Re: [PATCH v1 5/9] block: loop: convert to blk-mq

From: Benjamin LaHaise
Date: Wed Aug 27 2014 - 12:30:01 EST

On Wed, Aug 27, 2014 at 08:08:59PM +0400, Maxim Patlasov wrote:
> 1) /dev/loop0 of 3.17.0-rc1 with Ming's patches applied -- 11K iops
> 2) the same as above, but call loop_queue_work() directly from
> loop_queue_rq() -- 270K iops
> 3) /dev/nullb0 of 3.17.0-rc1 -- 380K iops
> Taking into account so big difference (11K vs. 270K), would it be worthy
> to implement pure non-blocking version of aio_kernel_submit() returning
> error if blocking needed? Then loop driver (or any other in-kernel user)
> might firstly try that non-blocking submit as fast-path, and, only if
> it's failed, fall back to queueing.

What filesystem is the backing file for loop0 on? O_DIRECT access as
Ming's patches use should be non-blocking, and if not, that's something
to fix.

"Thought is the essence of where you are now."
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