Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262568AbTFKR6x (ORCPT ); Wed, 11 Jun 2003 13:58:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262720AbTFKR6x (ORCPT ); Wed, 11 Jun 2003 13:58:53 -0400 Received: from ppp-217-133-42-200.cust-adsl.tiscali.it ([217.133.42.200]:60623 "EHLO dualathlon.random") by vger.kernel.org with ESMTP id S262568AbTFKR6w (ORCPT ); Wed, 11 Jun 2003 13:58:52 -0400 Date: Wed, 11 Jun 2003 20:12:17 +0200 From: Andrea Arcangeli To: Chris Mason Cc: Nick Piggin , Marc-Christian Petersen , Jens Axboe , Marcelo Tosatti , Georg Nikodym , lkml , Matthias Mueller Subject: Re: [PATCH] io stalls (was: -rc7 Re: Linux 2.4.21-rc6) Message-ID: <20030611181217.GX26270@dualathlon.random> References: <200306041246.21636.m.c.p@wolk-project.de> <20030604104825.GR3412@x30.school.suse.de> <3EDDDEBB.4080209@cyberone.com.au> <1055194762.23130.370.camel@tiny.suse.com> <20030611003356.GN26270@dualathlon.random> <1055292839.24111.180.camel@tiny.suse.com> <20030611010628.GO26270@dualathlon.random> <1055296630.23697.195.camel@tiny.suse.com> <20030611021030.GQ26270@dualathlon.random> <1055353360.23697.235.camel@tiny.suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1055353360.23697.235.camel@tiny.suse.com> User-Agent: Mutt/1.4i X-GPG-Key: 1024D/68B9CB43 13D9 8355 295F 4823 7C49 C012 DFA1 686E 68B9 CB43 X-PGP-Key: 1024R/CB4660B9 CC A0 71 81 F4 A0 63 AC C0 4B 81 1D 8C 15 C8 E5 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1172 Lines: 28 On Wed, Jun 11, 2003 at 01:42:41PM -0400, Chris Mason wrote: > + if (q->rq[rw].count >= q->batch_requests) { > + smp_mb(); > + if (waitqueue_active(&q->wait_for_requests[rw])) > + wake_up(&q->wait_for_requests[rw]); in my tree I also changed this to: wake_up_nr(&q->wait_for_requests[rw], q->rq[rw].count); otherwise only one waiter will eat the requests, while multiple waiters can eat requests in parallel instead because we freed not just 1 request but many of them. I wonder if my above change is really the right way to implement the removal of the _exclusive line that went in rc6. However with your patch the wake_up_nr (or ~equivalent removal of _exclusive wakeup of rc6) should mostly improve cpu parallelism in smp and while waiting for I/O, the amount of stuff in the I/O queue and the overall fariness shouldn't change very significantly with this new completely fair FIFO request allocator. Andrea - 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/