Messages in this thread | | | Subject | Re: [PATCH] mm-vmscan-dont-mess-with-pgdat-flags-in-memcg-reclaim-v2-fix | From | Andrey Ryabinin <> | Date | Fri, 6 Apr 2018 18:09:54 +0300 |
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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 So the information from ancestor is simply outdated.
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