From: Kalesh Singh Date: Tue, 23 May 2023 20:59:21 +0000 (-0700) Subject: Multi-gen LRU: fix workingset accounting X-Git-Tag: v6.6.7~2549^2~241 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3af0191a594d5ca5d6d2e3602b5d4284c6835e77;p=platform%2Fkernel%2Flinux-starfive.git Multi-gen LRU: fix workingset accounting On Android app cycle workloads, MGLRU showed a significant reduction in workingset refaults although pgpgin/pswpin remained relatively unchanged. This indicated MGLRU may be undercounting workingset refaults. This has impact on userspace programs, like Android's LMKD, that monitor workingset refault statistics to detect thrashing. It was found that refaults were only accounted if the MGLRU shadow entry was for a recently evicted folio. However, recently evicted folios should be accounted as workingset activation, and refaults should be accounted regardless of recency. Fix MGLRU's workingset refault and activation accounting to more closely match that of the conventional active/inactive LRU. Link: https://lkml.kernel.org/r/20230523205922.3852731-1-kaleshsingh@google.com Fixes: ac35a4902374 ("mm: multi-gen LRU: minimal implementation") Signed-off-by: Kalesh Singh Reported-by: Charan Teja Kalla Acked-by: Yu Zhao Cc: Brian Geffon Cc: Jan Alexander Steffens (heftig) Cc: Oleksandr Natalenko Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton --- diff --git a/mm/vmscan.c b/mm/vmscan.c index dbbfcc6..3024b46 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4925,7 +4925,6 @@ static bool sort_folio(struct lruvec *lruvec, struct folio *folio, int tier_idx) WRITE_ONCE(lrugen->protected[hist][type][tier - 1], lrugen->protected[hist][type][tier - 1] + delta); - __mod_lruvec_state(lruvec, WORKINGSET_ACTIVATE_BASE + type, delta); return true; } diff --git a/mm/workingset.c b/mm/workingset.c index 5796e92..4686ae3 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -278,6 +278,7 @@ static bool lru_gen_test_recent(void *shadow, bool file, struct lruvec **lruvec, static void lru_gen_refault(struct folio *folio, void *shadow) { + bool recent; int hist, tier, refs; bool workingset; unsigned long token; @@ -288,10 +289,13 @@ static void lru_gen_refault(struct folio *folio, void *shadow) rcu_read_lock(); - if (!lru_gen_test_recent(shadow, type, &lruvec, &token, &workingset)) + recent = lru_gen_test_recent(shadow, type, &lruvec, &token, &workingset); + if (lruvec != folio_lruvec(folio)) goto unlock; - if (lruvec != folio_lruvec(folio)) + mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + type, delta); + + if (!recent) goto unlock; lrugen = &lruvec->lrugen; @@ -302,7 +306,7 @@ static void lru_gen_refault(struct folio *folio, void *shadow) tier = lru_tier_from_refs(refs); atomic_long_add(delta, &lrugen->refaulted[hist][type][tier]); - mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + type, delta); + mod_lruvec_state(lruvec, WORKINGSET_ACTIVATE_BASE + type, delta); /* * Count the following two cases as stalls: