vmscan: add customisable shrinker batch size
For shrinkers that have their own cond_resched* calls, having
shrink_slab break the work down into small batches is not
paticularly efficient. Add a custom batchsize field to the struct
shrinker so that shrinkers can use a larger batch size if they
desire.
A value of zero (uninitialised) means "use the default", so
behaviour is unchanged by this patch.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 3874224..febbc04 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -253,6 +253,8 @@
int shrink_ret = 0;
long nr;
long new_nr;
+ long batch_size = shrinker->batch ? shrinker->batch
+ : SHRINK_BATCH;
/*
* copy the current shrinker scan count into a local variable
@@ -303,19 +305,18 @@
nr_pages_scanned, lru_pages,
max_pass, delta, total_scan);
- while (total_scan >= SHRINK_BATCH) {
- long this_scan = SHRINK_BATCH;
+ while (total_scan >= batch_size) {
int nr_before;
nr_before = do_shrinker_shrink(shrinker, shrink, 0);
shrink_ret = do_shrinker_shrink(shrinker, shrink,
- this_scan);
+ batch_size);
if (shrink_ret == -1)
break;
if (shrink_ret < nr_before)
ret += nr_before - shrink_ret;
- count_vm_events(SLABS_SCANNED, this_scan);
- total_scan -= this_scan;
+ count_vm_events(SLABS_SCANNED, batch_size);
+ total_scan -= batch_size;
cond_resched();
}