From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268396AbUHLBdX (ORCPT ); Wed, 11 Aug 2004 21:33:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268355AbUHLBdW (ORCPT ); Wed, 11 Aug 2004 21:33:22 -0400 Received: from smtp105.mail.sc5.yahoo.com ([66.163.169.225]:34748 "HELO smtp105.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S268350AbUHLB0r (ORCPT ); Wed, 11 Aug 2004 21:26:47 -0400 Message-ID: <411AC750.3040809@yahoo.com.au> Date: Thu, 12 Aug 2004 11:26:40 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.1) Gecko/20040726 Debian/1.7.1-4 X-Accept-Language: en MIME-Version: 1.0 To: gene.heskett@verizon.net CC: linux-kernel@vger.kernel.org, Linus Torvalds , "Udo A. Steinberg" , Andrew Morton , viro@parcelfarce.linux.theplanet.co.uk Subject: Re: Possible dcache BUG References: <200408111037.56062.gene.heskett@verizon.net> In-Reply-To: <200408111037.56062.gene.heskett@verizon.net> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Gene Heskett wrote: >On Wednesday 11 August 2004 01:15, Linus Torvalds wrote: > >>On Tue, 10 Aug 2004, Linus Torvalds wrote: >> >>>So I suspect it's a balancing issue. Possibly just the slight >>>change in slab balancing to fix the highmem problems. Maybe we >>>shrink slab _too_ aggressively or something. >>> >>Udo, that's a simple thing to check. If it's the slab balancing >>changes, then you should be able to test it with just a >> >> bk cset -x1.1830.4.3 >> >>if you have the current BK and are a BK user, or by just revertign >>the patch here ("patch -R -p1" from inside your linux source tree) >>if you're not a BK user.. >> >> Linus >> >> >With the previously attached patch reverted, a fresh kernel builds in: >real 7m18.296s >user 5m49.385s >sys 0m31.760s >which is a marked improvement, but still about 1m30 or so slow. > > This could easily be from too much slab pressure. How much memory do you have? Have you got highmem turned on? The new slab pressure calculation is an improvement in that it won't let slab get out of control and cause OOMs, however it can shrink the slab too much. If you regularly need ZONE_DMA pages, for example. AFAIKS there isn't much you can do about this except go to per-zone slab LRUs. That said, your stability problems should be resolved first. If they are fixed, and you would like to help track down the slowdown, run the kernel compile about 3 times each with and without the patch, and save cat /proc/vmstat before and after each compile. Try to keep all else constant. Thanks Nick