From: Alan Stern <stern@rowland.harvard.edu>
To: Damien Le Moal <Damien.LeMoal@wdc.com>
Cc: Andrea Vai <andrea.vai@unipv.it>,
Johannes Thumshirn <jthumshirn@suse.de>,
Jens Axboe <axboe@kernel.dk>,
USB list <linux-usb@vger.kernel.org>,
SCSI development list <linux-scsi@vger.kernel.org>,
Himanshu Madhani <himanshu.madhani@cavium.com>,
Hannes Reinecke <hare@suse.com>, Ming Lei <ming.lei@redhat.com>,
Omar Sandoval <osandov@fb.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Greg KH <gregkh@linuxfoundation.org>,
Hans Holmberg <Hans.Holmberg@wdc.com>
Subject: Re: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6
Date: Thu, 19 Sep 2019 10:01:01 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1909190958140.1585-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <BYAPR04MB58160E6FEBD92D04ECA7D303E7890@BYAPR04MB5816.namprd04.prod.outlook.com>
On Thu, 19 Sep 2019, Damien Le Moal wrote:
> > This is exactly the sort of difference one might expect to see from
> > the commit f664a3cc17b7 ("scsi: kill off the legacy IO path") you
> > identified as the cause of the problem. With multiqueue I/O, it's not
> > surprising to see multiple sequences of block numbers.
> >
> > Add it's not at all surprising that a consumer-grade USB storage device
> > might do a much worse job of handling non-sequential writes than
> > sequential ones.
> >
> > Which leads to a simple question for the SCSI or block-layer
> > maintainers: Is there a sysfs setting Andrea can tweak which will
> > effectively restrict a particular disk device down to a single I/O
> > queue, forcing sequential access?
>
> The scheduling inefficiency you are seeing may be coming from the fact that the
> block layer does a direct issue of requests, bypassing the elevator, under some
> conditions. One of these is sync requests on a multiqueue device. We hit this
> problem on Zoned disks which can easily return an error for write requests
> without the elevator throttling writes per zones (zone write locking). This
> problem was discovered by Hans (on CC).
Is there any way for Andrea to check whether this is the underlying
cause?
> I discussed this with Hannes yesterday and we think we have a fix, but we'll
> need to do a lot of testing as all block devices are potentially impacted by the
> change, including stacked drivers (DM). Performance regression is scary with any
> change in that area (see blk_mq_make_request() and use of
> blk_mq_try_issue_directly() vs blk_mq_sched_insert_request()).
No doubt Andrea will be happy to test your fix when it's ready.
Alan Stern
next prev parent reply other threads:[~2019-09-19 14:01 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <307581a490b610c3025ee80f79a465a89d68ed19.camel@unipv.it>
2019-08-20 17:13 ` Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6 Alan Stern
2019-08-23 10:39 ` Andrea Vai
2019-08-23 20:42 ` Alan Stern
2019-08-26 6:09 ` Andrea Vai
2019-08-26 16:33 ` Alan Stern
2019-09-18 15:25 ` Andrea Vai
2019-09-18 16:30 ` Alan Stern
2019-09-19 7:33 ` Andrea Vai
2019-09-19 17:54 ` Alan Stern
2019-09-20 7:25 ` Andrea Vai
2019-09-20 7:44 ` Greg KH
2019-09-19 8:26 ` Damien Le Moal
2019-09-19 8:55 ` Ming Lei
2019-09-19 9:09 ` Damien Le Moal
2019-09-19 9:21 ` Ming Lei
2019-09-19 14:01 ` Alan Stern [this message]
2019-09-19 14:14 ` Damien Le Moal
2019-09-20 7:03 ` Andrea Vai
2019-09-25 19:30 ` Alan Stern
