Re: [PATCH] mm-vmscan-dont-mess-with-pgdat-flags-in-memcg-reclaim-v2-fix
From: Shakeel Butt
Date: Fri Apr 06 2018 - 11:22:24 EST
On Fri, Apr 6, 2018 at 8:09 AM, Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> wrote:
> On 04/06/2018 05:37 PM, Shakeel Butt wrote:
>>> @@ -2482,7 +2494,7 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat,
>>> static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg)
>>> return test_bit(PGDAT_CONGESTED, &pgdat->flags) ||
>>> - (memcg && test_memcg_bit(PGDAT_CONGESTED, memcg));
>>> + (memcg && memcg_congested(pgdat, memcg));
>> I am wondering if we should check all ancestors for congestion as
>> well. Maybe a parallel memcg reclaimer might have set some ancestor of
>> this memcg to congested.
> Why? If ancestor is congested but its child (the one we currently reclaim) is not,
> it could mean only 2 things:
> - Either child use mostly anon and inactive file lru is small (file_lru >> priority == 0)
> so it's not congested.
> - Or the child was congested recently (at the time when ancestor scanned this group),
> but not anymore. So the information from ancestor is simply outdated.
Oh yeah, you explained in the other email as well. Thanks.
I think Andrew will squash this patch with the previous one. Andrew,
please add following in the squashed patch.
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>