Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965457AbXBRAjk (ORCPT ); Sat, 17 Feb 2007 19:39:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965464AbXBRAjk (ORCPT ); Sat, 17 Feb 2007 19:39:40 -0500 Received: from mail02.syd.optusnet.com.au ([211.29.132.183]:54032 "EHLO mail02.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965457AbXBRAjj (ORCPT ); Sat, 17 Feb 2007 19:39:39 -0500 References: <200702162110.03355.kernel@kolivas.org> <200702171417.28376.kernel@kolivas.org> <45D74D34.5020201@redhat.com> <200702180800.07393.kernel@kolivas.org> <20070217154746.7ff10870.akpm@linux-foundation.org> Message-ID: X-Mailer: http://www.courier-mta.org/cone/ From: Con Kolivas To: Andrew Morton Cc: Chuck Ebbert , michael chang , ck mailing list , linux kernel mailing list Subject: Re: 2.6.20-ck1 Date: Sun, 18 Feb 2007 11:39:19 +1100 Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset="US-ASCII" Content-Disposition: inline Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1746 Lines: 50 Andrew Morton writes: > On Sun, 18 Feb 2007 08:00:06 +1100 Con Kolivas wrote: > >> On Sunday 18 February 2007 05:45, Chuck Ebbert wrote: >> ... >> > But the one I like, mm-filesize_dependant_lru_cache_add.patch, >> > has an on-off switch. >> > >> >> ... >> >> Do you still want this patch for mainline?... > > Don't think so. The problems I see are: > > - It's a system-wide knob. In many situations this will do the wrong > thing. Controlling pagecache should be per-process. > > - Its heuristics for working out when to invalidate the pagecache will be > too much for some situations and too little for others. > > - Whatever we do, there will be some applications in some situations > which are hurt badly by changes like this: they'll do heaps of extra IO. > > > Generally, the penalties for getting this stuff wrong are very very high: > orders of magnitude slowdowns in the right situations. Which I suspect > will make any system-wide knob ultimately unsuccessful. Rest assured I wasn't interested in pushing this patch for mainline anyway. -ck users can also rest assured about this patch for the following reasons: - The usage pattern on a desktop will guarantee that this patch helps 99.9% of the time rather than hurts. Therefore, this feature is enabled by default on -ck. - With the usage pattern on a server of any sort, it will be unknown whether this patch helps or harms. Therefore, this feature is disabled by default on -cks. -- -ck - 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/