On Thu, 10 Dec 2009, Hadmut Danisch wrote: > I just produced the usbmon trace, (250k compressed) and put it to > > http://www.danisch.de/tmp/mon_0u_out.bz2 The advantage of attaching the trace to the bug report is that it will still be available for people to look at long after you have removed it from your server. > (no other usb device had been in use while doing the test) That's not correct. The trace shows that a device attached to port 2 (the card reader was on port 3) was quite active while your test was running. > I tried to copy a 623 MByte file onto a 2GB SD flash card with a dos > file system. > > As always, the first 130 MByte were copied extremely fast (maybe that > went just into the fs/block cache and had not yet been written > to the device. Then the du or ls-lF show the file staying at 130 mb for > a while, then it very slowly reaches 137 and 141, and then it is as good > as frozen. The trace shows two things. First, some program is probing your flash card much more frequently than it should, about once every 30 ms. Normally hal probes once every 2 seconds, so I don't know what's causing all these extra probes. But luckily they don't interfere with the data transfer very much. The real problem appears to be a bug in your hardware. Every five seconds or so the reader appears to crash and has to be reset. This takes around three seconds, during which time no data can be transferred. During the periods when it was working, I estimate the reader was handling about 3.5 MB/s. The trace does not show the transfer stopping completely. It was still going strong at the end of the trace. Maybe the bug is in the USB hardware on your computer instead of the card reader. I can't tell which. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
