From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753226Ab0CXIzQ (ORCPT ); Wed, 24 Mar 2010 04:55:16 -0400 Received: from relay2.sgi.com ([192.48.179.30]:42937 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751471Ab0CXIzN (ORCPT ); Wed, 24 Mar 2010 04:55:13 -0400 Date: Wed, 24 Mar 2010 03:55:11 -0500 From: Robin Holt To: Andi Kleen Cc: holt@sgi.com, Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , Venkatesh Pallipadi , Suresh Siddha , Linux Kernel Mailing List , x86@kernel.org, Rafael Wysocki Subject: Re: [patch 0/2] x86,pat: Reduce contention on the memtype_lock -V4 Message-ID: <20100324085511.GJ4920@sgi.com> References: <20100324003608.811051277@gulag1.americas.sgi.com> <87wrx2for5.fsf@basil.nowhere.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87wrx2for5.fsf@basil.nowhere.org> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 24, 2010 at 03:16:14AM +0100, Andi Kleen wrote: > holt@sgi.com writes: > > > Tracking memtype on x86 uses a single global spin_lock for either reading > > or changing the memory type. This includes changes made to page flags > > which is perfectly parallel. > > > > Part one of the patchset makes the page-based tracking use cmpxchg > > without a need for a lock. > > > > Part two of the patchset converts the spin_lock into a read/write lock. > > I'm curious: in what workloads did you see contention? > > For any scalability patches it would be always good to have a description > of the workload. It was a job using xpmem (an out of tree kernel module) which uses vm_insert_pfn to establish ptes. The scalability issues were shown in the first patch. I do not have any test which shows a performance difference with the spin_lock to rw_lock conversion. Robin