From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 30 Mar 2007 05:09:12 +0200 From: Nick Piggin Subject: Re: [rfc][patch 1/2] mm: dont account ZERO_PAGE Message-ID: <20070330030912.GH19407@wotan.suse.de> References: <20070329075805.GA6852@wotan.suse.de> <20070330014633.GA19407@wotan.suse.de> <20070330025936.GA25722@lnx-holt.americas.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070330025936.GA25722@lnx-holt.americas.sgi.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Robin Holt Cc: Hugh Dickins , Andrew Morton , Linus Torvalds , Linux Memory Management List , tee@sgi.com List-ID: On Thu, Mar 29, 2007 at 09:59:37PM -0500, Robin Holt wrote: > On Fri, Mar 30, 2007 at 03:46:34AM +0200, Nick Piggin wrote: > > > Oh, it's easy to devise a test-case of that kind, but does it matter > > > in real life? I admit that what most people run on their 1024-core > > > Altices will be significantly different from what I checked on my > > > laptop back then, but in my case use of the ZERO_PAGE didn't look > > > common enough to make special cases for. > > > > Yeah I don't have access to the box, but it was a constructed test > > of some kind. However this is basically a dead box situation... on > > smaller systems we could still see performance improvements. > > It was not a constructed test. It was an test application which started > up and read one word from each page to fill the page tables (not sure > why that was done), then forked a process for each cpu. At that point, > it was supposed start doing computation using data from an NFS accessible > file. Unfortunately, the file was not found so the application exited > and the machine locked up for hours. Sorry, my mistake. Thanks for the clarification: this sounds like something that will not be helped by per-node ZERO_PAGEs either. So not typical, but something that we'd rather not fall over with. I guess large ranges of zero pages could be quite common in startup of HPC codes operating on large matricies. Thanks, Nick -- 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