On Mon 23-01-17 13:16:39, Johannes Weiner wrote:
> Direct reclaim has been replaced by kswapd reclaim in pretty much all
> common memory pressure situations, so this code most likely doesn't
> accomplish the described effect anymore. The previous patch wakes up
> flushers for all reclaimers when we encounter dirty pages at the tail
> end of the LRU. Remove the crufty old direct reclaim invocation.
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> mm/vmscan.c | 17 -----------------
> 1 file changed, 17 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 56ea8d24041f..915fc658de41 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2757,8 +2757,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
> struct scan_control *sc)
> {
> int initial_priority = sc->priority;
> - unsigned long total_scanned = 0;
> - unsigned long writeback_threshold;
> retry:
> delayacct_freepages_start();
>
> @@ -2771,7 +2769,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
> sc->nr_scanned = 0;
> shrink_zones(zonelist, sc);
>
> - total_scanned += sc->nr_scanned;
> if (sc->nr_reclaimed >= sc->nr_to_reclaim)
> break;
>
> @@ -2784,20 +2781,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
> */
> if (sc->priority < DEF_PRIORITY - 2)
> sc->may_writepage = 1;
> -
> - /*
> - * Try to write back as many pages as we just scanned. This
> - * tends to cause slow streaming writers to write data to the
> - * disk smoothly, at the dirtying rate, which is nice. But
> - * that's undesirable in laptop mode, where we *want* lumpy
> - * writeout. So in laptop mode, write out the whole world.
> - */
> - writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2;
> - if (total_scanned > writeback_threshold) {
> - wakeup_flusher_threads(laptop_mode ? 0 : total_scanned,
> - WB_REASON_VMSCAN);
> - sc->may_writepage = 1;
> - }
> } while (--sc->priority >= 0);
>
> delayacct_freepages_end();
> --
> 2.11.0
>
> --
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--
Michal Hocko
SUSE Labs
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