From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 26 Sep 2001 12:51:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 26 Sep 2001 12:51:08 -0400 Received: from zok.sgi.com ([204.94.215.101]:7862 "EHLO zok.sgi.com") by vger.kernel.org with ESMTP id ; Wed, 26 Sep 2001 12:51:03 -0400 Message-ID: <00ad01c146ab$9d4b6340$6501a8c0@pchawkes> From: "John Hawkes" To: "Andrew Morton" , Cc: , , , "Andrea Arcangeli" , , , In-Reply-To: <20010926103424.A8893@in.ibm.com> <3BB16834.4393EEA3@zip.com.au> Subject: Re: Locking comment on shrink_caches() Date: Wed, 26 Sep 2001 09:52:12 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: "Andrew Morton" > > John Hawkes from SGI had published some AIM7 numbers that showed > > pagecache_lock to be a bottleneck above 4 processors. At 32 processors, > > half the CPU cycles were spent on waiting for pagecache_lock. The > > thread is at - > > > > http://marc.theaimsgroup.com/?l=lse-tech&m=98459051027582&w=2 > > > > That's NUMA hardware. The per-hashqueue locking change made > a big improvement on that hardware. But when it was used on > Intel hardware it made no measurable difference at all. More specifically, that was on SGI Origin2000 32p mips64 ccNUMA hardware. The pagecache_lock bottleneck is substantially less on SGI Itanium ccNUMA hardware running those AIM7 workloads. I'm seeing moderately significant contention on the Big Kernel Lock, mostly from sys_lseek() and ext2_get_block(). John Hawkes hawkes@sgi.com