[maemo-users] Slow writes from linux to N900 in USB Mass Storage Mode

From: Kimmo Hämäläinen kimmo.hamalainen at nokia.com
Date: Tue Jan 5 13:29:53 EET 2010

On Sun, 2009-12-27 at 22:38 +0100, ext Paul Hartman wrote:
> Hi,
> I'm using linux kernel 2.6.32 on my PC and mount N900 in mass storage
> mode using vfat (async).
> If I write one file then sync/umount, write speed is about 17MB/sec,
> same as I get on Windows Vista. However, if I write more than one file
> and then sync/umount, speed is terrible, around 2MB/sec (and in kernel
> 2.6.31 that speed was about 450kb/sec using the old pdflush code). So
> it seems linux is maybe creating multiple write streams and N900
> doesn't deal with that well at all.

There has been some USB speed-ups since the sales release, but I'm not
sure if they fix this multiple file copying problem. I think it's best
to file a bug to maemo.org, so Maemo kernel guys get the word (I think
too few of them read this mailing list).


> Size doesn't seem to matter, copying one 1gb file followed by sync is
> around 8 times faster than copying 2 500gb files followed by sync. In
> other words, as long as every single file copy is followed immediately
> by sync before moving on to the next file, speed is fine. If more than
> 1 file is copied before sync, it's bad.
> Does anyone else experience the same problem or have any ideas how to
> solve it? I'm no USB guru an every other USB device I have seems to
> work properly and at full speed. dmesg shows no messages (on PC) and
> it is running USB 2.0 etc.
> So far my only workaround is to copy/sync/copy/sync/copy/sync but
> that's annoying. However, the difference of taking 1 minute to write
> 1gb versus taking 20 minutes to write 1gb is also annoying.
> Thanks :)
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