c to the latest revision (1.69), build a new kernel, and see if the problem goes away? Colin Percival