Re: [PATCH v1 8/9] vmscan: memcg: sleep when flushing stats during reclaim

[Shakeel Butt]

On Mon, Mar 27, 2023 at 11:16 PM Yosry Ahmed <yosryahmed@xxxxxxxxxx> wrote:
>
> Memory reclaim is a sleepable context. Allow sleeping when flushing
> memcg stats to avoid unnecessarily performing a lot of work without
> sleeping. This can slow down reclaim code if flushing stats is taking
> too long, but there is already multiple cond_resched()'s in reclaim
> code.
>
> Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>

Acked-by: Shakeel Butt <shakeelb@xxxxxxxxxx>

> ---
>  mm/vmscan.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index a9511ccb936f..9c1c5e8b24b8 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2845,7 +2845,7 @@ static void prepare_scan_count(pg_data_t *pgdat, struct scan_control *sc)
>          * Flush the memory cgroup stats, so that we read accurate per-memcg
>          * lruvec stats for heuristics.
>          */
> -       mem_cgroup_flush_stats_atomic();
> +       mem_cgroup_flush_stats();

I wonder if we should just replace this with
mem_cgroup_flush_stats_ratelimited().