linux-kernel - Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint

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Message-ID: <20170105054119.GB24371@bbox>
Date:   Thu, 5 Jan 2017 14:41:19 +0900
From:   Minchan Kim <minchan@...nel.org>
To:     Michal Hocko <mhocko@...nel.org>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...e.de>,
        Johannes Weiner <hannes@...xchg.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Hillf Danton <hillf.zj@...baba-inc.com>, <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint

On Wed, Jan 04, 2017 at 02:52:47PM +0100, Michal Hocko wrote:
> With fixed triggered by Vlastimil it should be like this.
> ---
> From b3a1480b54bf10924a9cd09c6d8b274fc81ca4ad Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@...e.com>
> Date: Tue, 27 Dec 2016 13:18:20 +0100
> Subject: [PATCH] mm, vmscan: add active list aging tracepoint
> 
> Our reclaim process has several tracepoints to tell us more about how
> things are progressing. We are, however, missing a tracepoint to track
> active list aging. Introduce mm_vmscan_lru_shrink_active which reports
> the number of
> 	- nr_taken is number of isolated pages from the active list
> 	- nr_referenced pages which tells us that we are hitting referenced
> 	  pages which are deactivated. If this is a large part of the
> 	  reported nr_deactivated pages then we might be hitting into
> 	  the active list too early because they might be still part of
> 	  the working set. This might help to debug performance issues.
> 	- nr_active pages which tells us how many pages are kept on the
> 	  active list - mostly exec file backed pages. A high number can
> 	  indicate that we might be trashing on executables.
> 
> Changes since v1
> - report nr_taken pages as per Minchan
> - report nr_activated as per Minchan
> - do not report nr_freed pages because that would add a tiny overhead to
>   free_hot_cold_page_list which is a hot path
> - do not report nr_unevictable because we can report this number via a
>   different and more generic tracepoint in putback_lru_page
> - fix move_active_pages_to_lru to report proper page count when we hit
>   into large pages
> - drop nr_scanned because this can be obtained from
>   trace_mm_vmscan_lru_isolate as per Minchan
> 
> Acked-by: Hillf Danton <hillf.zj@...baba-inc.com>
> Acked-by: Mel Gorman <mgorman@...e.de>
> Signed-off-by: Michal Hocko <mhocko@...e.com>

Acked-by: Minchan Kim <minchan@...nel.org>

Thanks.