Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759323AbZC0APB (ORCPT ); Thu, 26 Mar 2009 20:15:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762655AbZC0AOi (ORCPT ); Thu, 26 Mar 2009 20:14:38 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:38154 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761711AbZC0AOh (ORCPT ); Thu, 26 Mar 2009 20:14:37 -0400 Date: Thu, 26 Mar 2009 17:11:48 -0700 From: Andrew Morton To: Linus Torvalds Cc: Theodore Tso , David Rees , Jesper Krogh , Linux Kernel Mailing List Subject: Re: Linux 2.6.29 Message-Id: <20090326171148.9bf8f1ec.akpm@linux-foundation.org> In-Reply-To: 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> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1232 Lines: 32 On Wed, 25 Mar 2009 16:23:08 -0700 (PDT) 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. > userspace can do it quite easily. Run a self-tuning script after installation and when the disk hardware changes significantly. It is very disappointing that nobody appears to have attempted to do _any_ sensible tuning of these controls in all this time - we just keep thrashing around trying to pick better magic numbers in the base kernel. Maybe we should set the tunables to 99.9% to make it suck enough to motivate someone. -- 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/