From: Jens Axboe <axboe@kernel.dk>
To: Peter Zijlstra <peterz@infradead.org>,
Nitesh Shetty <nj.shetty@samsung.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
viro@zeniv.linux.org.uk, linux-block@vger.kernel.org,
linux-nvme@lists.infradead.org, joshi.k@samsung.com
Subject: Re: [PATCH] blk: optimization for classic polling
Date: Tue, 20 Feb 2018 12:37:07 -1000 [thread overview]
Message-ID: <35a2d52e-dd40-d130-85d9-5f3ffe0d28af@kernel.dk> (raw)
In-Reply-To: <20180220132137.GG25314@hirez.programming.kicks-ass.net>
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
next prev 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] <CGME20180208143655epcas1p444bf34705526b7839a5a135f82761aad@epcas1p4.samsung.com>
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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