Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753964Ab3GXSzx (ORCPT ); Wed, 24 Jul 2013 14:55:53 -0400 Received: from relay.parallels.com ([195.214.232.42]:32779 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751579Ab3GXSzv (ORCPT ); Wed, 24 Jul 2013 14:55:51 -0400 Message-ID: <51F0232D.6060306@parallels.com> Date: Wed, 24 Jul 2013 22:55:41 +0400 From: Pavel Emelyanov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Cyrill Gorcunov CC: Andy Lutomirski , James Bottomley , Linux MM , LKML , Andrew Morton , Matt Mackall , Xiao Guangrong , Marcelo Tosatti , KOSAKI Motohiro , Stephen Rothwell Subject: Re: [PATCH] mm: Save soft-dirty bits on swapped pages References: <20130724160826.GD24851@moon> <20130724163734.GE24851@moon> <20130724171728.GH8508@moon> <1374687373.7382.22.camel@dabdike> <20130724181516.GI8508@moon> <20130724185256.GA24365@moon> In-Reply-To: <20130724185256.GA24365@moon> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [89.169.95.100] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1751 Lines: 42 On 07/24/2013 10:52 PM, Cyrill Gorcunov wrote: > On Wed, Jul 24, 2013 at 11:21:46AM -0700, Andy Lutomirski wrote: >>> >>> I fear for tracking soft-dirty-bit for swapped entries we sinply have >>> no other place than pte (still i'm quite open for ideas, maybe there >>> are a better way which I've missed). >> >> I know approximately nothing about how swap and anon_vma work. >> >> For files, sticking it in struct page seems potentially nicer, >> although finding a free bit might be tough. (FWIW, I have plans to >> free up a page flag on x86 some time moderately soon as part of a >> completely unrelated project.) I think this stuff really belongs to >> the address_space more than it belongs to the pte. > > Well, some part of information already lays in pte (such as 'file' bit, > swap entries) so it looks natural i think to work on this level. but > letme think if use page struct for that be more convenient... It hardly will be. Consider we have a page shared between two tasks, then first one "touches" it and soft-dirty is put onto his PTE and, subsequently, the page itself. The we go and clear sofr-dirty for the 2nd task. What should we do with the soft-dirty bit on the page? The soft-dirty thing watches changes in the virtual memory, not in the physical one. >> >> How do you handle the write syscall? > > I fear I somehow miss your point here, could please alaborate a bit? > There is no additional code I know of being write() specific, just > a code for #PF exceptions. > . > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/