From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 4768C6B016A for ; Fri, 2 Sep 2011 01:09:57 -0400 (EDT) Received: by iagv1 with SMTP id v1so3624980iag.14 for ; Thu, 01 Sep 2011 22:09:55 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20110901142027.GI14369@suse.de> References: <282a4531f23c5e35cfddf089f93559130b4bb660.1321112552.git.minchan.kim@gmail.com> <20110901142027.GI14369@suse.de> Date: Fri, 2 Sep 2011 14:09:55 +0900 Message-ID: Subject: Re: [PATCH 3/3] compaction accouting fix From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Andrew Morton , linux-mm , LKML , Johannes Weiner , Rik van Riel On Thu, Sep 1, 2011 at 11:20 PM, Mel Gorman wrote: > On Sun, Nov 13, 2011 at 01:37:43AM +0900, Minchan Kim wrote: >> I saw the following accouting of compaction during test of the series. > > s/accouting/accounting/ both here and in the subject. A nicer name the > patch would have been > > "mm: compaction: Only update compact_blocks_moved if compaction was successful" Thanks, I will fix it at next version. :) > >> >> compact_blocks_moved 251 >> compact_pages_moved 44 >> >> It's very awkward to me although it's possbile because it means we try to compact 251 blocks >> but it just migrated 44 pages. As further investigation, I found isolate_migratepages doesn't >> isolate any pages but it returns ISOLATE_SUCCESS and then, it just increases compact_blocks_moved >> but doesn't increased compact_pages_moved. >> >> This patch makes accouting of compaction works only in case of success of isolation. >> > > compact_blocks_moved exists to indicate the rate compaction is > scanning pageblocks. If compact_blocks_moved and compact_pages_moved > are increasing at a similar rate for example, it could imply that > compaction is doing a lot of scanning but is not necessarily useful > work. It's not necessarily reflected by compact_fail because that > counter is only updated for pages that were isolated from the LRU. You seem to say "compact_pagemigrate_failed" not "compact_fail". > > I now recognise of course that "compact_blocks_moved" was an *awful* > choice of name for this stat. I hope changing stat names as follows unless it's too late(ie, it doesn't break ABI with any tools) compact_blocks_moved -> compact_blocks compact_pages_moved -> compact_pgmigrated_success compact_pagemigrate_failed -> compact_pgmigrated_fail compact_stall -> compact_alloc_stall compact_fail -> compact_alloc_fail compact_success -> compact_alloc_success > > -- > Mel Gorman > SUSE Labs > -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org