Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264687AbTFLCbn (ORCPT ); Wed, 11 Jun 2003 22:31:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264689AbTFLCbn (ORCPT ); Wed, 11 Jun 2003 22:31:43 -0400 Received: from ppp-217-133-42-200.cust-adsl.tiscali.it ([217.133.42.200]:64388 "EHLO dualathlon.random") by vger.kernel.org with ESMTP id S264687AbTFLCbl (ORCPT ); Wed, 11 Jun 2003 22:31:41 -0400 Date: Thu, 12 Jun 2003 04:46:08 +0200 From: Andrea Arcangeli To: Nick Piggin Cc: Chris Mason , Marc-Christian Petersen , Jens Axboe , Marcelo Tosatti , Georg Nikodym , lkml , Matthias Mueller Subject: Re: [PATCH] io stalls Message-ID: <20030612024608.GE1415@dualathlon.random> References: <1055296630.23697.195.camel@tiny.suse.com> <20030611021030.GQ26270@dualathlon.random> <1055353360.23697.235.camel@tiny.suse.com> <20030611181217.GX26270@dualathlon.random> <1055356032.24111.240.camel@tiny.suse.com> <20030611183503.GY26270@dualathlon.random> <3EE7D1AA.30701@cyberone.com.au> <20030612012951.GG1500@dualathlon.random> <1055384547.24111.322.camel@tiny.suse.com> <3EE7E876.80808@cyberone.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3EE7E876.80808@cyberone.com.au> 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: 1752 Lines: 44 On Thu, Jun 12, 2003 at 12:41:58PM +1000, Nick Piggin wrote: > > > Chris Mason wrote: > > >On Wed, 2003-06-11 at 21:29, Andrea Arcangeli wrote: > > > > > >>this will avoid get_request_wait_wakeup to mess the wakeup, so we can > >>wakep_nr(rq.count) safely. > >> > >>then there's the last issue raised by Chris, that is if we get request > >>released faster than the tasks can run, still we can generate a not > >>perfect fairness. My solution to that is to change wake_up to have a > >>nr_exclusive not obeying to the try_to_wakeup retval. that should > >>guarantee exact FIFO then, but it's a minor issue because the requests > >>shouldn't be released systematically in a flood. So I'm leaving it > >>opened for now, the others already addressed should be the major ones. > >> > > > >I think the only time we really need to wakeup more than one waiter is > >when we hit the q->batch_request mark. After that, each new request > >that is freed can be matched with a single waiter, and we know that any > >previously finished requests have probably already been matched to their > >own waiter. > > > > > Nope. Not even then. Each retiring request should submit > a wake up, and the process will submit another request. > So the number of requests will be held at the batch_request > mark until no more waiters. > > Now that begs the question, why have batch_requests anymore? > It no longer does anything. it does nothing w/ _exclusive and w/o the wake_up_nr, that's why I added the wake_up_nr. 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/