From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: Re: [00/41] Large Blocksize Support V7 (adds memmap support) Date: Tue, 18 Sep 2007 21:18:53 +0200 Message-ID: <20070918191853.GB7541@v2.random> References: <20070911060349.993975297@sgi.com> <200709161853.12050.nickpiggin@yahoo.com.au> <200709181116.22573.nickpiggin@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Nick Piggin , Christoph Lameter , Mel Gorman , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Christoph Hellwig , William Lee Irwin III , David Chinner , Jens Axboe , Badari Pulavarty , Maxim Levitsky , Fengguang Wu , swin wang , totty.lu@gmail.com, hugh@veritas.com, joern@lazybastard.org To: Linus Torvalds Return-path: Received: from ns.suse.de ([195.135.220.2]:42076 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758315AbXIRTS4 (ORCPT ); Tue, 18 Sep 2007 15:18:56 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, Sep 18, 2007 at 11:30:17AM -0700, Linus Torvalds wrote: > The fact is, *none* of those things are true. The VM doesn't guarantee > anything, and is already very much about statistics in many places. You Many? I can't recall anything besides PF_MEMALLOC and the decision that the VM is oom. Those are the only two gray areas... the safety margin is large enough that nobody notices the lack of black-and-white solution. So instead of working to provide guarantees for the above two gray spots, we're making everything weaker, that's the wrong direction as far as I can tell, especially if we're going to mess up big time the commo code in a backwards way only for those few users of those few I/O devices out there. In general every time reliability has a low priority than performance I've an hard time to enjoy it.