On 2022/03/29 20:44, Jens Axboe wrote:
On 3/29/22 3:40 AM, Yu Kuai wrote:
Tag preemption is the default behaviour, specifically blk_mq_get_tag()
will try to get tag unconditionally, which means a new io can preempt tag
even if there are lots of ios that are waiting for tags.
This patch introduce a new flag, prepare to disable such behaviour, in
order to optimize io performance for large random io for HHD.
Not sure why we need a flag for this behavior. Does it ever make sense
to allow preempting waiters, jumping the queue?
Hi,
I was thinking using the flag to control the new behavior, in order to
reduce the impact on general path.
If wake up path is handled properly, I think it's ok to disable
preempting tags.
Thanks
Kuai
