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Subject: Re: [RFC 4/4] io_uring: implement futex wait
To:     Pavel Begunkov <asml.silence@gmail.com>, io-uring@vger.kernel.org
Cc:     Andres Freund <andres@anarazel.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Darren Hart <dvhart@infradead.org>,
        Davidlohr Bueso <dave@stgolabs.net>,
        linux-kernel@vger.kernel.org
References: <cover.1622558659.git.asml.silence@gmail.com>
 <e91af9d8f8d6e376635005fd111e9fe7a1c50fea.1622558659.git.asml.silence@gmail.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <bd824ec8-48af-b554-67a1-7ce20fcf608c@kernel.dk>
Date:   Tue, 1 Jun 2021 09:45:22 -0600
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On 6/1/21 8:58 AM, Pavel Begunkov wrote:
> Add futex wait requests, those always go through io-wq for simplicity.

Not a huge fan of that, I think this should tap into the waitqueue
instead and just rely on the wakeup callback to trigger the event. That
would be a lot more efficient than punting to io-wq, both in terms of
latency on trigger, but also for efficiency if the app is waiting on a
lot of futexes.

-- 
Jens Axboe