[patch 6/8] mm: vmscan: clean up get_scan_count()
From: Johannes Weiner <hannes@cmpxchg.org>
Date: 2012-12-12 21:44:50
Also in:
lkml
Subsystem:
memory management, memory management - mglru (multi-gen lru), memory management - reclaim, the rest · Maintainers:
Andrew Morton, Johannes Weiner, Linus Torvalds
Reclaim pressure balance between anon and file pages is calculated
through a tuple of numerators and a shared denominator.
Exceptional cases that want to force-scan anon or file pages configure
the numerators and denominator such that one list is preferred, which
is not necessarily the most obvious way:
fraction[0] = 1;
fraction[1] = 0;
denominator = 1;
goto out;
Make this easier by making the force-scan cases explicit and use the
fractionals only in case they are calculated from reclaim history.
And bring the variable declarations/definitions in order.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
mm/vmscan.c | 46 ++++++++++++++++++++++++++++------------------
1 file changed, 28 insertions(+), 18 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 05475e1..e20385a 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c@@ -1626,6 +1626,13 @@ static int vmscan_swappiness(struct scan_control *sc) return mem_cgroup_swappiness(sc->target_mem_cgroup); } +enum scan_balance { + SCAN_EQUAL, + SCAN_FRACT, + SCAN_ANON, + SCAN_FILE, +}; + /* * Determine how aggressively the anon and file LRU lists should be * scanned. The relative value of each set of LRU lists is determined
@@ -1638,14 +1645,15 @@ static int vmscan_swappiness(struct scan_control *sc) static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, unsigned long *nr) { - unsigned long anon, file, free; + struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; + u64 fraction[2], uninitialized_var(denominator); + struct zone *zone = lruvec_zone(lruvec); unsigned long anon_prio, file_prio; + enum scan_balance scan_balance; + unsigned long anon, file, free; + bool force_scan = false; unsigned long ap, fp; - struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; - u64 fraction[2], denominator; enum lru_list lru; - bool force_scan = false; - struct zone *zone = lruvec_zone(lruvec); /* * If the zone or memcg is small, nr[l] can be 0. This
@@ -1664,9 +1672,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, /* If we have no swap space, do not bother scanning anon pages. */ if (!sc->may_swap || (nr_swap_pages <= 0)) { - fraction[0] = 0; - fraction[1] = 1; - denominator = 1; + scan_balance = SCAN_FILE; goto out; }
@@ -1675,9 +1681,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, * system is close to OOM, scan both anon and file equally. */ if (!sc->priority) { - fraction[0] = 1; - fraction[1] = 1; - denominator = 1; + scan_balance = SCAN_EQUAL; goto out; }
@@ -1686,9 +1690,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, * anything from the anonymous working set right now. */ if (!inactive_file_is_low(lruvec)) { - fraction[0] = 0; - fraction[1] = 1; - denominator = 1; + scan_balance = SCAN_FILE; goto out; }
@@ -1706,13 +1708,13 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, if (global_reclaim(sc)) { free = zone_page_state(zone, NR_FREE_PAGES); if (unlikely(file + free <= high_wmark_pages(zone))) { - fraction[0] = 1; - fraction[1] = 0; - denominator = 1; + scan_balance = SCAN_ANON; goto out; } } + scan_balance = SCAN_FRACT; + /* * With swappiness at 100, anonymous and file have the same priority. * This scanning priority is essentially the inverse of IO cost.
@@ -1765,9 +1767,17 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, size = get_lru_size(lruvec, lru); scan = size >> sc->priority; + if (!scan && force_scan) scan = min(size, SWAP_CLUSTER_MAX); - scan = div64_u64(scan * fraction[file], denominator); + + if (scan_balance == SCAN_EQUAL) + ; /* scan relative to size */ + else if (scan_balance == SCAN_FRACT) + scan = div64_u64(scan * fraction[file], denominator); + else if ((scan_balance == SCAN_FILE) != file) + scan = 0; + nr[lru] = scan; } }
--
1.7.11.7
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