mm/vmscan: extract calculated pressure balance as a function

Extract pressure balance calculation into a function.This doesn't change
current behaviour.

[akpm@linux-foundation.org: 80-col wrapping]
Link: https://lkml.kernel.org/r/tencent_735DB36A2306C08B8568049E4C0B99716C07@qq.com
Signed-off-by: Hao Zhang <zhanghao1@kylinos.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index fc4951d23b97bbd0342f93ab5a861f6ffc3bce94..bc18260201593d1c9d49a61862d39ae2bb9572de 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2400,6 +2400,43 @@ static void prepare_scan_control(pg_data_t *pgdat, struct scan_control *sc)
        }
 }
 
+static inline 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.
@@ -2412,12 +2449,10 @@ 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];
        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. */
@@ -2466,35 +2501,8 @@ 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;
+       calculate_pressure_balance(sc, swappiness, fraction, &denominator);
 
-       fraction[0] = ap;
-       fraction[1] = fp;
-       denominator = ap + fp;
 out:
        for_each_evictable_lru(lru) {
                bool file = is_file_lru(lru);