[PATCH 16/20] blkio: do not select co-operating queues from different cfq groups

[Vivek Goyal]

o Select co-operating queue from same group not from a different cfq_group
  to maintain the notion of fairness and isolation between groups.

Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
 block/cfq-iosched.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 98dbead..020d6dd 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1635,6 +1635,10 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
 	if (!cfqq)
 		return NULL;
 
+	/* If new queue belongs to different cfq_group, don't choose it */
+	if (cfqq_to_cfqg(cur_cfqq) != cfqq_to_cfqg(cfqq))
+		return NULL;
+
 	if (cfq_cfqq_coop(cfqq))
 		return NULL;
 
-- 
1.6.2.5

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