Re: [PATCH v7 1/2] io_uring: avoid whole io_wq_work copy for requests completed inline

[Jens Axboe <axboe@kernel.dk>]

On 6/10/20 5:41 AM, Xiaoguang Wang wrote:
> If requests can be submitted and completed inline, we don't need to
> initialize whole io_wq_work in io_init_req(), which is an expensive
> operation, add a new 'REQ_F_WORK_INITIALIZED' to determine whether
> io_wq_work is initialized and add a helper io_req_init_async(), users
> must call io_req_init_async() for the first time touching any members
> of io_wq_work.
> 
> I use /dev/nullb0 to evaluate performance improvement in my physical
> machine:
>   modprobe null_blk nr_devices=1 completion_nsec=0
>   sudo taskset -c 60 fio  -name=fiotest -filename=/dev/nullb0 -iodepth=128
>   -thread -rw=read -ioengine=io_uring -direct=1 -bs=4k -size=100G -numjobs=1
>   -time_based -runtime=120
> 
> before this patch:
> Run status group 0 (all jobs):
>    READ: bw=724MiB/s (759MB/s), 724MiB/s-724MiB/s (759MB/s-759MB/s),
>    io=84.8GiB (91.1GB), run=120001-120001msec
> 
> With this patch:
> Run status group 0 (all jobs):
>    READ: bw=761MiB/s (798MB/s), 761MiB/s-761MiB/s (798MB/s-798MB/s),
>    io=89.2GiB (95.8GB), run=120001-120001msec
> 
> About 5% improvement.

Thanks for pulling this one to completion! I've applied 1-2 for 5.8.

One note on future patches only - please use a coverletter, makes
it easier to reply to the series as a whole.

-- 
Jens Axboe