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    SubjectRe: [PATCH v4 5/7] add profile information for invalidated page reclaim
    Date
    > This patch adds profile information about invalidated page reclaim.
    > It's just for profiling for test so it would be discard when the series
    > are merged.
    >
    > Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
    > Cc: Rik van Riel <riel@redhat.com>
    > Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    > Cc: Wu Fengguang <fengguang.wu@intel.com>
    > Cc: Johannes Weiner <hannes@cmpxchg.org>
    > Cc: Nick Piggin <npiggin@kernel.dk>
    > Cc: Mel Gorman <mel@csn.ul.ie>
    > ---
    > include/linux/vmstat.h | 4 ++--
    > mm/swap.c | 3 +++
    > mm/vmstat.c | 3 +++
    > 3 files changed, 8 insertions(+), 2 deletions(-)

    Today, we have tracepoint. tracepoint has no overhead if it's unused.
    but vmstat has a overhead even if unused.

    Then, all new vmstat proposal should be described why you think it is
    frequently used from administrators.




    >
    > diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
    > index 833e676..c38ad95 100644
    > --- a/include/linux/vmstat.h
    > +++ b/include/linux/vmstat.h
    > @@ -30,8 +30,8 @@
    >
    > enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
    > FOR_ALL_ZONES(PGALLOC),
    > - PGFREE, PGACTIVATE, PGDEACTIVATE,
    > - PGFAULT, PGMAJFAULT,
    > + PGFREE, PGACTIVATE, PGDEACTIVATE, PGINVALIDATE,
    > + PGRECLAIM, PGFAULT, PGMAJFAULT,
    > FOR_ALL_ZONES(PGREFILL),
    > FOR_ALL_ZONES(PGSTEAL),
    > FOR_ALL_ZONES(PGSCAN_KSWAPD),
    > diff --git a/mm/swap.c b/mm/swap.c
    > index 0f23998..2f21e6e 100644
    > --- a/mm/swap.c
    > +++ b/mm/swap.c
    > @@ -317,6 +317,7 @@ static void lru_deactivate(struct page *page, struct zone *zone)
    > * is _really_ small and it's non-critical problem.
    > */
    > SetPageReclaim(page);
    > + __count_vm_event(PGRECLAIM);

    Um. No.
    This is not reclaim operation anyway. Userland folks shouldn't know
    you override PG_reclaim. It's implementaion internal information.



    > } else {
    > /*
    > * The page's writeback ends up during pagevec
    > @@ -328,6 +329,8 @@ static void lru_deactivate(struct page *page, struct zone *zone)
    >
    > if (active)
    > __count_vm_event(PGDEACTIVATE);
    > +
    > + __count_vm_event(PGINVALIDATE);
    > update_page_reclaim_stat(zone, page, file, 0);

    I have similar complains as above.
    If you use PGINVALIDATE, other invalidate pass should update this counter too.


    > }
    >
    > diff --git a/mm/vmstat.c b/mm/vmstat.c
    > index 3555636..ef6102d 100644
    > --- a/mm/vmstat.c
    > +++ b/mm/vmstat.c
    > @@ -818,6 +818,9 @@ static const char * const vmstat_text[] = {
    > "pgactivate",
    > "pgdeactivate",
    >
    > + "pginvalidate",
    > + "pgreclaim",
    > +
    > "pgfault",
    > "pgmajfault",
    >
    > --
    > 1.7.0.4
    >





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