On Sun, Dec 27, 2009 at 1:57 PM, Paul Hartman <[email protected]> wrote: > On Sun, Dec 27, 2009 at 1:46 PM, Paul Hartman > <[email protected]> wrote: >> On Sun, Dec 27, 2009 at 12:10 PM, Paul Hartman >> <[email protected]> wrote: >>> On Sun, Dec 27, 2009 at 12:01 AM, Michael Holmes >>> <[email protected]> wrote: >>>> 2009/12/27 Paul Hartman <[email protected]>: >>>>> On Sat, Dec 26, 2009 at 7:00 PM, Hung Dang <[email protected]> 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!
