From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx159.postini.com [74.125.245.159]) by kanga.kvack.org (Postfix) with SMTP id 87FF66B0034 for ; Thu, 25 Jul 2013 12:02:54 -0400 (EDT) Received: by mail-vb0-f48.google.com with SMTP id w15so556230vbf.35 for ; Thu, 25 Jul 2013 09:02:53 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <51F0D3CA.3080902@parallels.com> References: <20130724163734.GE24851@moon> <20130724171728.GH8508@moon> <1374687373.7382.22.camel@dabdike> <20130724181516.GI8508@moon> <20130724185256.GA24365@moon> <51F0232D.6060306@parallels.com> <20130724190453.GJ8508@moon> <51F0D3CA.3080902@parallels.com> From: Andy Lutomirski Date: Thu, 25 Jul 2013 09:02:32 -0700 Message-ID: Subject: Re: [PATCH] mm: Save soft-dirty bits on swapped pages Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Pavel Emelyanov Cc: Cyrill Gorcunov , James Bottomley , Linux MM , LKML , Andrew Morton , Matt Mackall , Xiao Guangrong , Marcelo Tosatti , KOSAKI Motohiro , Stephen Rothwell On Thu, Jul 25, 2013 at 12:29 AM, Pavel Emelyanov wrote: > On 07/24/2013 11:40 PM, Andy Lutomirski wrote: >> On Wed, Jul 24, 2013 at 12:04 PM, Cyrill Gorcunov wrote: >>> On Wed, Jul 24, 2013 at 10:55:41PM +0400, Pavel Emelyanov wrote: >>>>> > >> Perhaps another bit should be allocated to expose to userspace either >> "soft-dirty", "soft-clean", or "soft-dirty unsupported"? >> >> There's another possible issue with private file-backed pages, though: >> how do you distinguish clean-and-not-cowed from cowed-but-soft-clean? >> (The former will reflect changes in the underlying file, I think, but >> the latter won't.) > > There's a bit called PAGE_FILE bit in /proc/pagemap file introduced with > the 052fb0d635df5d49dfc85687d94e1a87bf09378d commit. > > Plz, refer to Documentation/vm/pagemap.txt and soft-dirty.txt, all this > is described there pretty well. > Fair enough. I'm still a little bit concerned that it will be hard for userspace to distinguish between things for which soft-dirty works (which will be more things once the patches are in) and things for which soft-dirty doesn't work, assuming any are left. But maybe this is silly. --Andy -- 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