bfq: Allow current waker to defend against a tentative one

[ Upstream commit c5ac56bb6110e42e79d3106866658376b2e48ab9 ]

The code in bfq_check_waker() ignores wake up events from the current
waker. This makes it more likely we select a new tentative waker
although the current one is generating more wake up events. Treat
current waker the same way as any other process and allow it to reset
the waker detection logic.

Fixes: 71217df39dc6 ("block, bfq: make waker-queue detection more robust")
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220519105235.31397-2-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index a2aefb4..343ca55 100644 (file)
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2022,8 +2022,7 @@ static void bfq_check_waker(struct bfq_data *bfqd, struct bfq_queue *bfqq,
        if (!bfqd->last_completed_rq_bfqq ||
            bfqd->last_completed_rq_bfqq == bfqq ||
            bfq_bfqq_has_short_ttime(bfqq) ||
-           now_ns - bfqd->last_completion >= 4 * NSEC_PER_MSEC ||
-           bfqd->last_completed_rq_bfqq == bfqq->waker_bfqq)
+           now_ns - bfqd->last_completion >= 4 * NSEC_PER_MSEC)
                return;
 
        if (bfqd->last_completed_rq_bfqq !=