On Mon, May 30, 2011 at 03:13:45AM +0900, Minchan Kim wrote:
> In __zone_reclaim case, we don't want to shrink mapped page.
> Nonetheless, we have isolated mapped page and re-add it into
> LRU's head. It's unnecessary CPU overhead and makes LRU churning.
>
> Of course, when we isolate the page, the page might be mapped but
> when we try to migrate the page, the page would be not mapped.
> So it could be migrated. But race is rare and although it happens,
> it's no big deal.
>
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
> ---
> mm/vmscan.c | 29 +++++++++++++++++++++--------
> 1 files changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 9972356..39941c7 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1395,6 +1395,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
> unsigned long nr_taken;
> unsigned long nr_anon;
> unsigned long nr_file;
> + enum ISOLATE_PAGE_MODE mode = ISOLATE_NONE;
>
> while (unlikely(too_many_isolated(zone, file, sc))) {
> congestion_wait(BLK_RW_ASYNC, HZ/10);
> @@ -1406,13 +1407,20 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
>
> set_reclaim_mode(priority, sc, false);
> lru_add_drain();
> +
> + if (!sc->may_unmap)
> + mode |= ISOLATE_UNMAPPED;
> + if (!sc->may_writepage)
> + mode |= ISOLATE_CLEAN;
> + mode |= sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
> + ISOLATE_BOTH : ISOLATE_INACTIVE;
Hmm, it would probably be cleaner to fully convert the isolation mode
into independent flags. INACTIVE, ACTIVE, BOTH is currently a
tri-state among flags, which is a bit ugly.
mode = ISOLATE_INACTIVE;
if (!sc->may_unmap)
mode |= ISOLATE_UNMAPPED;
if (!sc->may_writepage)
mode |= ISOLATE_CLEAN;
if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM)
mode |= ISOLATE_ACTIVE;
What do you think?
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