Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755573AbXIWG4z (ORCPT ); Sun, 23 Sep 2007 02:56:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752212AbXIWG4q (ORCPT ); Sun, 23 Sep 2007 02:56:46 -0400 Received: from mx1.Informatik.Uni-Tuebingen.De ([134.2.12.5]:45792 "EHLO mx1.informatik.uni-tuebingen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753188AbXIWG4p (ORCPT ); Sun, 23 Sep 2007 02:56:45 -0400 From: Goswin von Brederlow To: Andrea Arcangeli Cc: Goswin von Brederlow , Mel Gorman , Andrew Morton , Joern Engel , Nick Piggin , Christoph Lameter , torvalds@linux-foundation.org, 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 Subject: Re: [00/41] Large Blocksize Support V7 (adds memmap support) References: <20070911060349.993975297@sgi.com> <200709110452.20363.nickpiggin@yahoo.com.au> <20070911121225.GE13132@lazybastard.org> <20070915014449.4f9cdb51.akpm@linux-foundation.org> <87ir6c3z2l.fsf@informatik.uni-tuebingen.de> <20070915155100.GA21861@v2.random> <20070916181504.GB16406@skynet.ie> <20070916185052.GG6708@v2.random> <87lkb643ug.fsf@informatik.uni-tuebingen.de> <20070918193102.GC7541@v2.random> Date: Sun, 23 Sep 2007 08:56:39 +0200 In-Reply-To: <20070918193102.GC7541@v2.random> (Andrea Arcangeli's message of "Tue, 18 Sep 2007 21:31:02 +0200") Message-ID: <87d4w97tug.fsf@informatik.uni-tuebingen.de> User-Agent: Gnus/5.110006 (No Gnus v0.6) XEmacs/21.4.19 (linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1897 Lines: 44 Andrea Arcangeli writes: > On Mon, Sep 17, 2007 at 12:56:07AM +0200, Goswin von Brederlow wrote: >> When has free ever given any usefull "free" number? I can perfectly >> fine allocate another gigabyte of memory despide free saing 25MB. But >> that is because I know that the buffer/cached are not locked in. > > Well, as you said you know that buffer/cached are not locked in. If > /proc/meminfo would be rubbish like you seem to imply in the first > line, why would we ever bother to export that information and even > waste time writing a binary that parse it for admins? As a user I know it because I didn't put a kernel source into /tmp. A programm can't reasonably know that. >> On the other hand 1GB can instantly vanish when I start a xen domain >> and anything relying on the free value would loose. > > Actually you better check meminfo or free before starting a 1G of Xen!! Xen has its own memory pool and can quite agressively reclaim memory from dom0 when needed. I just ment to say that the number in /proc/meminfo can change in a second so it is not much use knowing what it said last minute. >> The only sensible thing for an application concerned with swapping is >> to whatch the swapping and then reduce itself. Not the amount >> free. Although I wish there were some kernel interface to get a >> preasure value of how valuable free pages would be right now. I would >> like that for fuse so a userspace filesystem can do caching without >> cripling the kernel. > > Repeated drop caches + free can help. I would kill any programm that does that to find out how much free ram the system has. MfG Goswin - 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/