From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Brodowski Subject: Performance impact of CONFIG_SCHED_MC? direct-io test case Date: Thu, 5 Aug 2010 22:54:48 +0200 Message-ID: <20100805205448.GB6318@comet.dominikbrodowski.net> References: <20100805123649.GA18672@dhcp231-156.rdu.redhat.com> <20100805113240.GA29846@think> <20100805153519.GA7242@comet.dominikbrodowski.net> <20100805163519.GA6604@comet.dominikbrodowski.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20100805163519.GA6604@comet.dominikbrodowski.net> Sender: linux-raid-owner@vger.kernel.org To: linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org Cc: Chris Mason , josef@redhat.com, Valdis.Kletnieks@vt.edu, Michael Monnerie , Christoph Hellwig , linux-raid@vger.kernel.org, xfs@oss.sgi.com, dm-devel@redhat.com List-Id: linux-raid.ids How large is the performance impact of CONFIG_SCHED_MC -- for which there is a warning that it comes "at a cost of slightly increased overhead in some places."? Well, for the test workload I've been working with lately, dd if= of=/dev/zero bs=8k count=100000 iflag=direct where is a dm-crypted LVM volume consisting of several partitions on a notebook pata harddisk, and all this runs on a Core2 Duo, I get a ~ 10 % performance reduction if CONFIG_SCHED_MC is enabled. Combined with the CONFIG_DEBUG performance reduction mentioned in the other message, all of the reduction from 28 MB/s to 18 MB/s is explained for. Best, Dominik PS: Ingo: you got both mingo@elte.hu and mingo@redhat.com in MAINTAINERS, I suppose both are valid?