[dm-devel] [RFC PATCH V2 3/3] dm: support bio polling

[JeffleXu]

On 6/19/21 4:56 AM, Mike Snitzer wrote:
> [you really should've changed the subject of this email to
> "[RFC PATCH V3 3/3] dm: support bio polling"]
> 
> On Fri, Jun 18 2021 at 10:39P -0400,
> Ming Lei <ming.lei at redhat.com> wrote:
> 
>> From 47e523b9ee988317369eaadb96826323cd86819e Mon Sep 17 00:00:00 2001
>> From: Ming Lei <ming.lei at redhat.com>
>> Date: Wed, 16 Jun 2021 16:13:46 +0800
>> Subject: [RFC PATCH V3 3/3] dm: support bio polling
>>
>> Support bio(REQ_POLLED) polling in the following approach:
>>
>> 1) only support io polling on normal READ/WRITE, and other abnormal IOs
>> still fallback on IRQ mode, so the target io is exactly inside the dm
>> io.
>>
>> 2) hold one refcnt on io->io_count after submitting this dm bio with
>> REQ_POLLED
>>
>> 3) support dm native bio splitting, any dm io instance associated with
>> current bio will be added into one list which head is bio->bi_end_io
>> which will be recovered before ending this bio
>>
>> 4) implement .poll_bio() callback, call bio_poll() on the single target
>> bio inside the dm io which is retrieved via bio->bi_bio_drv_data; call
>> dec_pending() after the target io is done in .poll_bio()
>>
>> 4) enable QUEUE_FLAG_POLL if all underlying queues enable QUEUE_FLAG_POLL,
>> which is based on Jeffle's previous patch.
> 
> ^ nit: two "4)", last should be 5.
> 
>>
>> Signed-off-by: Ming Lei <ming.lei at redhat.com>
>> ---
>> V3:
>> 	- covers all comments from Jeffle
> 
> Would really appreciate it if Jeffle could test these changes like he
> did previous dm IO polling patchsets he implemented.  Jeffle?

My pleasure. I would test it today and post the test result as soon as
possible.


-- 
Thanks,
Jeffle