From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f176.google.com (mail-lb0-f176.google.com [209.85.217.176]) by kanga.kvack.org (Postfix) with ESMTP id D746B82905 for ; Wed, 11 Mar 2015 16:03:40 -0400 (EDT) Received: by lbvn10 with SMTP id n10so11372924lbv.11 for ; Wed, 11 Mar 2015 13:03:39 -0700 (PDT) Received: from mail-la0-x22f.google.com (mail-la0-x22f.google.com. [2a00:1450:4010:c03::22f]) by mx.google.com with ESMTPS id f7si3057752lab.19.2015.03.11.13.03.38 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 Mar 2015 13:03:38 -0700 (PDT) Received: by labgd6 with SMTP id gd6so11274279lab.6 for ; Wed, 11 Mar 2015 13:03:38 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <5500932F.6030107@suse.cz> References: <1424958666-18241-1-git-send-email-vbabka@suse.cz> <1424958666-18241-3-git-send-email-vbabka@suse.cz> <5500932F.6030107@suse.cz> Date: Wed, 11 Mar 2015 23:03:37 +0300 Message-ID: Subject: Re: [PATCH 2/4] mm, procfs: account for shmem swap in /proc/pid/smaps From: Konstantin Khlebnikov Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: "linux-mm@kvack.org" , Jerome Marchand , Linux Kernel Mailing List , Andrew Morton , linux-doc@vger.kernel.org, Hugh Dickins , Michal Hocko , "Kirill A. Shutemov" , Cyrill Gorcunov , Randy Dunlap , linux-s390@vger.kernel.org, Martin Schwidefsky , Heiko Carstens , Peter Zijlstra , Paul Mackerras , Arnaldo Carvalho de Melo , Oleg Nesterov On Wed, Mar 11, 2015 at 10:10 PM, Vlastimil Babka wrote: > On 03/11/2015 01:30 PM, Konstantin Khlebnikov wrote: >> >> On Thu, Feb 26, 2015 at 4:51 PM, Vlastimil Babka wrote: >>> >>> Currently, /proc/pid/smaps will always show "Swap: 0 kB" for shmem-backed >>> mappings, even if the mapped portion does contain pages that were swapped >>> out. >>> This is because unlike private anonymous mappings, shmem does not change >>> pte >>> to swap entry, but pte_none when swapping the page out. In the smaps page >>> walk, such page thus looks like it was never faulted in. >> >> >> Maybe just add count of swap entries allocated by mapped shmem into >> swap usage of this vma? That's isn't exactly correct for partially >> mapped shmem but this is something weird anyway. > > > Yeah for next version I want to add a patch optimizing for the (hopefully) > common cases: > > 1. SHMEM_I(inode)->swapped is 0 - no need to consult radix tree > 2. shmem inode is mapped fully (I hope it's ok to just compare its size and > mapping size) - just use the value of SHMEM_I(inode)->swapped like you > suggest > BTW using radix tree iterator you can count swap entries without touching page->count. Also long time ago I've suggested to mark swap entries in shmem with one of radix tree tag -- tagged iterator is much faster for sparse trees. (just for this case it's overkill but these tags can speedup swapoff) -- 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