Re: [RFC 00/11] io_uring specific task_work infra

[Hao Xu <haoxu.linux@gmail.com>]

Hi,
在 2022/4/21 下午10:50, Pavel Begunkov 写道:
> On 4/21/22 14:44, Pavel Begunkov wrote:
>> For experiments only. If proves to be useful would need to make it
>> nicer on the non-io_uring side.
>>
>> 0-10 save 1 spinlock/unlock_irq pair and 2 cmpxchg per batch. 11/11 in
>> general trades 1 per tw add spin_lock/unlock_irq and 2 per batch 
>> spinlocking
>> with 2 cmpxchg to 1 per tw add cmpxchg and 1 per batch cmpxchg.
> 
> null_blk irqmode=1 completion_nsec=0 submit_queues=32 poll_queues=32
> echo -n 0 > /sys/block/nullb0/queue/iostats
> echo -n 2 > /sys/block/nullb0/queue/nomerges
> io_uring -d<QD> -s<QD> -c<QD> -p0 -B1 -F1 -b512 /dev/nullb0
This series looks good to me, by the way, what does -s and -c mean? and
what is the tested workload?

Regards,
Hao
> 
> 
>       | base | 1-10         | 1-11
> ___________________________________________
> QD1  | 1.88 | 2.15 (+14%)  | 2.19 (+16.4%)
> QD4  | 2.8  | 3.06 (+9.2%) | 3.11 (+11%)
> QD32 | 3.61 | 3.81 (+5.5%) | 3.96 (+9.6%)
> 
> The numbers are in MIOPS, (%) is relative diff with the baseline.
> It gives more than I expected, but the testing is not super
> consistent, so a part of it might be due to variance.
> 
> 
>> Pavel Begunkov (11):
>>    io_uring: optimise io_req_task_work_add
>>    io_uringg: add io_should_fail_tw() helper
>>    io_uring: ban tw queue for exiting processes
>>    io_uring: don't take ctx refs in tctx_task_work()
>>    io_uring: add dummy io_uring_task_work_run()
>>    task_work: add helper for signalling a task
>>    io_uring: run io_uring task_works on TIF_NOTIFY_SIGNAL
>>    io_uring: wire io_uring specific task work
>>    io_uring: refactor io_run_task_work()
>>    io_uring: remove priority tw list
>>    io_uring: lock-free task_work stack
>>
>>   fs/io-wq.c                |   1 +
>>   fs/io_uring.c             | 213 +++++++++++++++-----------------------
>>   include/linux/io_uring.h  |   4 +
>>   include/linux/task_work.h |   4 +
>>   kernel/entry/kvm.c        |   1 +
>>   kernel/signal.c           |   2 +
>>   kernel/task_work.c        |  33 +++---
>>   7 files changed, 115 insertions(+), 143 deletions(-)
>>
>