blk-mq: switch to percpu-ida for tag management
Using percpu-ida to manage blk-mq tags. the percpu-ida has similar algorithm
like the blk-mq-tag. The difference is when a cpu can't allocate tags
blk-mq-tag uses ipi to purge remote cpu cache and percpu-ida directly purges
remote cpu cache. In practice (testing null_blk), the percpu-ida approach is
much faster when total tags aren't enough.
My test is done in a 2 sockets machine, 12 process cross the 2 sockets. So if
there is lock contention or ipi, should be stressed heavily. Testing is done
for null-blk.
hw_queue_depth nopatch iops patch iops
64 ~800k/s ~1470k/s
2048 ~4470k/s ~4340k/s
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1 file changed
