Re: [PATCH 1/2] Add the soft_limit reclaim in global direct reclaim.

[Michal Hocko <mhocko@suse.cz>]

On Thu 28-04-11 15:37:05, Ying Han wrote:
> We recently added the change in global background reclaim which
> counts the return value of soft_limit reclaim. Now this patch adds
> the similar logic on global direct reclaim.
> 
> We should skip scanning global LRU on shrink_zone if soft_limit reclaim
> does enough work. This is the first step where we start with counting
> the nr_scanned and nr_reclaimed from soft_limit reclaim into global
> scan_control.

Makes sense.

> 
> Signed-off-by: Ying Han <yinghan@google.com>
> ---
>  mm/vmscan.c |   16 ++++++++++++++--
>  1 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b3a569f..84003cc 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1959,11 +1959,14 @@ restart:
>   * If a zone is deemed to be full of pinned pages then just give it a light
>   * scan then give up on it.
>   */
> -static void shrink_zones(int priority, struct zonelist *zonelist,
> +static unsigned long shrink_zones(int priority, struct zonelist *zonelist,
>  					struct scan_control *sc)
>  {
>  	struct zoneref *z;
>  	struct zone *zone;
> +	unsigned long nr_soft_reclaimed;
> +	unsigned long nr_soft_scanned;
> +	unsigned long total_scanned = 0;
>  
>  	for_each_zone_zonelist_nodemask(zone, z, zonelist,
>  					gfp_zone(sc->gfp_mask), sc->nodemask) {
> @@ -1980,8 +1983,17 @@ static void shrink_zones(int priority, struct zonelist *zonelist,
>  				continue;	/* Let kswapd poll it */
>  		}
>  
> +		nr_soft_scanned = 0;
> +		nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
> +							sc->order, sc->gfp_mask,
> +							&nr_soft_scanned);
> +		sc->nr_reclaimed += nr_soft_reclaimed;
> +		total_scanned += nr_soft_scanned;
> +
>  		shrink_zone(priority, zone, sc);

This can cause more aggressive reclaiming, right? Shouldn't we check
whether shrink_zone is still needed?

-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic

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