Reflects ceph.git commit 4551fee9ad89d0427ed865d766d0d44004d3e3e1.
Signed-off-by: Ilya Dryomov <[email protected]>
---
net/ceph/crush/mapper.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/net/ceph/crush/mapper.c b/net/ceph/crush/mapper.c
index caeb1066bea3..77b7a73e65cf 100644
--- a/net/ceph/crush/mapper.c
+++ b/net/ceph/crush/mapper.c
@@ -514,6 +514,14 @@ static void crush_choose_indep(const struct crush_map *map,
/* choose through intervening buckets */
for (;;) {
+ /* note: we base the choice on the position
+ * even in the nested call. that means that
+ * if the first layer chooses the same bucket
+ * in a different position, we will tend to
+ * choose a different item in that bucket.
+ * this will involve more devices in data
+ * movement and tend to distribute the load.
+ */
r = rep;
/* be careful */
--
1.7.10.4
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