Re: [Xen-devel][PATCH][RFC] Using data polling mechanism in netfront toreplace event notification between netback and netfront

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 10/09/2009 09:03, "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote:

> I experimented with this in Windows too, but the timer resolution is too
> poor. I think you should also look at setting the 'event' parameter too.
> The current driver tells the backend to tell it as soon as there is a
> single packet ready to be notified (np->rx.sring->rsp_event =
> np->rx.rsp_cons + 1), but you could set it to a higher number and also
> use the timer, eg "tell me when there are 32 ring slots filled, or when
> the timer elapses". That way you should have less problems with
> overflows.
> 
> Also, I don't think you need to tell the backend to stop notifying you,
> just don't set the 'event' field in the frontend and then
> RING_PUSH_RESPONSES_AND_CHECK_NOTIFY in the backend will not return that
> a notification is required.

Yes, the ring event mechanism is already set up for supporting event
holdoff/mitigation. It's just not used smartly by netfront right now.

 -- Keir



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