Re: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6

Alan Stern
2019-08-20T17:13:33Z

On Mon, 19 Aug 2019, Andrea Vai wrote:

> Hi Alan,
> I attach the two traces, collected as follows:
>
> - start the trace;
> - wait 10 seconds;
> - plug the drive;
> - wait 5 seconds;
> - mount the drive;
> - wait 5 seconds;
> - copy a 500 byte file;
> - wait 5 seconds;
> - unmount the drive;
> - wait 5 seconds;
> - stop the trace.

Still no noticeable differences between the two traces. They both
include a 1.2 second delay shortly after the writing starts, and the
initialization sequences are the same.

I really don't know where to look for this. The only thing I can think
of at this point is to repeat this test, but using a file large enough
for the difference in writing speed to show up plainly.

By the way, it would be best to run the tests with the smallest
possible number of other USB devices plugged in. None at all, if you
can arrange it.

Alan Stern