From: Peter Zijlstra <peterz@infradead.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: Nitesh Shetty <nj.shetty@samsung.com>,
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: Wed, 21 Feb 2018 09:32:09 +0100 [thread overview]
Message-ID: <20180221083208.GH25314@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <35a2d52e-dd40-d130-85d9-5f3ffe0d28af@kernel.dk>
On Tue, Feb 20, 2018 at 12:37:07PM -1000, Jens Axboe wrote:
> 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.
Being ever more forgetful (I blame the kids) I find Changelogs more and
more important, ymmv ;-)
> > 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.
Right missed that. In fact, possibly the only reason I saw this is that
Nitesh had this computer configured wrong and the email is from the
future and thus the very first entry in my lkml folder.
next prev parent reply other threads:[~2018-02-21 8:32 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
2018-02-21 8:32 ` Peter Zijlstra [this message]
2018-10-10 18:52 ` Florian Fainelli
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