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

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Date:   Tue, 17 Dec 2019 17:02:57 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Pavel Begunkov <asml.silence@...il.com>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] io_uring: batch getting pcpu references

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!

-- 
Jens Axboe