On Mon, Jun 10, 2013 at 4:43 PM, Oliver Neukum <oliver@xxxxxxxxxx> wrote: > On Sunday 09 June 2013 23:18:28 Ming Lei wrote: >> 2), the biggest change is the situation in which usb_submit_urb() is called >> in complete() callback, so the introduced tasklet schedule delay might be a >> con, but it shouldn't be a big deal: >> >> - control/bulk asynchronous transfer isn't sensitive to schedule >> delay > > That is debatable.Missing a frame boundary is expensive because the increased > latency then translates into lower throughput. Suppose so, considered that bulk transfer will do large data block transfer, and the extra frame or uFrame doesn't matter over the whole transfer time. Also the tasklet function will be scheduled once the hard interrupt handler completes, and the delay is often several microseconds or smaller, which has a very low probability to miss frame/uframe boundary. Even with submitting URBs in hardware interrupt handler, there is still the interrupt handling delay, isn't there? (So disabling interrupt too long is really very bad, :-)) Thanks, -- Ming Lei -- 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
