shrink_slab() queries each slab cache to get the number of
elements in it. In most cases such queries are cheap but,
on some caches. For example, Android low-memory-killer,
which is operates as a slab shrinker, does relatively
long calculation once invoked and it is quite expensive.
This patch removes redundant queries to shrinker function
in the loop of shrink batch.
Signed-off-by: Heesub Shin <heesub.shin@xxxxxxxxxxx>
---
mm/vmscan.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index fa6a853..11b6695 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -282,9 +282,8 @@ unsigned long shrink_slab(struct shrink_control *shrink,
max_pass, delta, total_scan);
while (total_scan >= batch_size) {
- int nr_before;
+ int nr_before = max_pass;
- nr_before = do_shrinker_shrink(shrinker, shrink, 0);
shrink_ret = do_shrinker_shrink(shrinker, shrink,
batch_size);
if (shrink_ret == -1)
@@ -293,6 +292,7 @@ unsigned long shrink_slab(struct shrink_control *shrink,
ret += nr_before - shrink_ret;
count_vm_events(SLABS_SCANNED, batch_size);
total_scan -= batch_size;
+ max_pass = shrink_ret;
cond_resched();
}
--
1.8.3.1
--
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