3.16.7-ckt2 -stable review patch. If anyone has any objections, please let me
know.
------------------
From: Mikulas Patocka <mpato...@redhat.com>
commit 0e825862f3c04cee40e25f55680333728a4ffa9b upstream.
When __scan frees the required number of buffer entries that the
shrinker requested (nr_to_scan becomes zero) it must return. Before
this fix the __scan code exited only the inner loop and continued in the
outer loop -- which could result in reduced performance due to extra
buffers being freed (e.g. unnecessarily evicted thinp metadata needing
to be synchronously re-read into bufio's cache).
Also, move dm_bufio_cond_resched to __scan's inner loop, so that
iterating the bufio client's lru lists doesn't result in scheduling
latency.
Reported-by: Joe Thornber <thorn...@redhat.com>
Signed-off-by: Mikulas Patocka <mpato...@redhat.com>
Signed-off-by: Mike Snitzer <snit...@redhat.com>
Signed-off-by: Luis Henriques <luis.henriq...@canonical.com>
---
drivers/md/dm-bufio.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index da2ebac231b9..598ba99d2e15 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1486,9 +1486,9 @@ static long __scan(struct dm_bufio_client *c, unsigned
long nr_to_scan,
list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) {
freed += __cleanup_old_buffer(b, gfp_mask, 0);
if (!--nr_to_scan)
- break;
+ return freed;
+ dm_bufio_cond_resched();
}
- dm_bufio_cond_resched();
}
return freed;
}
--
2.1.0
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