Comment 153 for bug 500069

Experienced similar issue as comment #12. However I witnessed the following:
1. a normal copy by nautilus was going. The speed was around 2.9M/s and in iotop I saw this: in one update, a write operation around 3M/s happened, in the next 2 updates no read/write operation happened. This pattern was repeatedly happen in iotop.

2. I did the trick I mentioned above to force Linux to flush its caches. I saw a constant write operation in iotop from 3 to 6 M/s. nautilus stalled for a while until buffers were flushing. Unfortunately, I didn't see the final speed shown by nautilus. But considering iotop results, the speed should be better than normal case (2.9M/s)

3. I did another copy of another directory, but it was even slower than 2.9M/s. I undone my changes to kernel parameters and nautilus suddenly finished the copying (which actually copied into memory). I don't know if the actual write was faster or slower.

Unfortunately, I forgot to test with one big file rather than a number of small files. But considering what happened in number 2 above, I'd assume that Linux still needs to better manage its in-RAM buffer for slow USB devices.