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From: Alan Stern <stern@rowland.harvard.edu>
To: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Andrea Vai <andrea.vai@unipv.it>, Jens Axboe <axboe@kernel.dk>,
	<linux-usb@vger.kernel.org>, <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>
Subject: Re: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6
Date: Wed, 3 Jul 2019 10:23:13 -0400 (EDT)
Message-ID: <Pine.LNX.4.44L0.1907031020220.1547-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <20190703072934.GA4026@x250.microfocus.com>

On Wed, 3 Jul 2019, Johannes Thumshirn wrote:

> On Wed, Jul 03, 2019 at 12:36:30AM +0200, Andrea Vai wrote:
> > On 02/07/19 13:51:17, Johannes Thumshirn wrote:
> > > On Tue, Jul 02, 2019 at 12:46:45PM +0200, Andrea Vai wrote:
> > > > Hi,
> > > >   I have a problem writing data to a USB pendrive, and it seems
> > > > kernel-related. With the help of Greg an Alan (thanks) and some
> > > > bisect, I found out the offending commit being
> > > > 
> > > > commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6
> > > >
> > > > [...]
> > > 
> > > Hi,
> > > 
> > > Can you please check what IO scheduler you have set for your USB pendrive?
> > > 
> > > i.e. with:
> > > cat /sys/block/$DISK/queue/scheduler
> > >
> > 
> > # cat /sys/block/sdf/queue/scheduler
> > [mq-deadline] none
> 
> One thing you can try as well is building a kernel with CONFIG_IOSCHED_BFQ and
> use it. Deadline is probably not the best choice for a slow drive.

Andrea, another thing you could try is to collect a usbmon trace under 
one of the "slow" kernels.  Follow the instructions in 
Documentation/usb/usbmon.txt.  I think you could kill the file-copy 
operation after just a couple of seconds; that should provide enough 
trace information to help see what causes the slowdown.

(If you want, do the same test with a "fast" kernel and then we'll 
compare the results.)

Alan Stern


  reply index

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
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 [this message]
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
     [not found] <e3f87757f7a0fdf551e911ad32fc8122eebe04c7.camel@unipv.it>
2019-08-13 19:52 ` Alan Stern
     [not found] <307581a490b610c3025ee80f79a465a89d68ed19.camel@unipv.it>
2019-08-20 17:13 ` 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
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

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