[V8,0/3] blk-mq: refactor code of issue request directly

Message

jianchao.wang Nov. 15, 2018, 3:12 a.m. UTC

Hi Jens

Please consider this patchset for 4.21.
It refactors the code of issue request directly to unify the interface
and make the code clearer and more readable.

The 1st patch refactors the code of issue request directly to unify the
helper interface which could handle all the cases.

The 2nd patch make blk_mq_sched_insert_requests issue requests directly
with 'bypass' false, then it needn't to handle the non-issued requests
any more.

The 3rd patch replace and kill the blk_mq_request_issue_directly.

V8:
 - drop the original 2nd patch which try to insert requests into hctx->dispatch
   if quiesced or stopped.
 - remove two wrong 'unlikely'

V7:
 - drop the original 3rd patch which try to ensure hctx to be ran on
   its mapped cpu in issueing directly path.

V6:
 - drop original 1st patch to address Jen's comment
 - discard the enum mq_issue_decision and blk_mq_make_decision and use
   BLK_STS_* return values directly to address Jen's comment. (1/5)
 - add 'unlikely' in blk_mq_try_issue_directly (1/5)
 - refactor the 2nd and 3rd patch based on the new 1st patch.
 - reserve the unused_cookie in 4th and 5th patch

V5:
 - rebase against Jens' for-4.21/block branch
 - adjust the order of patch04 and patch05
 - add patch06 to replace and kill the one line blk_mq_request_bypass_insert
 - comment changes

V4:
 - split the original patch 1 into two patches, 1st and 2nd patch currently
 - rename the mq_decision to mq_issue_decision
 - comment changes

V3:
 - Correct the code about the case bypass_insert is true and io scheduler
   attached. The request still need to be issued in case above. (1/4)
 - Refactor the code to make code clearer. blk_mq_make_request is introduced
   to decide insert, end or just return based on the return value of .queue_rq
   and bypass_insert (1/4) 
 - Add the 2nd patch. It introduce a new decision result which indicates to
   insert request with blk_mq_request_bypass_insert.
 - Modify the code to adapt the new patch 1.

V2:
 - Add 1st and 2nd patch to refactor the code.

Jianchao Wang(3)
  blk-mq: refactor the code of issue request directly
  blk-mq: issue directly with bypass 'false' in blk_mq_sched_insert_requests
  blk-mq: replace and kill blk_mq_request_issue_directly

block/blk-core.c     |   4 +-
block/blk-mq-sched.c |   8 ++--
block/blk-mq.c       | 103 +++++++++++++++++++++------------------------------
block/blk-mq.h       |   7 ++--
4 files changed, 53 insertions(+), 69 deletions(-)

Thanks
Jianchao

Comments

Jens Axboe Dec. 5, 2018, 2:58 a.m. UTC | #1

On 11/14/18 8:12 PM, Jianchao Wang wrote:
> Hi Jens
> 
> Please consider this patchset for 4.21.
> It refactors the code of issue request directly to unify the interface
> and make the code clearer and more readable.
> 
> The 1st patch refactors the code of issue request directly to unify the
> helper interface which could handle all the cases.
> 
> The 2nd patch make blk_mq_sched_insert_requests issue requests directly
> with 'bypass' false, then it needn't to handle the non-issued requests
> any more.
> 
> The 3rd patch replace and kill the blk_mq_request_issue_directly.

I'd love to get this queued up, the direct dispatch path is a mess and
it's even now been known to cause corruptions... I'm going to queue
up the direct dispatch fix shortly, and apply it to for-4.21/block
as well. Any chance you can respin this on top after that?

jianchao.wang Dec. 5, 2018, 3:01 a.m. UTC | #2

On 12/5/18 10:58 AM, Jens Axboe wrote:
> On 11/14/18 8:12 PM, Jianchao Wang wrote:
>> Hi Jens
>>
>> Please consider this patchset for 4.21.
>> It refactors the code of issue request directly to unify the interface
>> and make the code clearer and more readable.
>>
>> The 1st patch refactors the code of issue request directly to unify the
>> helper interface which could handle all the cases.
>>
>> The 2nd patch make blk_mq_sched_insert_requests issue requests directly
>> with 'bypass' false, then it needn't to handle the non-issued requests
>> any more.
>>
>> The 3rd patch replace and kill the blk_mq_request_issue_directly.
> 
> I'd love to get this queued up, the direct dispatch path is a mess and
> it's even now been known to cause corruptions... I'm going to queue
> up the direct dispatch fix shortly, and apply it to for-4.21/block
> as well. Any chance you can respin this on top after that?
> 

OK, I will do now.

Thanks
Jianchao

Jens Axboe Dec. 5, 2018, 3:07 a.m. UTC | #3

On 12/4/18 8:01 PM, jianchao.wang wrote:
> 
> 
> On 12/5/18 10:58 AM, Jens Axboe wrote:
>> On 11/14/18 8:12 PM, Jianchao Wang wrote:
>>> Hi Jens
>>>
>>> Please consider this patchset for 4.21.
>>> It refactors the code of issue request directly to unify the interface
>>> and make the code clearer and more readable.
>>>
>>> The 1st patch refactors the code of issue request directly to unify the
>>> helper interface which could handle all the cases.
>>>
>>> The 2nd patch make blk_mq_sched_insert_requests issue requests directly
>>> with 'bypass' false, then it needn't to handle the non-issued requests
>>> any more.
>>>
>>> The 3rd patch replace and kill the blk_mq_request_issue_directly.
>>
>> I'd love to get this queued up, the direct dispatch path is a mess and
>> it's even now been known to cause corruptions... I'm going to queue
>> up the direct dispatch fix shortly, and apply it to for-4.21/block
>> as well. Any chance you can respin this on top after that?
>>
> 
> OK, I will do now.

Thanks!