From: Jens Axboe <axboe@fb.com>
To: <axboe@kernel.dk>, <linux-kernel@vger.kernel.org>,
<linux-block@vger.kernel.org>
Cc: <hch@lst.de>
Subject: [PATCHSET v2] block: IO polling improvements
Date: Thu, 3 Nov 2016 13:45:02 -0600 [thread overview]
Message-ID: <1478202307-1947-1-git-send-email-axboe@fb.com> (raw)
Fixed a few bugs in this, and addressed some review comments. Patches
are against my 4.10 block branch, for-4.10/block.
Some performance results, running random reads against a fast device,
using either IRQ driven completions, classic polled, or the new hybrid
polled:
Method IOPS CPU% IOPS/CPU%
=========================================================
IRQ 476K 48.45% 9843
Poll 897K 99.9% 8982
Hybrid 836K 68.1% 12273
Classic polling is still a bit faster, but is uses a lot more CPU. The
rightmost column is an efficiency metric, and with the new hybrid
scheme, we're both faster and more efficient than IRQ driven. We should
be able to close the speed gap as well, so you can have your cake and
eat it too.
I've adjusted the default, so that classic polling is the default poll
method. To enable hybrid polling for a device, you would do:
# echo 0 > /sys/block/<dev>/queue/io_poll_delay
Also see the last patch for the other values this can be set to.
next reply other threads:[~2016-11-03 19:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-03 19:45 Jens Axboe [this message]
2016-11-03 19:45 ` [PATCH 1/5] block: fast-path for small and simple direct I/O requests Jens Axboe
2016-11-03 19:45 ` [PATCH 2/5] block: add scalable completion tracking of requests Jens Axboe
2016-11-03 19:45 ` [PATCH 3/5] block: move poll code to blk-mq Jens Axboe
2016-11-04 14:44 ` Christoph Hellwig
2016-11-04 15:30 ` Jens Axboe
2016-11-03 19:45 ` [PATCH 4/5] blk-mq: implement hybrid poll mode for sync O_DIRECT Jens Axboe
2016-11-03 19:45 ` [PATCH 5/5] blk-mq: make the polling code adaptive Jens Axboe
2016-11-07 15:28 [PATCHSET v2] block: IO polling improvements Stephen Bates
2016-11-07 15:29 ` Jens Axboe
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