From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Minchan Kim <minchan@kernel.org>,
Hillf Danton <hillf.zj@alibaba-inc.com>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint
Date: Wed, 4 Jan 2017 14:16:55 +0100 [thread overview]
Message-ID: <20170104131653.GH25453@dhcp22.suse.cz> (raw)
In-Reply-To: <646c3551-e794-611c-5247-490bd89133db@suse.cz>
On Wed 04-01-17 13:52:24, Vlastimil Babka wrote:
> On 01/04/2017 11:19 AM, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@suse.com>
> >
> > 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_scanned, nr_taken pages to tell us the LRU isolation
> > effectiveness.
>
> Well, this point is no longer true, is it...
ups, leftover
- nr_take - the number of isolated pages
> > - 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_activated pages which tells us how many pages are kept on the
>
> "nr_activated" is slightly misleading? They remain active, they are not
> being activated (that's why the pgactivate vmstat is also not increased
> on them, right?). I guess rename to "nr_active" ? Or something like
> "nr_remain_active" although that's longer.
will go with nr_active
>
> [...]
>
> > @@ -1857,6 +1859,7 @@ static void move_active_pages_to_lru(struct lruvec *lruvec,
> > unsigned long pgmoved = 0;
> > struct page *page;
> > int nr_pages;
> > + int nr_moved = 0;
> >
> > while (!list_empty(list)) {
> > page = lru_to_page(list);
> > @@ -1882,11 +1885,15 @@ static void move_active_pages_to_lru(struct lruvec *lruvec,
> > spin_lock_irq(&pgdat->lru_lock);
> > } else
> > list_add(&page->lru, pages_to_free);
> > + } else {
> > + nr_moved += nr_pages;
> > }
> > }
> >
> > if (!is_active_lru(lru))
> > __count_vm_events(PGDEACTIVATE, pgmoved);
>
> So we now have pgmoved and nr_moved. One is used for vmstat, other for
> tracepoint, and the only difference is that vmstat includes pages where
> we raced with page being unmapped from all pte's (IIUC?) and thus
> removed from lru, which should be rather rare? I guess those are being
> counted into vmstat only due to how the code evolved from using pagevec.
> If we don't consider them in the tracepoint, then I'd suggest we don't
> count them into vmstat either, and simplify this.
OK, but I would prefer to have this in a separate patch, OK?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2017-01-04 13:17 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-04 10:19 [PATCH 0/7 v2] vm, vmscan: enahance vmscan tracepoints Michal Hocko
2017-01-04 10:19 ` [PATCH 1/7] mm, vmscan: remove unused mm_vmscan_memcg_isolate Michal Hocko
2017-01-04 10:19 ` [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko
2017-01-04 12:52 ` Vlastimil Babka
2017-01-04 13:16 ` Michal Hocko [this message]
2017-01-04 13:34 ` Vlastimil Babka
2017-01-04 13:52 ` Michal Hocko
2017-01-05 5:41 ` Minchan Kim
2017-01-04 10:19 ` [PATCH 3/7] mm, vmscan: show the number of skipped pages in mm_vmscan_lru_isolate Michal Hocko
2017-01-04 10:19 ` [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate tracepoint Michal Hocko
2017-01-05 6:04 ` Minchan Kim
2017-01-05 10:16 ` Michal Hocko
2017-01-05 14:56 ` Mel Gorman
2017-01-05 15:17 ` Michal Hocko
2017-01-04 10:19 ` [PATCH 5/7] mm, vmscan: extract shrink_page_list reclaim counters into a struct Michal Hocko
2017-01-04 14:51 ` Vlastimil Babka
2017-01-04 15:09 ` Michal Hocko
2017-01-04 10:19 ` [PATCH 6/7] mm, vmscan: enhance mm_vmscan_lru_shrink_inactive tracepoint Michal Hocko
2017-01-04 10:19 ` [PATCH 7/7] mm, vmscan: add mm_vmscan_inactive_list_is_low tracepoint Michal Hocko
2017-01-04 10:30 ` [PATCH 0/7 v2] vm, vmscan: enahance vmscan tracepoints Michal Hocko
2017-01-05 8:25 ` Vlastimil Babka
2017-01-05 10:39 ` Michal Hocko
-- strict thread matches above, loose matches on Subject: below --
2016-12-28 15:30 [PATCH 0/7] " Michal Hocko
2016-12-28 15:30 ` [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko
2016-12-29 5:33 ` Minchan Kim
2016-12-29 7:52 ` Michal Hocko
2016-12-30 1:48 ` Minchan Kim
2016-12-30 9:26 ` Michal Hocko
2016-12-30 9:38 ` Hillf Danton
2016-12-30 16:04 ` Minchan Kim
2016-12-30 16:37 ` Michal Hocko
2016-12-30 17:30 ` Michal Hocko
2017-01-03 5:03 ` Minchan Kim
2017-01-03 8:21 ` Michal Hocko
2017-01-04 5:07 ` Minchan Kim
2017-01-04 7:28 ` Vlastimil Babka
2017-01-04 7:50 ` Michal Hocko
2016-12-29 7:44 ` Hillf Danton
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