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From: Jens Axboe <[email protected]>
To: Pavel Begunkov <[email protected]>, [email protected]
Subject: Re: [RFC 0/4] completion locking optimisation feature
Date: Fri, 18 Mar 2022 08:52:05 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 3/18/22 8:42 AM, Pavel Begunkov wrote:
> On 3/18/22 13:52, Pavel Begunkov wrote:
>> A WIP feature optimising out CQEs posting spinlocking for some use cases.
>> For a more detailed description see 4/4.
>>
>> Quick benchmarking with fio/t/io_uring nops gives extra 4% to throughput for
>> QD=1, and ~+2.5% for QD=4.
> 
> Non-io_uring overhead (syscalls + userspace) takes ~60% of all execution
> time, so the percentage should quite depend on the CPU and the kernel config.
> Likely to be more than 4% for a faster setup.
> 
> fwiw, was also usingIORING_ENTER_REGISTERED_RING, if it's not yet included
> in the upstream version of the tool.

But that seems to be exclusive of using PRIVATE_CQ?

> Also, want to play after to see if we can also avoid taking uring_lock.

That would certainly also be interesting!


-- 
Jens Axboe


  reply	other threads:[~2022-03-18 14:52 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-18 13:52 [RFC 0/4] completion locking optimisation feature Pavel Begunkov
2022-03-18 13:52 ` [PATCH 1/4] io_uring: get rid of raw fill cqe in kill_timeout Pavel Begunkov
2022-03-18 13:52 ` [PATCH 2/4] io_uring: get rid of raw fill_cqe in io_fail_links Pavel Begunkov
2022-03-18 13:52 ` [PATCH 3/4] io_uring: remove raw fill_cqe from linked timeout Pavel Begunkov
2022-03-18 13:52 ` [PATCH 4/4] io_uring: optimise compl locking for non-shared rings Pavel Begunkov
2022-03-18 14:54   ` Jens Axboe
2022-03-18 15:13     ` Pavel Begunkov
2022-03-18 15:21       ` Jens Axboe
2022-03-18 15:32         ` Pavel Begunkov
2022-03-18 16:06           ` Jens Axboe
2022-03-18 14:42 ` [RFC 0/4] completion locking optimisation feature Pavel Begunkov
2022-03-18 14:52   ` Jens Axboe [this message]
2022-03-18 15:00     ` Pavel Begunkov
2022-03-18 15:22       ` Jens Axboe
2022-03-18 15:34         ` Pavel Begunkov

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