Linux-USB Archive on lore.kernel.org
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From: Andrea Vai <andrea.vai@unipv.it>
To: Ming Lei <ming.lei@redhat.com>
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 08:46:07 +0100
Message-ID: <0598fe2754bf0717d81f7e72d3e9b3230c608cc6.camel@unipv.it> (raw)
In-Reply-To: <20191126023253.GA24501@ming.t460p>

[-- Attachment #1: Type: text/plain, Size: 2944 bytes --]

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).

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.

>  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.


> 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)).

Thanks,
Andrea

[1]: http://fisica.unipv.it/transfer/kernelstats.zip

[-- Attachment #2: git_diff.txt --]
[-- Type: text/plain, Size: 6424 bytes --]

# git diff
diff --git a/block/blk-mq.c b/block/blk-mq.c
index ec791156e9cc..92d60a5e1d15 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1465,7 +1465,13 @@ static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
        if (unlikely(blk_mq_hctx_stopped(hctx)))
                return;
 
-       if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
+       /*
+        * Some single-queue devices may need to dispatch IO in order
+        * which was guaranteed for the legacy queue via the big queue
+        * lock. Now we reply on single hctx->run_work for that.
+        */
+       if (!async && !(hctx->flags & (BLK_MQ_F_BLOCKING |
+                                       BLK_MQ_F_STRICT_DISPATCH_ORDER))) {
                int cpu = get_cpu();
                if (cpumask_test_cpu(cpu, hctx->cpumask)) {
                        __blk_mq_run_hw_queue(hctx);
@@ -3055,6 +3061,10 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
        if (!set->ops->get_budget ^ !set->ops->put_budget)
                return -EINVAL;
 
+       if (set->queue_depth > 1 && (set->flags &
+                               BLK_MQ_F_STRICT_DISPATCH_ORDER))
+               return -EINVAL;
+
        if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
                pr_info("blk-mq: reduced tag depth to %u\n",
                        BLK_MQ_MAX_DEPTH);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 91c007d26c1e..f013630275c9 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1902,6 +1902,9 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
        shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
        shost->tag_set.flags |=
                BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
+       if (shost->hostt->strict_dispatch_order)
+               shost->tag_set.flags |= BLK_MQ_F_STRICT_DISPATCH_ORDER;
+
        shost->tag_set.driver_data = shost;
 
        return blk_mq_alloc_tag_set(&shost->tag_set);
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 54a3c8195c96..df1674d7f0fc 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -651,6 +651,18 @@ static const struct scsi_host_template usb_stor_host_template = {
        /* we do our own delay after a device or bus reset */
        .skip_settle_delay =            1,
diff --git a/block/blk-mq.c b/block/blk-mq.c
index ec791156e9cc..92d60a5e1d15 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1465,7 +1465,13 @@ static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
        if (unlikely(blk_mq_hctx_stopped(hctx)))
                return;
 
-       if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
+       /*
+        * Some single-queue devices may need to dispatch IO in order
+        * which was guaranteed for the legacy queue via the big queue
+        * lock. Now we reply on single hctx->run_work for that.
+        */
+       if (!async && !(hctx->flags & (BLK_MQ_F_BLOCKING |
+                                       BLK_MQ_F_STRICT_DISPATCH_ORDER))) {
                int cpu = get_cpu();
                if (cpumask_test_cpu(cpu, hctx->cpumask)) {
                        __blk_mq_run_hw_queue(hctx);
@@ -3055,6 +3061,10 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
        if (!set->ops->get_budget ^ !set->ops->put_budget)
                return -EINVAL;
 
+       if (set->queue_depth > 1 && (set->flags &
+                               BLK_MQ_F_STRICT_DISPATCH_ORDER))
+               return -EINVAL;
+
        if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
                pr_info("blk-mq: reduced tag depth to %u\n",
                        BLK_MQ_MAX_DEPTH);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 91c007d26c1e..f013630275c9 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1902,6 +1902,9 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
        shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
        shost->tag_set.flags |=
                BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
+       if (shost->hostt->strict_dispatch_order)
+               shost->tag_set.flags |= BLK_MQ_F_STRICT_DISPATCH_ORDER;
+
        shost->tag_set.driver_data = shost;
 
        return blk_mq_alloc_tag_set(&shost->tag_set);
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 54a3c8195c96..df1674d7f0fc 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -651,6 +651,18 @@ static const struct scsi_host_template usb_stor_host_template = {
        /* we do our own delay after a device or bus reset */
        .skip_settle_delay =            1,
 
+
+       /*
+        * Some USB storage, such as Kingston Technology DataTraveler 100
+        * G3/G4/SE9 G2(ID 0951:1666), requires IO dispatched in the
+        * sequential order, otherwise IO performance may drop drastically.
+        *
+        * can_queue is always 1, so we set .strict_dispatch_order for
+        * USB mass storage HBA. Another reason is that there can be such
+        * kind of devices too.
+        */
+       .strict_dispatch_order =        1,
+
        /* sysfs device attributes */
        .sdev_attrs =                   sysfs_device_attr_list,
 
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 0bf056de5cc3..89b1c28da36a 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -226,6 +226,7 @@ struct blk_mq_ops {
 enum {
        BLK_MQ_F_SHOULD_MERGE   = 1 << 0,
        BLK_MQ_F_TAG_SHARED     = 1 << 1,
+       BLK_MQ_F_STRICT_DISPATCH_ORDER  = 1 << 2,
        BLK_MQ_F_BLOCKING       = 1 << 5,
        BLK_MQ_F_NO_SCHED       = 1 << 6,
        BLK_MQ_F_ALLOC_POLICY_START_BIT = 8,
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 31e0d6ca1eba..dbcbc9ef6993 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -442,6 +442,13 @@ struct scsi_host_template {
        /* True if the low-level driver supports blk-mq only */
        unsigned force_blk_mq:1;
 
+       /*
+        * True if the low-level driver needs IO to be dispatched in
+        * the order provided by legacy IO path. The flag is only
+        * valid for single queue device.
+        */
+       unsigned strict_dispatch_order:1;
+
        /*
         * Countdown for host blocking with no commands outstanding.
         */


  reply index

Thread overview: 120+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [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
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 [this message]
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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