From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Subject: Re: [RFC] [PATCH 0/5 V2] Huge page backed user-space stacks Date: Thu, 31 Jul 2008 16:04:14 +1000 References: <20080730172317.GA14138@csn.ul.ie> <20080730103407.b110afc2.akpm@linux-foundation.org> In-Reply-To: <20080730103407.b110afc2.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200807311604.14349.nickpiggin@yahoo.com.au> Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Mel Gorman , Eric Munson , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, libhugetlbfs-devel@lists.sourceforge.net List-ID: On Thursday 31 July 2008 03:34, Andrew Morton wrote: > On Wed, 30 Jul 2008 18:23:18 +0100 Mel Gorman wrote: > > On (30/07/08 01:43), Andrew Morton didst pronounce: > > > On Mon, 28 Jul 2008 12:17:10 -0700 Eric Munson wrote: > > > > Certain workloads benefit if their data or text segments are backed > > > > by huge pages. > > > > > > oh. As this is a performance patch, it would be much better if its > > > description contained some performance measurement results! Please. > > > > I ran these patches through STREAM (http://www.cs.virginia.edu/stream/). > > STREAM itself was patched to allocate data from the stack instead of > > statically for the test. They completed without any problem on x86, > > x86_64 and PPC64 and each test showed a performance gain from using > > hugepages. I can post the raw figures but they are not currently in an > > eye-friendly format. Here are some plots of the data though; > > > > x86: > > http://www.csn.ul.ie/~mel/postings/stack-backing-20080730/x86-stream-stac > >k.ps x86_64: > > http://www.csn.ul.ie/~mel/postings/stack-backing-20080730/x86_64-stream-s > >tack.ps ppc64-small: > > http://www.csn.ul.ie/~mel/postings/stack-backing-20080730/ppc64-small-str > >eam-stack.ps ppc64-large: > > http://www.csn.ul.ie/~mel/postings/stack-backing-20080730/ppc64-large-str > >eam-stack.ps > > > > The test was to run STREAM with different array sizes (plotted on X-axis) > > and measure the average throughput (y-axis). In each case, backing the > > stack with large pages with a performance gain. > > So about a 10% speedup on x86 for most STREAM configurations. Handy - > that's somewhat larger than most hugepage-conversions, iirc. Although it might be a bit unusual to have codes doing huge streaming memory operations on stack memory... We can see why IBM is so keen on their hugepages though :) > Do we expect that this change will be replicated in other > memory-intensive apps? (I do). Such as what? It would be nice to see some numbers with some HPC or java or DBMS workload using this. Not that I dispute it will help some cases, but 10% (or 20% for ppc) I guess is getting toward the best case, short of a specifically written TLB thrasher. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org