Re: [PATCH 2/2] io_uring: batch getting pcpu references

Pavel Begunkov
2019-12-18T10:41:20Z

On 12/18/2019 3:02 AM, Jens Axboe wrote:
> On 12/17/19 3:28 PM, Pavel Begunkov wrote:
>> percpu_ref_tryget() has its own overhead. Instead getting a reference
>> for each request, grab a bunch once per io_submit_sqes().
>>
>> basic benchmark with submit and wait 128 non-linked nops showed ~5%
>> performance gain. (7044 KIOPS vs 7423)
>
> Confirmed about 5% here as well, doing polled IO to a fast device.
> That's a huge gain!
>
Great that you got it for a real drive!
As mentioned, after we are done with this one, I have an idea how to
optimise it even further, which would work for small QD as well.

--
Pavel Begunkov