libusb performance on 8.1

Daniel O'Connor doconnor at
Fri Jan 28 08:43:08 UTC 2011

On 28/01/2011, at 18:28, Hans Petter Selasky wrote:
> For this kind of applications ISOCHRONOUS transfers should be used. Then you 
> can have a double buffer guard in the range 1-56ms, regardless of the buffer 
> size the hardware uses.

Hmm, OK, I will have a look at changing it, although it is a bit of a pain because you can't stall an ISO EP and I'm using stall to indicate an error.

Is it possible to change the amount that is buffered? This is a specialised application so a custom kernel is no problem. Even a hint in the right direction would be greatly appreciated :)

> You could also try an XHCI controller, because the BULK buffering is done 
> differently there.

OK thanks, I'll try that too.

>> I obviously don't need any more
>> throughput, however my application is very sensitive to latency, as I am
>> reading out of a fairly small FIFO and if it fills up my entire run has to
>> be aborted.
> --HPS

Daniel O'Connor software and network engineer
for Genesis Software -
"The nice thing about standards is that there
are so many of them to choose from."
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