On Tue, 30 Sep 2014 14:10:28 +0800
"Lu, Baolu" <baolu.lu@xxxxxxxxxxxxxxx> wrote:
> On 9/30/2014 5:03 AM, Mark Knibbs wrote:
> > Great. I hope someone else is motivated to reproduce the issue. It will
> > take a long time for me to bisect due to my slow computer.
> Hi Mark,
>
> I tried to reproduce this issue. I connected a USB key under a
> full-speed hub.
Just to confirm, I do see the slowdown with a USB 2.0 drive connected to
USB 1.1 hub connected to USB 3.0 port. My results (kernel 3.17-rc6):
Connected to USB 3.0 port via USB 1.1 hub:
# ddpt if=/dev/sg6 bs=512 bpt=240 count=65536 verbose=2
>> Input file type: pass-through [pt] device
open /dev/sg6 with flags=0x802
inquiry cdb: 12 00 00 00 24 00
/dev/sg6: Freecom DataBar USB2.0 2.00 [pdt=0]
>> Output file type: null device
read capacity (10) cdb: 25 00 00 00 00 00 00 00 00 00
/dev/sg6 [readcap]: num_blocks=127908 [0x1f3a4], block_size=512, 65 MB
skip=0 (blocks on input), seek=0 (blocks on output)
ibs=512 bytes, obs=512 bytes, OBPC=0
initial count=65536 (blocks of input), blocks_per_transfer=240
Output file not specified so no copy, just reading input
65536+0 records in
0+0 records out
time to read data: 58.147836 secs at 577.1 KB/sec
Connected to USB 2.0 port via USB 1.1 hub:
# ddpt if=/dev/sg6 bs=512 bpt=240 count=65536 verbose=2
>> Input file type: pass-through [pt] device
open /dev/sg6 with flags=0x802
inquiry cdb: 12 00 00 00 24 00
/dev/sg6: Freecom DataBar USB2.0 2.00 [pdt=0]
>> Output file type: null device
read capacity (10) cdb: 25 00 00 00 00 00 00 00 00 00
/dev/sg6 [readcap]: num_blocks=127908 [0x1f3a4], block_size=512, 65 MB
skip=0 (blocks on input), seek=0 (blocks on output)
ibs=512 bytes, obs=512 bytes, OBPC=0
initial count=65536 (blocks of input), blocks_per_transfer=240
Output file not specified so no copy, just reading input
65536+0 records in
0+0 records out
time to read data: 39.146843 secs at 857.1 KB/sec
Mark
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