From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 741DC6B01E3 for ; Mon, 12 Apr 2010 09:32:43 -0400 (EDT) Date: Mon, 12 Apr 2010 15:30:19 +0200 From: Andrea Arcangeli Subject: Re: hugepages will matter more in the future Message-ID: <20100412133019.GZ5656@random.random> References: <4BC0E2C4.8090101@redhat.com> <4BC0E556.30304@redhat.com> <4BC19663.8080001@redhat.com> <4BC19916.20100@redhat.com> <20100411110015.GA10149@elte.hu> <4BC1B034.4050302@redhat.com> <20100411115229.GB10952@elte.hu> <20100412042230.5d974e5d@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100412042230.5d974e5d@infradead.org> Sender: owner-linux-mm@kvack.org To: Arjan van de Ven Cc: Ingo Molnar , Avi Kivity , Jason Garrett-Glaser , Mike Galbraith , Linus Torvalds , Pekka Enberg , Andrew Morton , linux-mm@kvack.org, Marcelo Tosatti , Adam Litke , Izik Eidus , Hugh Dickins , Nick Piggin , Rik van Riel , Mel Gorman , Dave Hansen , Benjamin Herrenschmidt , Mike Travis , KAMEZAWA Hiroyuki , Christoph Lameter , Chris Wright , bpicco@redhat.com, KOSAKI Motohiro , Balbir Singh , Arnd Bergmann , "Michael S. Tsirkin" , Peter Zijlstra , Johannes Weiner , Daisuke Nishimura List-ID: On Mon, Apr 12, 2010 at 04:22:30AM -0700, Arjan van de Ven wrote: > Now hugepages have some interesting other advantages, namely they save > pagetable memory..which for something like TPC-C on a fork based > database can be a measureable win. It doesn't save pagetable memory (as in `grep MemFree /proc/meminfo`). To achive that we'd need to return -ENOMEM from split_huge_page_pmd and split_huge_page, which would complicate things significantly. I'd prefer if we could get rid gradually of split_huge_page_pmd calls instead of having to handle a retval in several inner nested functions that don't contemplate returning error like all their callers. I think the saving in pagetables isn't really interesting... it's a couple of gigabytes but it doesn't move the needle as much as being able to boost CPU performance. -- 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