On Wednesday 02 February 2005 21:44, Timothy Miller wrote:
> I am aware of one architecture which can periodically write the "read
> pointer" to a location in host memory, so that the host doesn't incur
> any bus overhead to computer free ring buffer space.

Yes, I was playing around with some advisory strategy like that, but 
then I thought, under load it's hopefully going to interrupt only about 
200 Hz, so reading the register is a tiny overhead.

The behavior of the simple strategy under heavy load is looking quite 
decent.  The next thing to think about is the behavior when traffic is 
relatively light and consisting of lots of sparsely spaced bits and 
pieces, so that the queue is constantly draining.  It would be nice if 
the ring buffer could do the entire job, so externally visible drawing 
registers aren't needed as well.

I think somebody mentioned the idea of a programmable delay between the 
queue emptying and triggering the queue empty interrupt.  This might be 
just the thing.

Regards,

Daniel
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