[PATCH mm-unstable v1 5/8] mm: multi-gen LRU: shuffle should_run_aging()

From: Yu Zhao
Date: Thu Dec 01 2022 - 17:40:08 EST


Move should_run_aging() next to its only caller left.

Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
---
mm/vmscan.c | 124 ++++++++++++++++++++++++++--------------------------
1 file changed, 62 insertions(+), 62 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 67967a4b18a9..0557adce75c5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4452,68 +4452,6 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq,
return true;
}

-static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq,
- struct scan_control *sc, bool can_swap, unsigned long *nr_to_scan)
-{
- int gen, type, zone;
- unsigned long old = 0;
- unsigned long young = 0;
- unsigned long total = 0;
- struct lru_gen_folio *lrugen = &lruvec->lrugen;
- struct mem_cgroup *memcg = lruvec_memcg(lruvec);
- DEFINE_MIN_SEQ(lruvec);
-
- /* whether this lruvec is completely out of cold folios */
- if (min_seq[!can_swap] + MIN_NR_GENS > max_seq) {
- *nr_to_scan = 0;
- return true;
- }
-
- for (type = !can_swap; type < ANON_AND_FILE; type++) {
- unsigned long seq;
-
- for (seq = min_seq[type]; seq <= max_seq; seq++) {
- unsigned long size = 0;
-
- gen = lru_gen_from_seq(seq);
-
- for (zone = 0; zone < MAX_NR_ZONES; zone++)
- size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
-
- total += size;
- if (seq == max_seq)
- young += size;
- else if (seq + MIN_NR_GENS == max_seq)
- old += size;
- }
- }
-
- /* try to scrape all its memory if this memcg was deleted */
- *nr_to_scan = mem_cgroup_online(memcg) ? (total >> sc->priority) : total;
-
- /*
- * The aging tries to be lazy to reduce the overhead, while the eviction
- * stalls when the number of generations reaches MIN_NR_GENS. Hence, the
- * ideal number of generations is MIN_NR_GENS+1.
- */
- if (min_seq[!can_swap] + MIN_NR_GENS < max_seq)
- return false;
-
- /*
- * It's also ideal to spread pages out evenly, i.e., 1/(MIN_NR_GENS+1)
- * of the total number of pages for each generation. A reasonable range
- * for this average portion is [1/MIN_NR_GENS, 1/(MIN_NR_GENS+2)]. The
- * aging cares about the upper bound of hot pages, while the eviction
- * cares about the lower bound of cold pages.
- */
- if (young * MIN_NR_GENS > total)
- return true;
- if (old * (MIN_NR_GENS + 2) < total)
- return true;
-
- return false;
-}
-
static bool lruvec_is_sizable(struct lruvec *lruvec, struct scan_control *sc)
{
int gen, type, zone;
@@ -5097,6 +5035,68 @@ static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swap
return scanned;
}

+static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq,
+ struct scan_control *sc, bool can_swap, unsigned long *nr_to_scan)
+{
+ int gen, type, zone;
+ unsigned long old = 0;
+ unsigned long young = 0;
+ unsigned long total = 0;
+ struct lru_gen_folio *lrugen = &lruvec->lrugen;
+ struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+ DEFINE_MIN_SEQ(lruvec);
+
+ /* whether this lruvec is completely out of cold folios */
+ if (min_seq[!can_swap] + MIN_NR_GENS > max_seq) {
+ *nr_to_scan = 0;
+ return true;
+ }
+
+ for (type = !can_swap; type < ANON_AND_FILE; type++) {
+ unsigned long seq;
+
+ for (seq = min_seq[type]; seq <= max_seq; seq++) {
+ unsigned long size = 0;
+
+ gen = lru_gen_from_seq(seq);
+
+ for (zone = 0; zone < MAX_NR_ZONES; zone++)
+ size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
+
+ total += size;
+ if (seq == max_seq)
+ young += size;
+ else if (seq + MIN_NR_GENS == max_seq)
+ old += size;
+ }
+ }
+
+ /* try to scrape all its memory if this memcg was deleted */
+ *nr_to_scan = mem_cgroup_online(memcg) ? (total >> sc->priority) : total;
+
+ /*
+ * The aging tries to be lazy to reduce the overhead, while the eviction
+ * stalls when the number of generations reaches MIN_NR_GENS. Hence, the
+ * ideal number of generations is MIN_NR_GENS+1.
+ */
+ if (min_seq[!can_swap] + MIN_NR_GENS < max_seq)
+ return false;
+
+ /*
+ * It's also ideal to spread pages out evenly, i.e., 1/(MIN_NR_GENS+1)
+ * of the total number of pages for each generation. A reasonable range
+ * for this average portion is [1/MIN_NR_GENS, 1/(MIN_NR_GENS+2)]. The
+ * aging cares about the upper bound of hot pages, while the eviction
+ * cares about the lower bound of cold pages.
+ */
+ if (young * MIN_NR_GENS > total)
+ return true;
+ if (old * (MIN_NR_GENS + 2) < total)
+ return true;
+
+ return false;
+}
+
/*
* For future optimizations:
* 1. Defer try_to_inc_max_seq() to workqueues to reduce latency for memcg
--
2.39.0.rc0.267.gcb52ba06e7-goog