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From: Jens Axboe <>
To: Peter Zijlstra <>,
	Nitesh Shetty <>
Subject: Re: [PATCH] blk: optimization for classic polling
Date: Tue, 20 Feb 2018 12:37:07 -1000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 2/20/18 3:21 AM, Peter Zijlstra wrote:
> On Sun, May 30, 2083 at 09:51:06AM +0530, Nitesh Shetty wrote:
>> This removes the dependency on interrupts to wake up task. Set task
>> state as TASK_RUNNING, if need_resched() returns true,
>> while polling for IO completion.
>> Earlier, polling task used to sleep, relying on interrupt to wake it up.
>> This made some IO take very long when interrupt-coalescing is enabled in
>> NVMe.
> This is a horrible Changelog.. it does not in fact explain why the patch
> works or is correct.

Yeah, that should have been improved.

> Also, set_current_state(TASK_RUNNING) is dodgy (similarly in
> __blk_mq_poll), why do you need that memory barrier?

I pointed that out in the review, and v2 fixed it. v2 is the
one that got merged.

Jens Axboe

  parent reply	other threads:[~2018-02-20 22:37 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
2083-05-30  4:21 ` [PATCH] blk: optimization for classic polling Nitesh Shetty
2018-02-08 15:27   ` Keith Busch
2018-02-08 16:03     ` Sagi Grimberg
2018-02-12 15:50   ` Bart Van Assche
2018-02-20 13:21   ` Peter Zijlstra
2018-02-20 16:27     ` Keith Busch
2018-02-20 22:37     ` Jens Axboe [this message]
2018-02-21  8:32       ` Peter Zijlstra
2018-10-10 18:52   ` Florian Fainelli

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