Re: [PATCH] mm: Do not deactivate when the cgroup has plenty inactive page

[Michal Hocko <mhocko@suse.com>]

On Fri 25-09-20 19:49:12, zhongjiang-ali wrote:
> After appling the series patches(mm: fix page aging across multiple cgroups),
> cgroup memory reclaim strategy is based on reclaim root's inactive:active
> ratio. if the target lruvec need to deactivate, its children cgroup also will
> deactivate. That will result in hot page to be reclaimed and other cgroup's
> cold page will be left, which is not expected.
> 
> The patch will not force deactivate when inactive_is_low is not true unless
> we has scanned the inactive list and memory is unable to reclaim.

Do you have any data to present?

> Signed-off-by: zhongjiang-ali <zhongjiang-ali@linux.alibaba.com>
> ---
>  mm/vmscan.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 466fc31..77d395f 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2407,8 +2407,21 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
>  		case SCAN_FILE:
>  		case SCAN_ANON:
>  			/* Scan one type exclusively */
> -			if ((scan_balance == SCAN_FILE) != file)
> +			if ((scan_balance == SCAN_FILE) != file) {
>  				scan = 0;
> +			} else {
> +				/*
> +				 * Reclaim memory is based on the root's inactive: active
> +				 * ratio, but it is possible that silbing cgroup has a lot
> +				 * of cold memory to reclaim rather than reclaim the hot
> +				 * cache in the current cgroup.
> +				 */
> +				if (!sc->force_deactivate && is_active_lru(lru) &&
> +						!inactive_is_low(lruvec, lru - LRU_ACTIVE)) {
> +					if (sc->may_deactivate & (1 << file))
> +						scan = 0;
> +				}
> +			}
>  			break;
>  		default:
>  			/* Look ma, no brain */
> -- 
> 1.8.3.1
> 

-- 
Michal Hocko
SUSE Labs