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-rw-r--r--block/bfq-iosched.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 2a84294b0525..a3f59d3065b3 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -5860,7 +5860,17 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
1UL<<(BFQ_RATE_SHIFT - 10))
bfq_update_rate_reset(bfqd, NULL);
bfqd->last_completion = now_ns;
- bfqd->last_completed_rq_bfqq = bfqq;
+ /*
+ * Shared queues are likely to receive I/O at a high
+ * rate. This may deceptively let them be considered as wakers
+ * of other queues. But a false waker will unjustly steal
+ * bandwidth to its supposedly woken queue. So considering
+ * also shared queues in the waking mechanism may cause more
+ * control troubles than throughput benefits. Then do not set
+ * last_completed_rq_bfqq to bfqq if bfqq is a shared queue.
+ */
+ if (!bfq_bfqq_coop(bfqq))
+ bfqd->last_completed_rq_bfqq = bfqq;
/*
* If we are waiting to discover whether the request pattern