On Sun, Sep 29, 2013 at 7:51 PM, Markus Rechberger
<mrechber...@gmail.com> wrote:

>
> I agree, but here not only small buffers are the problem, also latency.
>
> I will send another patch version which overrides the SG transfer once
> a preallocated buffer is submitted. The current patch will only use
> the pre-allocated buffers if the buffer size is smaller than 15-16k.

If you put much attention to performance & latency, I am wondering why
you don't write a kernel mode usb driver to fix your problem?  With usbfs
and user mode driver, both performance and latency won't be very good:

- URB can only be submitted in process context with context switch cost
- URB complete is notified by signal, which might introduce much latency

With one kernel mode driver, you can get better performance/latency much
easily.


Thanks,
-- 
Ming Lei
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