From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx176.postini.com [74.125.245.176]) by kanga.kvack.org (Postfix) with SMTP id 552B16B002B for ; Tue, 6 Nov 2012 12:32:51 -0500 (EST) Message-ID: <50994A58.9000309@redhat.com> Date: Tue, 06 Nov 2012 12:35:20 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH 03/19] mm: compaction: Add scanned and isolated counters for compaction References: <1352193295-26815-1-git-send-email-mgorman@suse.de> <1352193295-26815-4-git-send-email-mgorman@suse.de> In-Reply-To: <1352193295-26815-4-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Peter Zijlstra , Andrea Arcangeli , Ingo Molnar , Johannes Weiner , Hugh Dickins , Thomas Gleixner , Linus Torvalds , Andrew Morton , Linux-MM , LKML On 11/06/2012 04:14 AM, Mel Gorman wrote: > Compaction already has tracepoints to count scanned and isolated pages > but it requires that ftrace be enabled and if that information has to be > written to disk then it can be disruptive. This patch adds vmstat counters > for compaction called compact_migrate_scanned, compact_free_scanned and > compact_isolated. > > With these counters, it is possible to define a basic cost model for > compaction. This approximates of how much work compaction is doing and can > be compared that with an oprofile showing TLB misses and see if the cost of > compaction is being offset by THP for example. Minimally a compaction patch > can be evaluated in terms of whether it increases or decreases cost. The > basic cost model looks like this > Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel -- 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