Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756366AbZCZAdj (ORCPT ); Wed, 25 Mar 2009 20:33:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754077AbZCZAda (ORCPT ); Wed, 25 Mar 2009 20:33:30 -0400 Received: from mx2.redhat.com ([66.187.237.31]:54155 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752970AbZCZAd3 (ORCPT ); Wed, 25 Mar 2009 20:33:29 -0400 Message-ID: <49CACD0B.4060901@redhat.com> Date: Wed, 25 Mar 2009 20:32:11 -0400 From: Ric Wheeler User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Bron Gondwana CC: Linus Torvalds , Theodore Tso , David Rees , Jesper Krogh , Linux Kernel Mailing List Subject: Re: Linux 2.6.29 References: <49C87B87.4020108@krogh.cc> <72dbd3150903232346g5af126d7sb5ad4949a7b5041f@mail.gmail.com> <49C88C80.5010803@krogh.cc> <72dbd3150903241200v38720ca0x392c381f295bdea@mail.gmail.com> <20090325183011.GN32307@mit.edu> <20090325220530.GR32307@mit.edu> <20090325234604.GA14828@brong.net> In-Reply-To: <20090325234604.GA14828@brong.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1239 Lines: 34 Bron Gondwana wrote: > On Wed, Mar 25, 2009 at 04:23:08PM -0700, Linus Torvalds wrote: > >> On Wed, 25 Mar 2009, Theodore Tso wrote: >> >>>> The problem being that unlike the ratio, there's no sane default value >>>> that you can at least argue is not _entirely_ pointless. >>>> >>> Well, if the maximum time that someone wants to wait for an fsync() to >>> return is one second, and the RAID array can write 100MB/sec >>> >> How are you going to tell the kernel that the RAID array can write >> 100MB/s? >> >> The kernel has no idea. >> > > Not at boot up, but after it's been using the RAID array for a little > while it could... > > Bron (... imagining a tunable "max_fsync_wait_target_centisecs = 100" > which caused the kernel to notice how long flushes were taking > and tune its buffer sizes to be approximately right over time ) > This tuning logic is the core of what Josef Bacik did for the transaction batching code for ext4.... ric -- 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/