Re: [Libusb-devel] Bulk transfers and packet size

[Jef D. <jef...@ho...>]

On 25/01/11 22:07, Till Harbaum / Lists wrote:
> Am Dienstag 25 Januar 2011 schrieb Jef Driesen:
>> When I said "a large number of bytes", I didn't really mean very large (as in
>> many megabytes), but large compared to the usb packet size. The total amount of
>> data for my application is in the order of KB (I don't have the exact specs
>> yet). I suppose that could make a difference.
>
> Sending a few kilobytes should only take a very small time. What's the point of showing a progress bar then? And yes, this will have an impact as drawing the progress bar likely consumes more cpu power and takes more time than just sending a few kilobytes over usb.

Well I'm used to work with serial I/O and, depending on the protocol used (some 
are not very efficient), sending a couple of KB can take several minutes and you 
really want that progress bar. But regardless of the transfer speed, I provide 
an uniform api which includes support for progress events.

Anyway, if it turns out the data is received so fast that a progress bar is 
useless, then it's fine to update the progress only after the entire transfer. 
It's just that I don't have a good idea about these things because usb is 
completely new to me.