From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <ming.lei@redhat.com>
Cc: Ming Lei <tom.leiming@gmail.com>,
Eric Biggers <ebiggers@kernel.org>,
"open list:AIO" <linux-aio@kvack.org>,
linux-block <linux-block@vger.kernel.org>,
linux-api@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
Jeff Moyer <jmoyer@redhat.com>, Avi Kivity <avi@scylladb.com>,
jannh@google.com, Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH 11/19] block: implement bio helper to add iter bvec pages to bio
Date: Tue, 26 Feb 2019 19:03:39 -0700 [thread overview]
Message-ID: <92ec262e-64ce-052b-11e2-dcc0f656be16@kernel.dk> (raw)
In-Reply-To: <e4dace7b-6a6f-2606-9a7e-8ae3c97c26b0@kernel.dk>
[-- Attachment #1: Type: text/plain, Size: 846 bytes --]
On 2/26/19 6:57 PM, Jens Axboe wrote:
> Speaking of this, I took a quick look at why we've now regressed a lot
> on IOPS perf with the multipage work. It looks like it's all related to
> the (much) fatter setup around iteration, which is related to this very
> topic too.
>
> Basically setup of things like bio_for_each_bvec() and indexing through
> nth_page() is MUCH slower than before.
>
> We need to do something about this, it's like tossing out months of
> optimizations.
See attached quick profile. This is doing 4k IOS, btw, so just single
segment requests. Yet we spend most of the time in blk_rq_map_sg(), and
blk_queue_split() is not far behind. Between just the two of them,
that's more than 8% of the total CPU utilization. As this test case is
running on just one CPU for all of it, that's a LOT of wasted time.
--
Jens Axboe
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next prev parent reply other threads:[~2019-02-27 2:03 UTC|newest]
Thread overview: 115+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-11 19:00 [PATCHSET v15] io_uring IO interface Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 01/19] fs: add an iopoll method to struct file_operations Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH] io_uring: add io_uring_event cache hit information Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 02/19] block: wire up block device iopoll method Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 03/19] block: add bio_set_polled() helper Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 04/19] iomap: wire up the iopoll method Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 05/19] Add io_uring IO interface Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 06/19] io_uring: add fsync support Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 07/19] io_uring: support for IO polling Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 08/19] fs: add fget_many() and fput_many() Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 09/19] io_uring: use fget/fput_many() for file references Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 10/19] io_uring: batch io_kiocb allocation Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 11/19] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-20 22:58 ` Ming Lei
2019-02-20 22:58 ` Ming Lei
2019-02-21 17:45 ` Jens Axboe
2019-02-21 17:45 ` Jens Axboe
2019-02-26 3:46 ` Eric Biggers
2019-02-26 3:46 ` Eric Biggers
2019-02-26 4:34 ` Jens Axboe
2019-02-26 4:34 ` Jens Axboe
2019-02-26 15:54 ` Jens Axboe
2019-02-26 15:54 ` Jens Axboe
2019-02-27 1:21 ` Ming Lei
2019-02-27 1:21 ` Ming Lei
2019-02-27 1:47 ` Jens Axboe
2019-02-27 1:47 ` Jens Axboe
2019-02-27 1:53 ` Ming Lei
2019-02-27 1:53 ` Ming Lei
2019-02-27 1:57 ` Jens Axboe
2019-02-27 1:57 ` Jens Axboe
2019-02-27 2:03 ` Jens Axboe [this message]
2019-02-27 2:21 ` Ming Lei
2019-02-27 2:21 ` Ming Lei
2019-02-27 2:28 ` Jens Axboe
2019-02-27 2:28 ` Jens Axboe
2019-02-27 2:37 ` Ming Lei
2019-02-27 2:37 ` Ming Lei
2019-02-27 2:43 ` Jens Axboe
2019-02-27 2:43 ` Jens Axboe
2019-02-27 3:09 ` Ming Lei
2019-02-27 3:09 ` Ming Lei
2019-02-27 3:37 ` Jens Axboe
2019-02-27 3:37 ` Jens Axboe
2019-02-27 3:43 ` Jens Axboe
2019-02-27 3:43 ` Jens Axboe
2019-02-27 3:44 ` Ming Lei
2019-02-27 3:44 ` Ming Lei
2019-02-27 4:05 ` Jens Axboe
2019-02-27 4:05 ` Jens Axboe
2019-02-27 4:06 ` Jens Axboe
2019-02-27 4:06 ` Jens Axboe
2019-02-27 19:42 ` Christoph Hellwig
2019-02-27 19:42 ` Christoph Hellwig
2019-02-28 8:37 ` Ming Lei
2019-02-28 8:37 ` Ming Lei
2019-02-27 23:35 ` Ming Lei
2019-02-27 23:35 ` Ming Lei
2019-03-08 7:55 ` Christoph Hellwig
2019-03-08 7:55 ` Christoph Hellwig
2019-03-08 9:12 ` Ming Lei
2019-03-08 9:12 ` Ming Lei
2019-03-08 8:18 ` Christoph Hellwig
2019-03-08 8:18 ` Christoph Hellwig
2019-02-11 19:00 ` [PATCH 12/19] io_uring: add support for pre-mapped user IO buffers Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-19 19:08 ` Jann Horn
2019-02-19 19:08 ` Jann Horn
2019-02-22 22:29 ` Jens Axboe
2019-02-22 22:29 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 13/19] net: split out functions related to registering inflight socket files Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 14/19] io_uring: add file set registration Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-19 16:12 ` Jann Horn
2019-02-19 16:12 ` Jann Horn
2019-02-22 22:29 ` Jens Axboe
2019-02-22 22:29 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 15/19] io_uring: add submission polling Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 16/19] io_uring: add io_kiocb ref count Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 17/19] io_uring: add support for IORING_OP_POLL Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 18/19] io_uring: allow workqueue item to handle multiple buffered requests Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-11 19:00 ` [PATCH 19/19] io_uring: add io_uring_event cache hit information Jens Axboe
2019-02-11 19:00 ` Jens Axboe
2019-02-21 12:10 ` [PATCHSET v15] io_uring IO interface Marek Majkowski
2019-02-21 12:10 ` Marek Majkowski
2019-02-21 17:48 ` Jens Axboe
2019-02-21 17:48 ` Jens Axboe
2019-02-22 15:01 ` Marek Majkowski
2019-02-22 15:01 ` Marek Majkowski
2019-02-22 22:32 ` Jens Axboe
2019-02-22 22:32 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2019-02-09 21:13 [PATCHSET v14] " Jens Axboe
2019-02-09 21:13 ` [PATCH 11/19] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2019-02-09 21:13 ` Jens Axboe
2019-02-08 17:34 [PATCHSET v13] io_uring IO interface Jens Axboe
2019-02-08 17:34 ` [PATCH 11/19] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2019-02-08 17:34 ` Jens Axboe
2019-02-09 9:45 ` Hannes Reinecke
2019-02-09 9:45 ` Hannes Reinecke
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