From: Tom Flynn (flynnt++at++engr.sgi.com)
Date: 04/09/2003 13:51:46
On Tue, 1 Apr 2003, Dorosky, Christopher G wrote:
> Try loading esprit.flt three times in perfly.
> perfly esprit.flt esprit.flt esprit.flt
> I get this, with pipe stats.
> Immediate 1.8, display lists 2.2
On a GeForce3 (My GeForce4 is in someone else's machine at the moment), I
get Immediate 6.9, display lists 6.7. there is a temporary increase in
draw time 7.1/7.2ms while building the display lists, but afterwards the
draw time drops to 6.6/6.7ms.
> With my complex models, this is what I get as well, but worse.
> The cow did get faster though.
>
> So what's up with that? Are display lists inefficient on certain models?
it would depend on the hardware and the data and maybe the driver.
generally display lists are faster because their data can be stored in
memory on the gfx hw. it's faster for the gfx hw to access and also
saves bandwidth in the pipeline because the data is not sent
down every frame. you also save OpenGL call dispatch times when using
display lists since issuing display lists is generally just glCallList()
as opposed to calling glBegin(), glColor3f(), glVertex3f(), ..., glEnd().
i, personally, haven't seen display lists be slower than immediate mode.
i would have to speculate as to how that could occur.
one speculation is perhaps the display list was stored in host memory
rather than gfx memory and is being dma'd separately. maybe this is
happening because the gfx card has run low on memory or the memory is too
fragmented to have room for the display list.
for the moment, i'm at a loss for what else could make display lists
slower than immediate mode.
-tom
>
>
> -----Original Message-----
> From: Tom Flynn [mailto:flynnt++at++cthulhu.engr.sgi.com]
> Sent: Thursday, March 27, 2003 4:05 PM
> To: Dorosky, Christopher G
> Cc: 'info-performer++at++sgi.com'
> Subject: Re: [info-performer] Performer and display lists
>
>
>
> well, on my linux box with geforce4, i can bring up perfly cow.obj
> bring up pipe stats (the default stats use stippled lines, which are
> slow), hit 'd', and watch the draw time drop from 2.0ms to 1.6ms.
> on a higher polygon model i've got, it went from 109.8ms to 62.2ms.
> looks faster to me.
> -tom
>
> On Thu, 27 Mar 2003, Dorosky, Christopher G wrote:
>
> >
> > In GL, display lists are supposed to be faster (for static stuff).
> > So how come, if I load a model in perfly, and hit "d" (makes it compile
> and
> > use a display list) that I get worse timings than
> > using the default "i" immediate mode?
> >
> > This is under Linux, with a GeForce4.
> >
> > Chris
> >
> > Christopher Dorosky
> > Lead Electronic Systems Engineer - Real Time Simulation, TOPSCENE
> > Lockheed Martin Missiles and Fire Control - Dallas
> > christopher.g.dorosky++at++lmco.com
> > 972-603-2349
> >
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>
> --
> "Mongooses are famous for their snake-fighting ability, and are
> almost always victorious because of their speed, agility, and timing
> and also because of their thick coat."
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-- "Mongooses are famous for their snake-fighting ability, and are almost always victorious because of their speed, agility, and timing and also because of their thick coat."
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