From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 527406B01E3 for ; Mon, 12 Apr 2010 10:51:08 -0400 (EDT) Message-ID: <4BC33314.4090809@redhat.com> Date: Mon, 12 Apr 2010 17:49:56 +0300 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [PATCH 00 of 41] Transparent Hugepage Support #17 References: <20100405232115.GM5825@random.random> <20100406011345.GT5825@random.random> <20100406090813.GA14098@elte.hu> <20100410184750.GJ5708@random.random> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Andrea Arcangeli , Ingo Molnar , 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 , Chris Wright , bpicco@redhat.com, KOSAKI Motohiro , Balbir Singh , Arnd Bergmann , "Michael S. Tsirkin" , Peter Zijlstra , Johannes Weiner , Daisuke Nishimura List-ID: On 04/12/2010 05:24 PM, Christoph Lameter wrote: > >> To me what is relevant is that everyone in the VM camp seems to want >> transparent hugepages in some shape or form, because of the about >> linear speedup they provide to everything running on them on bare >> metal (and an more than linear cumulative speedup in case of nested >> pagetables for obvious reasons), no matter what design that it is. >> > We want huge pages yes. But transparent? If you can define transparent > then we may agree at some point. Certainly not transparent in the sense of > volatile objects that suddenly convert from 2M to 4K sizes causing > breakage. > Suddenly converting from 2M to 4k is a requirement, otherwise we could just use hugetlbfs. It's simple, we want huge pages when we have the memory and small pages when we don't. Only the kernel knows about memory pressure, so it's up to the kernel to break apart and put together those huge pages. If you have other requirements, they have to come on top, not replace our requirements. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain. -- 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