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From: Ming Lei <ming.lei@redhat.com>
To: Andrea Vai <andrea.vai@unipv.it>
Cc: Damien Le Moal <Damien.LeMoal@wdc.com>,
	Alan Stern <stern@rowland.harvard.edu>,
	Jens Axboe <axboe@kernel.dk>,
	Johannes Thumshirn <jthumshirn@suse.de>,
	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>, Omar Sandoval <osandov@fb.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Hans Holmberg <Hans.Holmberg@wdc.com>,
	Kernel development list <linux-kernel@vger.kernel.org>
Subject: Re: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6
Date: Tue, 26 Nov 2019 17:15:33 +0800	[thread overview]
Message-ID: <20191126091533.GB32135@ming.t460p> (raw)
In-Reply-To: <0598fe2754bf0717d81f7e72d3e9b3230c608cc6.camel@unipv.it>

On Tue, Nov 26, 2019 at 08:46:07AM +0100, Andrea Vai wrote:
> Il giorno mar, 26/11/2019 alle 10.32 +0800, Ming Lei ha scritto:
> > On Mon, Nov 25, 2019 at 07:51:33PM +0100, Andrea Vai wrote:
> > > Il giorno lun, 25/11/2019 alle 23.15 +0800, Ming Lei ha scritto:
> > > > On Mon, Nov 25, 2019 at 03:58:34PM +0100, Andrea Vai wrote:
> > > > 
> > > > [...]
> > > > 
> > > > > What to try next?
> > > > 
> > > > 1) cat /sys/kernel/debug/block/$DISK/hctx0/flags
> > > result:
> > > 
> > > alloc_policy=FIFO SHOULD_MERGE|2
> > > 
> > > > 
> > > > 
> > > > 2) echo 128 > /sys/block/$DISK/queue/nr_requests and run your
> > copy
> > > > 1GB
> > > > test again.
> > > 
> > > done, and still fails. What to try next?
> > 
> > I just run 256M cp test
> 
> I would like to point out that 256MB is a filesize that usually don't
> trigger the issue (don't know if it matters, sorry).

OK.

I tested 256M because IO timeout is often triggered in case of
qemu-ehci, and it is a long-term issue. When setting up the disk
via xhci-qemu, the max request size is increased to 1MB from 120KB,
and IO pattern changed too. When the disk is connected via uhci-qemu,
the transfer is too slow(1MB/s) because max endpoint size is too small.

However, I just waited 16min and collected all the 1GB IO log by
connecting disk over uhci-qemu, but the sector of each data IO
is still in order.

> 
> Another info I would provide is about another strange behavior I
> noticed: yesterday I ran the test two times (as usual with 1GB
> filesize) and took 2370s, 1786s, and a third test was going on when I
> stopped it. Then I started another set of 100 trials and let them run
> tonight, and the first 10 trials were around 1000s, then gradually
> decreased to ~300s, and finally settled around 200s with some trials
> below 70-80s. This to say, times are extremely variable and for the
> first time I noticed a sort of "performance increase" with time.

The 'cp' test is buffered IO, can you reproduce it every time by
running copy just after fresh mount on the USB disk?

> 
> >  to one USB storage device on patched kernel,
> > and WRITE data IO is really in ascending order. The filesystem is
> > ext4,
> > and mount without '-o sync'. From previous discussion, looks that is
> > exactly your test setting. The order can be observed via the
> > following script:
> > 
> > #!/bin/sh
> > MAJ=$1
> > MIN=$2
> > MAJ=$(( $MAJ << 20 ))
> > DEV=$(( $MAJ | $MIN ))
> > /usr/share/bcc/tools/trace -t -C \
> >   't:block:block_rq_issue (args->dev == '$DEV') "%s %d %d", args-
> > >rwbs, args->sector, args->nr_sector'
> > 
> > $MAJ & $MIN can be retrieved via lsblk for your USB storage disk.
> > 
> > So I think we need to check if the patch is applied correctly first.
> > 
> > If your kernel tree is managed via git,
> yes it is,
> 
> >  please post 'git diff'.
> attached. Is it correctly patched? thanks.

Yeah, it should be correct except for the change on __blk_mq_delay_run_hw_queue()
is duplicated.

> 
> 
> > Otherwise, share us your kernel version,
> btw, is 5.4.0+
> 
> >  and I will send you one
> > backported patch on the kernel version.
> > 
> > Meantime, you can collect IO order log via the above script as you
> > did last
> > time, then send us the log.
> 
> ok, will try; is it just required to run it for a short period of time
> (say, some seconds) during the copy, or should I run it before the
> beginning (or before the mount?), and terminate it after the end of
> the copy? (Please note that in the latter case a large amount of time
> (and data, I suppose) would be involved, because, as said, to be sure
> the problem triggers I have to use a large file... but we can try to
> better understand and tune this. If it can help, you can get an ods
> file with the complete statistic at [1] (look at the "prove_nov19"
> sheet)).

The data won't be very big, each line covers 120KB, and ~10K line
is enough for cover 1GB transfer. Then ~300KB compressed file should
hold all the trace.


Thanks, 
Ming


  reply	other threads:[~2019-11-26  9:16 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
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 [this message]
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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