From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx181.postini.com [74.125.245.181]) by kanga.kvack.org (Postfix) with SMTP id 253F16B0068 for ; Thu, 1 Nov 2012 22:26:18 -0400 (EDT) Date: Fri, 2 Nov 2012 11:32:20 +0900 From: Minchan Kim Subject: Re: [RFC] Support volatile range for anon vma Message-ID: <20121102023220.GA3326@bbox> References: <1351133820-14096-1-git-send-email-minchan@kernel.org> <0000013a9881a86c-c0fb5823-b6e7-4bea-8707-f6b8eddae14d-000000@email.amazonses.com> <20121026005851.GD15767@bbox> <0000013abda6fc7d-6cfbef1e-bc7d-4f4f-bb38-221729e8c9f9-000000@email.amazonses.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0000013abda6fc7d-6cfbef1e-bc7d-4f4f-bb38-221729e8c9f9-000000@email.amazonses.com> Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, John Stultz , Andrew Morton , Android Kernel Team , Robert Love , Mel Gorman , Hugh Dickins , Dave Hansen , Rik van Riel , Dave Chinner , Neil Brown , Mike Hommey , Taras Glek , KOSAKI Motohiro , KAMEZAWA Hiroyuki Hi Christoph, On Thu, Nov 01, 2012 at 08:26:09PM +0000, Christoph Lameter wrote: > On Fri, 26 Oct 2012, Minchan Kim wrote: > > > I guess it would improve system performance very well. > > But as I wrote down in description, downside of the patch is that we have to > > age anon lru although we don't have swap. But gain via the patch is bigger than > > loss via aging of anon lru when memory pressure happens. I don't see other downside > > other than it. What do you think about it? > > (I didn't implement anon lru aging in case of no-swap but it's trivial > > once we decide) > > > I am a bit confused like some of the others as to why this patch is > necessary since we already have DONT_NEED. Totally, my fault. I should have written clearly. DONT_NEED have to zap all pte entries/tlb flush when system call happens so DONT_NEED isn't cheap. Even, later if user accesses address again, page fault happens. This patch is to remove above two overheads. while I discussed with KOSAKI, I found there was trial of simillar goal by Rik. https://lkml.org/lkml/2007/4/17/53 But as I look over the code, it seems to have a cost about setting PG_lazyfree on all pages of range which isn't in my implementation. Anyway, I would like to know where Rik's patch wasn't merged at that time. > > -- > 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 -- Kind regards, Minchan Kim -- 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