[Libdlo] [PATCH] udlfb: high-throughput urb pool

[Bernie Thompson]

One more thing..

On Saturday, December 18, 2010, Bernie Thompson
<bernie.thompson at gmail.com> wrote:
> Also, if we're not filling the 64K buffers (if defio is sending us
> just a few pages at a time), then also try reducing the 64K buffer
> size, and increasing the number of buffers accordingly.

Another parameter to adjust is the defio delay (defined in udlfb.h). I
think it's currently set to 5 (nearly immediate scheduling) because I
subjectively felt mouse lag at higher values.  But that means we're
probably getting notification of only a few dirty pages at a time. And
for the video playback scenario, almost certainly a longer
accumulation of dirty pages would be more favorable.

If you find a better value for that parameter (accounting for what's
basically the opposite ends of the spectrum - mouse movement vs. full
screen video playback), we can definitely update.

If anyone can come up with a strategy for dynamically adjusting the
value (e.g. triggered by thresholds on how many buffers are unconsumed
out of our pool), that's definitely worth considering too.

Best wishes,
Bernie