(2011/07/11 22:01), Mel Gorman wrote:
> With zone_reclaim_mode enabled, it's possible for zones to be considered
> full in the zonelist_cache so they are skipped in the future. If the
> process enters direct reclaim, the ZLC may still consider zones to be
> full even after reclaiming pages. Reconsider all zones for allocation
> if direct reclaim returns successfully.
>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Hmmm...
I like the concept, but I'm worry about a corner case a bit.
If users are using cpusets/mempolicy, direct reclaim don't scan all zones.
Then, zlc_clear_zones_full() seems too aggressive operation.
Instead, couldn't we turn zlc->fullzones off from kswapd?
> ---
> mm/page_alloc.c | 19 +++++++++++++++++++
> 1 files changed, 19 insertions(+), 0 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 6913854..149409c 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1616,6 +1616,21 @@ static void zlc_mark_zone_full(struct zonelist *zonelist, struct zoneref *z)
> set_bit(i, zlc->fullzones);
> }
>
> +/*
> + * clear all zones full, called after direct reclaim makes progress so that
> + * a zone that was recently full is not skipped over for up to a second
> + */
> +static void zlc_clear_zones_full(struct zonelist *zonelist)
> +{
> + struct zonelist_cache *zlc; /* cached zonelist speedup info */
> +
> + zlc = zonelist->zlcache_ptr;
> + if (!zlc)
> + return;
> +
> + bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
> +}
> +
> #else /* CONFIG_NUMA */
>
> static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags)
> @@ -1963,6 +1978,10 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
> if (unlikely(!(*did_some_progress)))
> return NULL;
>
> + /* After successful reclaim, reconsider all zones for allocation */
> + if (NUMA_BUILD)
> + zlc_clear_zones_full(zonelist);
> +
> retry:
> page = get_page_from_freelist(gfp_mask, nodemask, order,
> zonelist, high_zoneidx,
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>