Re: XF4 on Mach64 and 2.2 kernel?
Sven LUTHER wrote:
>
> On Mon, Dec 04, 2000 at 04:29:24PM +0100, Michel Dänzer wrote:
> > Sven LUTHER wrote:
> >
> > > > > Adam C Powell IV wrote:
> > > >
> > > > Hmm, given your warning, maybe I'll stick to fbdev for now. It's fast
> > > > enough for everything- except hashing the screen during a GNOME
> > > > logout, but I don't do that too often. :-)
> > >
> > > Not sure if here is the right place for this, but i noticed that
> > > supplying the clipping pseudo accel will improve this a lot. Is there
> > > any chance that this accel could be supported by the fbdev driver ?
> > > It would need support from the fbdev, isn't it ?
> >
> > I'm not convinced at all. For now, fbdev doesn't use XAA at all, so I
> > can't imagine how just enabling it for nothing (?) could help any.
> > However, this is one of the rare cases where I'd really like you to go
> > ahead and prove me wrong. :)
>
> Did you see the other mail talking about the gnome logout being slow when
> shadowfb was activated, are you able to confirm this ? if yes, then it is a
> problem with shadowfb. Now i remember that when i tried the just clipping
> accel driver, i had to use accel, which disables shadowfb. Maybe this was
> the source of the problem.
Sounds very plausible to me.
> I don't know shadowfb enough to know how it works, but i guess you write to
> the shadowfb, which in turn get copied to the true screen every now and
> then.
Yes. The ShadowFB we are talking about does the copy after each operation.
Keith Packard wrote another shadow framebuffer implementation for Tiny X which
only does it in regular intervals which should further improve performance at
the cost of latency, don't know if it will (or even can) be integrated into
the 'normal' XFree86 server.
> I guess what happens is that the gnome logout screen does some very small
> writing to the shadowfb, and it has to be copied (all of the shadow buffer
> ?) to the screen after each line draw or so.
>
> Am i wrong in this ?
Yes and no. :)
GNOME draws stippled rectangles, which leads to the whole area of the
rectangles being copied from the shadow framebuffer to the real one. If it
drew the rectangles using four lines instead, it should be much faster.
Michel
--
Earthling Michel Dänzer (MrCooper) \ CS student and free software enthusiast
Debian GNU/Linux (powerpc,i386) user \ member of XFree86 and The DRI Project
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