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From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@fb.com>
Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org,
	linux-block@vger.kernel.org, hch@lst.de
Subject: Re: [PATCH 3/4] blk-mq: implement hybrid poll mode for sync O_DIRECT
Date: Wed, 2 Nov 2016 15:54:59 +0100	[thread overview]
Message-ID: <20161102145459.GD13964@lst.de> (raw)
In-Reply-To: <1478034325-28232-4-git-send-email-axboe@fb.com>

On Tue, Nov 01, 2016 at 03:05:24PM -0600, Jens Axboe wrote:
> This patch enables a hybrid polling mode. Instead of polling after IO
> submission, we can induce an artificial delay, and then poll after that.
> For example, if the IO is presumed to complete in 8 usecs from now, we
> can sleep for 4 usecs, wake up, and then do our polling. This still puts
> a sleep/wakeup cycle in the IO path, but instead of the wakeup happening
> after the IO has completed, it'll happen before. With this hybrid
> scheme, we can achieve big latency reductions while still using the same
> (or less) amount of CPU.
> 
> Signed-off-by: Jens Axboe <axboe@fb.com>

This looks very nice.  I'll need to run some tests before giving the
formal ACK, though.

  reply	other threads:[~2016-11-02 14:55 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-01 21:05 [PATCHSET] block: IO polling improvements Jens Axboe
2016-11-01 21:05 ` [PATCH 1/4] block: add scalable completion tracking of requests Jens Axboe
2016-11-01 22:25   ` Johannes Thumshirn
2016-11-02  5:37     ` Jens Axboe
2016-11-02 14:52   ` Christoph Hellwig
2016-11-02 14:55     ` Jens Axboe
2016-11-02 14:59       ` Christoph Hellwig
2016-11-03 11:17   ` Ming Lei
2016-11-03 13:38     ` Jens Axboe
2016-11-03 14:57       ` Ming Lei
2016-11-03 16:55         ` Jens Axboe
2016-11-04 23:13           ` Ming Lei
2016-11-05 20:49             ` Jens Axboe
2016-11-05 20:59             ` Jens Axboe
2016-11-03 14:10   ` Bart Van Assche
2016-11-03 14:18     ` Jens Axboe
2016-11-01 21:05 ` [PATCH 2/4] block: move poll code to blk-mq Jens Axboe
2016-11-02 14:54   ` Christoph Hellwig
2016-11-01 21:05 ` [PATCH 3/4] blk-mq: implement hybrid poll mode for sync O_DIRECT Jens Axboe
2016-11-02 14:54   ` Christoph Hellwig [this message]
2016-11-03 12:27   ` Ming Lei
2016-11-03 13:41     ` Jens Axboe
2016-11-03 14:01   ` Bart Van Assche
2016-11-03 14:15     ` Jens Axboe
2016-11-01 21:05 ` [PATCH 4/4] blk-mq: make the polling code adaptive Jens Axboe
2016-11-02 14:51 ` [PATCHSET] block: IO polling improvements Christoph Hellwig
2016-11-02 14:54   ` Jens Axboe

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