Re: [gentoo-user] USB mass storage device slow in Gentoo, fast in Windows...?

[Paul Hartman]

On Sun, Dec 27, 2009 at 1:57 PM, Paul Hartman
<paul.hartman+gentoo@×××××.com> wrote:
> On Sun, Dec 27, 2009 at 1:46 PM, Paul Hartman
> <paul.hartman+gentoo@×××××.com> wrote:
>> On Sun, Dec 27, 2009 at 12:10 PM, Paul Hartman
>> <paul.hartman+gentoo@×××××.com> wrote:
>>> On Sun, Dec 27, 2009 at 12:01 AM, Michael Holmes
>>> <holmesmich@××××××××××.com> wrote:
>>>> 2009/12/27 Paul Hartman <paul.hartman+gentoo@×××××.com>:
>>>>> On Sat, Dec 26, 2009 at 7:00 PM, Hung Dang <hungptit@×××××.com> wrote:
>>>>>> On 12/26/09 15:54, Paul Hartman wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> I got a Nokia N900 linux internet tablet/phone a few days ago, and
>>>>>>> when I connect it in USB Mass Storage mode to a Windows Vista computer
>>>>>>> I can write at 17MB/sec, but when I connect it to my Gentoo box my
>>>>>>> writes are really slow, between 500-900kb/sec depending on if I mount
>>>>>>> in "sync" mode or not. As far as I know it should be just a totally
>>>>>>> standard/generic mass storage device. (there were no drivers or
>>>>>>> software install needed in windows, it just worked)
>>>>>>>
>>>>>>> Other USB devices plugged into the same port go full speed, and AFAIK
>>>>>>> everything appears as if it should be high speed USB 2.0. Has anyone
>>>>>>> seen something like this before? I'm not sure what the deal is. It
>>>>>>> takes 20 minutes to copy 1 gigabyte from Linux and takes just under 1
>>>>>>> minute to do the same in Windows.
>>>>>>>
>>>>>>> I'm not sure about debugging USB or what the options are. Everything
>>>>>>> I've used previously has worked without any hassle.
>>>>>> Have you received a lot of debugging messages at the output of dmesg
>>>>>> when copying files?
>>>>>>
>>>>>> Hung
>>>>>
>>>>> No errors, no strange messages at all, it seems normal (only slow). I
>>>>> have other USB devices like SD card reader, external HDD, and they
>>>>> perform at full speed when plugged into the same port, so it's weird
>>>>> to me.
>>>>>
>>>>> Thanks
>>>>> Paul
>>>>>
>>>>>
>>>>
>>>> This isn't that helpful, but in Windows I get good thoroughputs in
>>>> mass storage mode, but compartively weak ones in sync mode. But this
>>>> shouldn't be the problem because as far as I know, there are no
>>>> ync-mode drivers for good old Linux (which is ironic if you consider
>>>> it).
>>>
>>> When I said "sync" mode I mean mounting the device in mass storage
>>> mode with with "-o sync" (as opposed to the default cached/async
>>> mode), which I believe is the default in Windows Vista & Win7 (because
>>> most windows users cannot be bothered to unmount before pulling the
>>> plug).
>>>
>>> Thanks
>>
>> Well, after a bit more plugging/unplugging of all my USB devices into
>> various ports in different orders, it seems to be going fast now. I
>> hate USB :)
>>
>> Thanks for the help
>
> Maybe I spoke too soon. It seems what's happening is when I write a
> large amount of data, there are several "pdflush" threads at near 100%
> i/o wait. I'm thinking it's writing multiple streams over USB which is
> causing the massive slow-down.
>
> I'm using 2.6.31, and I see in 2.6.32 there is something called
> "Per-backing-device based writeback" which may help me here... I'll
> try the new kernel and report back :)

There is a slight improvement but it's still very slow (less than
2MB/sec). It seems the problem happens if I try to copy more than 1
file to the device. If I copy/sync/copy/sync/copy/sync etc it goes
faster, but that's extremely annoying!