Re: [PATCH V3 0/9] io_uring: support sqe group and provide group kbuf

[Pavel Begunkov <asml.silence@gmail.com>]

On 6/3/24 01:05, Ming Lei wrote:
> On Sat, May 11, 2024 at 08:12:03AM +0800, Ming Lei wrote:
>> Hello,
>>
>> The 1st 4 patches are cleanup, and prepare for adding sqe group.
>>
>> The 5th patch supports generic sqe group which is like link chain, but
>> allows each sqe in group to be issued in parallel and the group shares
>> same IO_LINK & IO_DRAIN boundary, so N:M dependency can be supported with
>> sqe group & io link together. sqe group changes nothing on
>> IOSQE_IO_LINK.
>>
>> The 6th patch supports one variant of sqe group: allow members to depend
>> on group leader, so that kernel resource lifetime can be aligned with
>> group leader or group, then any kernel resource can be shared in this
>> sqe group, and can be used in generic device zero copy.
>>
>> The 7th & 8th patches supports providing sqe group buffer via the sqe
>> group variant.
>>
>> The 9th patch supports ublk zero copy based on io_uring providing sqe
>> group buffer.
>>
>> Tests:
>>
>> 1) pass liburing test
>> - make runtests
>>
>> 2) write/pass two sqe group test cases:
>>
>> https://github.com/axboe/liburing/compare/master...ming1:liburing:sqe_group_v2
>>
>> - covers related sqe flags combination and linking groups, both nop and
>> one multi-destination file copy.
>>
>> - cover failure handling test: fail leader IO or member IO in both single
>>    group and linked groups, which is done in each sqe flags combination
>>    test
>>
>> 3) ublksrv zero copy:
>>
>> ublksrv userspace implements zero copy by sqe group & provide group
>> kbuf:
>>
>> 	git clone https://github.com/ublk-org/ublksrv.git -b group-provide-buf_v2
>> 	make test T=loop/009:nbd/061:nbd/062	#ublk zc tests
>>
>> When running 64KB block size test on ublk-loop('ublk add -t loop --buffered_io -f $backing'),
>> it is observed that perf is doubled.
>>
>> Any comments are welcome!
>>
>> V3:
>> 	- add IORING_FEAT_SQE_GROUP
>> 	- simplify group completion, and minimize change on io_req_complete_defer()
>> 	- simplify & cleanup io_queue_group_members()
>> 	- fix many failure handling issues
>> 	- cover failure handling code in added liburing tests
>> 	- remove RFC
> 
> Hello Jens and Pavel,
> 
> V3 should address all your comments, would you mind to take a look at
> this version?

I'll take a look this weekend

-- 
Pavel Begunkov