2019-09-25 19:36 ` Jens Axboe
2019-09-27 15:47 ` Andrea Vai
2019-11-04 16:00 ` Andrea Vai
2019-11-04 18:20 ` Alan Stern
2019-11-05 11:48 ` Andrea Vai
2019-11-05 18:31 ` Alan Stern
2019-11-05 23:29 ` Jens Axboe
2019-11-06 16:03 ` Alan Stern
2019-11-06 22:13 ` Damien Le Moal
2019-11-07 7:04 ` Andrea Vai
2019-11-07 7:54 ` Damien Le Moal
2019-11-07 18:59 ` Andrea Vai
2019-11-08 8:42 ` Damien Le Moal
2019-11-08 14:33 ` Jens Axboe
2019-11-11 10:46 ` Andrea Vai
2019-11-09 10:09 ` Ming Lei
2019-11-09 22:28 ` Ming Lei
2019-11-11 10:50 ` Andrea Vai
2019-11-11 11:05 ` Ming Lei
2019-11-11 11:13 ` Andrea Vai
2019-11-22 19:16 ` Andrea Vai
2019-11-23 7:28 ` Ming Lei
2019-11-23 15:44 ` Andrea Vai
2019-11-25 3:54 ` Ming Lei
2019-11-25 10:11 ` Andrea Vai
2019-11-25 10:29 ` Ming Lei
2019-11-25 14:58 ` Andrea Vai
2019-11-25 15:15 ` Ming Lei
2019-11-25 18:51 ` Andrea Vai
2019-11-26 2:32 ` Ming Lei
2019-11-26 7:46 ` Andrea Vai
2019-11-26 9:15 ` Ming Lei
2019-11-26 10:24 ` Ming Lei
2019-11-26 11:14 ` Andrea Vai
2019-11-27 2:05 ` Ming Lei
2019-11-27 9:39 ` Andrea Vai
2019-11-27 13:08 ` Ming Lei
2019-11-27 15:01 ` Andrea Vai
2019-11-27 0:21 ` Finn Thain
2019-11-27 8:14 ` AW: " Schmid, Carsten
2019-11-27 21:49 ` Finn Thain
2019-11-28 7:46 ` Andrea Vai
2019-11-28 8:12 ` AW: " Schmid, Carsten
2019-11-28 11:40 ` Andrea Vai
2019-11-28 17:39 ` Alan Stern
2019-11-28 9:17 ` Ming Lei
2019-11-28 17:34 ` Andrea Vai
2019-11-29 0:57 ` Ming Lei
2019-11-29 2:35 ` Ming Lei
2019-11-29 14:41 ` Andrea Vai
2019-12-03 2:23 ` Ming Lei
2019-12-10 7:35 ` Andrea Vai
2019-12-10 8:05 ` Ming Lei
2019-12-11 2:41 ` Theodore Y. Ts'o
2019-12-11 4:00 ` Ming Lei
2019-12-11 16:07 ` Theodore Y. Ts'o
2019-12-11 21:33 ` Ming Lei
2019-12-12 7:34 ` Andrea Vai
2019-12-18 8:25 ` Andrea Vai
2019-12-18 9:48 ` Ming Lei
[not found] ` <b1b6a0e9d690ecd9432025acd2db4ac09f834040.camel@unipv.it>
2019-12-23 13:08 ` Ming Lei
2019-12-23 14:02 ` Andrea Vai
2019-12-24 1:32 ` Ming Lei
2019-12-24 8:04 ` Andrea Vai
2019-12-24 8:47 ` Ming Lei
2019-12-23 16:26 ` Theodore Y. Ts'o
2019-12-23 16:29 ` Andrea Vai
2019-12-23 17:22 ` Theodore Y. Ts'o
2019-12-23 18:45 ` Andrea Vai
2019-12-23 19:53 ` Theodore Y. Ts'o
2019-12-24 1:27 ` Ming Lei
2019-12-24 6:49 ` Andrea Vai
2019-12-24 8:51 ` Andrea Vai
2019-12-24 9:35 ` Ming Lei
2019-12-25 5:17 ` Theodore Y. Ts'o
2019-12-26 2:27 ` Ming Lei
2019-12-26 3:30 ` Theodore Y. Ts'o
2019-12-26 8:37 ` Ming Lei
2020-01-07 7:51 ` Andrea Vai
[not found] ` <20200101074310.10904-1-hdanton@sina.com>
2020-01-01 13:53 ` slow IO on USB media Ming Lei
2019-11-29 11:44 ` AW: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6 Bernd Schubert
2019-12-02 7:01 ` Andrea Vai
2019-11-28 17:10 ` Andrea Vai
[not found] <e3f87757f7a0fdf551e911ad32fc8122eebe04c7.camel@unipv.it>
2019-08-13 19:52 ` Alan Stern
2019-07-02 10:46 Andrea Vai
2019-07-02 11:51 ` Johannes Thumshirn
2019-07-02 22:36 ` Andrea Vai
2019-07-03 7:29 ` Johannes Thumshirn
2019-07-03 14:23 ` Alan Stern
2019-07-06 22:06 ` Andrea Vai
2019-07-08 15:38 ` Alan Stern
2019-07-02 12:01 ` Ming Lei
2019-07-02 22:39 ` Andrea Vai
2019-07-03 2:01 ` Ming Lei
2019-07-03 5:11 ` Andrea Vai
2019-07-03 6:36 ` Ming Lei
2019-07-03 15:27 ` Chris Murphy
2019-07-06 9:33 ` Andrea Vai
2019-07-08 1:01 ` Ming Lei
2019-07-09 21:18 ` Andrea Vai
2019-07-10 2:44 ` Ming Lei
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