From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761526AbYBFWCX (ORCPT ); Wed, 6 Feb 2008 17:02:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756277AbYBFWCO (ORCPT ); Wed, 6 Feb 2008 17:02:14 -0500 Received: from terminus.zytor.com ([198.137.202.10]:41627 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755765AbYBFWCN (ORCPT ); Wed, 6 Feb 2008 17:02:13 -0500 Message-ID: <47AA2E40.2020701@zytor.com> Date: Wed, 06 Feb 2008 14:01:36 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Hugh Dickins CC: Tomasz Chmielewski , LKML , Mika Lawando Subject: Re: What is the limit size of tmpfs /dev/shm ? References: <47A9CA0E.3030507@wpkg.org> <47AA0A2E.30701@zytor.com> <47AA102F.1070105@zytor.com> In-Reply-To: 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 Hugh Dickins wrote: > On Wed, 6 Feb 2008, H. Peter Anvin wrote: >> That sounds like a problem in our overall swap handling, not specifically in >> tmpfs. Now, I can't say anything concrete about heavy swap conditions, but in >> light swap conditions I have measured a 20x performance improvement(!) over >> ext3 on real workloads. > > Wow, I'm surprised. I suppose I do jump to thinking of heavy swapping > when light swapping won't be so bad; but even so, 20x ext3 astonishes > me - ext3 wouldn't be anyone's choice for fastest, but even so... > > I certainly guess too much and measure too little: > is there a useful test you could point me to? TIA > The specific application was this: - extract a kernel tarball - "make distclean" - cp -al the resulting tree - apply a patch to each tree - do a diff between the trees - delete all files ... repeat something like 20,000 times. -hpa