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

[Minchan Kim <minchan@kernel.org>]

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@suse.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@alibaba-inc.com>
> Acked-by: Mel Gorman <mgorman@suse.de>
> Signed-off-by: Michal Hocko <mhocko@suse.com>

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

Thanks.

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