Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754744Ab0DOQgP (ORCPT ); Thu, 15 Apr 2010 12:36:15 -0400 Received: from acsinet12.oracle.com ([141.146.126.234]:23871 "EHLO acsinet12.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752801Ab0DOQgN (ORCPT ); Thu, 15 Apr 2010 12:36:13 -0400 Date: Thu, 15 Apr 2010 12:34:55 -0400 From: Chris Mason To: Manfred Spraul Cc: Nick Piggin , zach.brown@oracle.com, jens.axboe@oracle.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] ipc semaphores: reduce ipc_lock contention in semtimedop Message-ID: <20100415163455.GD3794@think> Mail-Followup-To: Chris Mason , Manfred Spraul , Nick Piggin , zach.brown@oracle.com, jens.axboe@oracle.com, linux-kernel@vger.kernel.org References: <1271098163-3663-2-git-send-email-chris.mason@oracle.com> <4BC4A6B2.1090906@colorfullife.com> <20100413173941.GI13327@think> <20100413180945.GD5683@laptop> <20100413181937.GM13327@think> <4BC5EA75.9090803@colorfullife.com> <20100414173319.GA3228@think> <4BC61370.7020700@colorfullife.com> <20100414195003.GE3228@think> <4BC73FC9.1090007@colorfullife.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4BC73FC9.1090007@colorfullife.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-Source-IP: acsmt353.oracle.com [141.146.40.153] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090203.4BC74077.009A:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 711 Lines: 18 On Thu, Apr 15, 2010 at 06:33:13PM +0200, Manfred Spraul wrote: > On 04/14/2010 09:50 PM, Chris Mason wrote: > >On a big system I saw about 4000 semaphores total. The database will > >just allocate as many as it can into a single array and keep creating > >arrays until it has all it needs. > > > What happens if SEMMSL is reduced (first entry in /proc/sys/kernel/sem)? Performance improves slightly but the ipc lock is still at the top of the profile ;) -chris -- 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/