Am Dienstag, 29. Oktober 2002 15:09 schrieb Keith Whitwell:
> Felix Kühling wrote:
> > On Tue, 29 Oct 2002 13:23:22 +0000
> >
> > Keith Whitwell <[EMAIL PROTECTED]> wrote:
> >>Felix,
> >>
> >>I've cleaned up the WaitForFrameCompletion function a bit & committed.
> >> The logic is slightly different, but a lot easier to read/understand, I
> >> think.
> >
> > Ok, I just think that the name rmesa->irqsEmitted is now a bit
> > misleading (can't think of a better one, though).
>
> Agreed, I can't either.
>
> > And you removed the
> >
> > delay loop. I remember reading a comment like "don't hammer the bus" in
> > the old code. And by removing the delay loop you also eliminated the
> > cause for the IRQ/busy ping ponging. So the irqsEmitted magic should be
> > no longer necessary.
>
> The delay loop is eliminated by modern versions of gcc anyway. The
> irqsEmitted magic is still necessary to avoid the (first) busywait, which
> I'd like to do. It basically says: "If I have to emit an irq for this
> frame, then don't try to do without them for at least 9 more frames". This
> should stop the pingponging in all but very marginal situations, and then
> it won't be more than 1 pingpong per 10 frames.
>
> > Finally, if do_irqs is disabled you alsways use usleeps. But I assume
> > it's your intention to never do real busy waiting.
>
> No - there's an 'if (rmesa->do_usleeps)' protecting all relevent uses of
> usleep, I think.
Have you great two guys latency (kernel preemption) in your mind, too?
Latest test I did with 2.5.44+ (preemption enabled as always ;-) showed really
"bad" latency (~15 ms and more vs ~2ms with 2.4.17-aaX-2.4.19-preX-aaX) for
the gfk subtest of latencytest0.42-pn.
Regards,
Dieter
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