Re: [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints

From	Michal Hocko <mhocko@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints
Date	2016-12-30 10:40 +0100
Message-ID	<sU1Pj-2xO-3@gated-at.bofh.it> (permalink)
References	<sTouB-1H0-1@gated-at.bofh.it> <sU1vX-2rD-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Fri 30-12-16 09:11:17, Mel Gorman wrote:
> On Wed, Dec 28, 2016 at 04:30:25PM +0100, Michal Hocko wrote:
> > Hi,
> > while debugging [1] I've realized that there is some room for
> > improvements in the tracepoints set we offer currently. I had hard times
> > to make any conclusion from the existing ones. The resulting problem
> > turned out to be active list aging [2] and we are missing at least two
> > tracepoints to debug such a problem.
> > 
> > Some existing tracepoints could export more information to see _why_ the
> > reclaim progress cannot be made not only _how much_ we could reclaim.
> > The later could be seen quite reasonably from the vmstat counters
> > already. It can be argued that we are showing too many implementation
> > details in those tracepoints but I consider them way too lowlevel
> > already to be usable by any kernel independent userspace. I would be
> > _really_ surprised if anything but debugging tools have used them.
> > 
> > Any feedback is highly appreciated.
> > 
> 
> There is some minor overhead introduced in some paths regardless of
> whether the tracepoints are active or not but I suspect it's negligible
> in the context of the overhead of reclaim in general so;

I will work on improving some of them. E.g. I've dropped the change to
free_hot_cold_page_list because that is indeed a hot path but other than
that there shouldn't be any even medium hot path which should see any
overhead I can see. If you are aware of any, please let me know and I
will think about how to improve it.
 
> Acked-by: Mel Gorman <mgorman@suse.de>

Thanks!
-- 
Michal Hocko
SUSE Labs

Thread

[PATCH 0/7] vm, vmscan: enahance vmscan tracepoints Michal Hocko <mhocko@kernel.org> - 2016-12-28 16:40 +0100
  [PATCH 7/7] mm, vmscan: add mm_vmscan_inactive_list_is_low tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-28 16:40 +0100
    Re: [PATCH 7/7] mm, vmscan: add mm_vmscan_inactive_list_is_low tracepoint "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-12-29 09:30 +0100
  [PATCH 1/7] mm, vmscan: remove unused mm_vmscan_memcg_isolate Michal Hocko <mhocko@kernel.org> - 2016-12-28 16:40 +0100
    Re: [PATCH 1/7] mm, vmscan: remove unused mm_vmscan_memcg_isolate "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-12-29 08:50 +0100
  [PATCH 5/7] mm, vmscan: extract shrink_page_list reclaim counters into a struct Michal Hocko <mhocko@kernel.org> - 2016-12-28 16:40 +0100
    Re: [PATCH 5/7] mm, vmscan: extract shrink_page_list reclaim counters into a struct "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-12-29 09:10 +0100
  [PATCH 6/7] mm, vmscan: enhance mm_vmscan_lru_shrink_inactive tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-28 16:40 +0100
    Re: [PATCH 6/7] mm, vmscan: enhance mm_vmscan_lru_shrink_inactive tracepoint "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-12-29 09:20 +0100
  [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-28 16:40 +0100
    Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Nikolay Borisov <n.borisov.lkml@gmail.com> - 2016-12-28 17:00 +0100
      Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-28 17:10 +0100
        Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Nikolay Borisov <n.borisov.lkml@gmail.com> - 2016-12-28 17:50 +0100
          Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-28 18:00 +0100
    Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Minchan Kim <minchan@kernel.org> - 2016-12-29 07:10 +0100
      Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-29 09:00 +0100
        Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Minchan Kim <minchan@kernel.org> - 2016-12-30 03:00 +0100
          Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-30 10:40 +0100
    Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate tracepoint "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-12-29 09:00 +0100
    Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate  tracepoint Vlastimil Babka <vbabka@suse.cz> - 2017-01-03 18:10 +0100
  [PATCH 3/7] mm, vmscan: show the number of skipped pages in mm_vmscan_lru_isolate Michal Hocko <mhocko@kernel.org> - 2016-12-28 16:40 +0100
    Re: [PATCH 3/7] mm, vmscan: show the number of skipped pages in  mm_vmscan_lru_isolate Minchan Kim <minchan@kernel.org> - 2016-12-29 07:00 +0100
    Re: [PATCH 3/7] mm, vmscan: show the number of skipped pages in mm_vmscan_lru_isolate "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-12-29 09:00 +0100
    Re: [PATCH 3/7] mm, vmscan: show the number of skipped pages in  mm_vmscan_lru_isolate Vlastimil Babka <vbabka@suse.cz> - 2017-01-03 18:30 +0100
  [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-28 16:40 +0100
    Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Minchan Kim <minchan@kernel.org> - 2016-12-29 06:40 +0100
      Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-29 09:00 +0100
        Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Minchan Kim <minchan@kernel.org> - 2016-12-30 02:50 +0100
          Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-30 10:30 +0100
            Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-12-30 10:50 +0100
            Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Minchan Kim <minchan@kernel.org> - 2016-12-30 17:10 +0100
              Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-30 17:40 +0100
                Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko <mhocko@kernel.org> - 2016-12-30 18:40 +0100
                Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Minchan Kim <minchan@kernel.org> - 2017-01-03 06:10 +0100
                Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko <mhocko@kernel.org> - 2017-01-03 09:30 +0100
    Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-12-29 09:00 +0100
  Re: [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints Mel Gorman <mgorman@suse.de> - 2016-12-30 10:20 +0100
    Re: [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints Michal Hocko <mhocko@kernel.org> - 2016-12-30 10:40 +0100
      Re: [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints Mel Gorman <mgorman@suse.de> - 2016-12-30 11:30 +0100

csiph-web