RE: [Xen-devel] theoretical network rx performance of Windows with PVdrivers

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> >
> > I don't think evtchn->IRQ latency is particularly large. But also I
> > don't know what else might be causing your erratic behaviour.
> >
> 
> That's probably all I needed to know for now. I think it might
actually
> be Windows that's the problem...
> 

*sigh*

I was queuing the next dpc (under windows, the dpc is the bit that get
scheduled by the isr and runs at a lower priority than the isr but
higher than normal user code) and then measuring the time until the next
dpc occurred. I also re-queue another dpc when too much work has been
done by the current instance to try and even out the load a bit - dpcs
are supposed to complete in microseconds. When there was a large delay
between the queuing and the executing of the dpc I assumed it was
windows delaying it for some reason, but it's my code after the
re-queuing and the end of the dpc that is delaying things. There is
still a problem with Windows taking too long to do things, but it's not
where I thought it was.

I guess I'm just too used to everything being Windows's fault :)

Thanks

James

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