From: Hao Zhang <zhanghao1@xxxxxxxxxx>
The pressure balance calculation is only used in the
fraction scenario. Extract into functions to avoid
unnecessary calculations. This doesn't change current
behaviour.
Signed-off-by: Hao Zhang <zhanghao1@xxxxxxxxxx>
---
mm/vmscan.c | 73 +++++++++++++++++++++++++++++++----------------------
1 file changed, 43 insertions(+), 30 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9a859b7d18d7..97754406dd2e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2367,6 +2367,43 @@ static void prepare_scan_control(pg_data_t *pgdat, struct scan_control *sc)
}
}
+static void calculate_pressure_balance(struct scan_control *sc, int swappiness,
+ u64 *fraction, u64 *denominator)
+{
+ unsigned long anon_cost, file_cost, total_cost;
+ unsigned long ap, fp;
+
+ /*
+ * Calculate the pressure balance between anon and file pages.
+ *
+ * The amount of pressure we put on each LRU is inversely
+ * proportional to the cost of reclaiming each list, as
+ * determined by the share of pages that are refaulting, times
+ * the relative IO cost of bringing back a swapped out
+ * anonymous page vs reloading a filesystem page (swappiness).
+ *
+ * Although we limit that influence to ensure no list gets
+ * left behind completely: at least a third of the pressure is
+ * applied, before swappiness.
+ *
+ * With swappiness at 100, anon and file have equal IO cost.
+ */
+ total_cost = sc->anon_cost + sc->file_cost;
+ anon_cost = total_cost + sc->anon_cost;
+ file_cost = total_cost + sc->file_cost;
+ total_cost = anon_cost + file_cost;
+
+ ap = swappiness * (total_cost + 1);
+ ap /= anon_cost + 1;
+
+ fp = (MAX_SWAPPINESS - swappiness) * (total_cost + 1);
+ fp /= file_cost + 1;
+
+ fraction[WORKINGSET_ANON] = ap;
+ fraction[WORKINGSET_FILE] = fp;
+ *denominator = ap + fp;
+}
+
/*
* Determine how aggressively the anon and file LRU lists should be
* scanned.
@@ -2379,12 +2416,11 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
{
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
- unsigned long anon_cost, file_cost, total_cost;
int swappiness = sc_swappiness(sc, memcg);
u64 fraction[ANON_AND_FILE];
+ bool calculated = false;
u64 denominator = 0; /* gcc */
enum scan_balance scan_balance;
- unsigned long ap, fp;
enum lru_list lru;
/* If we have no swap space, do not bother scanning anon folios. */
@@ -2433,35 +2469,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
}
scan_balance = SCAN_FRACT;
- /*
- * Calculate the pressure balance between anon and file pages.
- *
- * The amount of pressure we put on each LRU is inversely
- * proportional to the cost of reclaiming each list, as
- * determined by the share of pages that are refaulting, times
- * the relative IO cost of bringing back a swapped out
- * anonymous page vs reloading a filesystem page (swappiness).
- *
- * Although we limit that influence to ensure no list gets
- * left behind completely: at least a third of the pressure is
- * applied, before swappiness.
- *
- * With swappiness at 100, anon and file have equal IO cost.
- */
- total_cost = sc->anon_cost + sc->file_cost;
- anon_cost = total_cost + sc->anon_cost;
- file_cost = total_cost + sc->file_cost;
- total_cost = anon_cost + file_cost;
- ap = swappiness * (total_cost + 1);
- ap /= anon_cost + 1;
-
- fp = (MAX_SWAPPINESS - swappiness) * (total_cost + 1);
- fp /= file_cost + 1;
-
- fraction[0] = ap;
- fraction[1] = fp;
- denominator = ap + fp;
out:
for_each_evictable_lru(lru) {
bool file = is_file_lru(lru);
@@ -2544,6 +2552,11 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
/* Scan lists relative to size */
break;
case SCAN_FRACT:
+ if (!calculated) {
+ calculate_pressure_balance(sc, swappiness, fraction, &denominator);
+ calculated = true;
+ }
+
/*
* Scan types proportional to swappiness and
* their relative recent reclaim efficiency.
base-commit: eea6e4b4dfb8859446177c32961c96726d0117be
--
2.25.1
