blk-mq: Fix wrong wakeup batch configuration which will cause hang

Commit 180dccb0dba4f ("blk-mq: fix tag_get wait task can't be
awakened") will recalculate wake_batch when incrementing or decrementing
active_queues to avoid wake_batch > hctx_max_depth. At the same time, in
order to not affect performance as much as possible, the minimum wakeup
batch is set to 4. But when the QD is small (such as QD=1), if inc or dec
active_queues increases wakeup batch, that can lead to a hang:

Fix this problem with the following strategies:
QD          :  >= 32 | < 32
---------------------------------
wakeup batch:  8~4   | 3~1

Fixes: 180dccb0dba4f ("blk-mq: fix tag_get wait task can't be awakened")
Link: https://lore.kernel.org/linux-block/[email protected]/T/#t
Reported-by: Alex Xu (Hello71) <[email protected]>
Signed-off-by: Laibin Qiu <[email protected]>
Tested-by: Alex Xu (Hello71) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions