Re: Texture Paging

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'Bwana' Bob Buckley (BBuckley++at++jntf.osd.mil)
Thu, 04 Nov 1999 14:38:45 -0700

Success! I am trying to render to 2 separate pfPipeWindows and in not
setting them up to share resources I was getting a context switch of
some sort and each pwin caused a texture page of the same texture. It
was like it split up texture memory between the 2 pwins and if either of
them went over their limit then paging was invoked. So, I caused each
subsequent pwin to attach to the first and set their share masks to
share darn near everthing, especially the display lists and textures
(GL_OBJS).

The info on the Octanes scares me. Yech!

Angus Dorbie wrote:
>
> oops, forgot to cc everyone.
>
> Basically the IMPACT GFX system has some page structure to TRAM which
> the texture memory manager can't make 100% efficient use of under some
> circumstances.
>
> To get best memory use the pfu's to build the texture list before
> download. They perform some component sorting for memory useage
> efficiency on IMPACT.
>
> Cheers,ANgus.
>
> 'Bwana' Bob Buckley wrote:
> >
> > Angus, hopefully, you can tell me why I'm paging textures. I'm running
> > on a Octane with 4Mb of texture memory and Performer V2.2.6
> >
> > The database I have include two distinct pfTextures:
> >
> > Texture #1
> > 256 X 256 X 2 = 131072 bytes
> > loaded as default (2 bytes per texels)
> >
> > Texture #2
> > 1024 X 512 X 4 = 2097152 bytes
> > loaded as RGBA_8 (4 bytes per texel)
> > bilinear min filter
> > trilinear mip map mag filter.
> > Hence, 4/3 * 2097152 = 2796203 bytes
> >
> > I'm running pfuDownloadTexList which confirms all but the additional
> > memory required for the mip mapping.
> >
> > In channel #1 I load
> >
> > Texture #1
> > Geostate #1
> > texture enabled
> > transparency enabled
> > lighting disabled
> > default texenv
> >
> > Texture #2
> > Geostate #2
> > texture enabled
> > default texenv
> >
> > And in channel #2 I again load texture #2 but attached to a different
> > geostate:
> >
> > Texture #2
> > Geostate #3
> > texture enabled
> > lighting disabled
> > default texenv
> >
> > I'm getting texture paging with avg loads equal to 1.0 and kbytes of
> > 2097.152
> > I watch the number of loads go from 0 to 24 then it repeats itself
> > (i.e., after it loads 24 straight times it doesn't load for a single
> > frame, then starts loading again).
> > This repeating behavior changes when I run with breaks in cvd.
> >
> > Are there any blatant errors I'm making in the way in which this machine
> > (or other Iris') can handle this situation? I am aware of some of the
> > banking restrictions of the iRs but know little of the Octanes.
> >
> > If nothing is real obvious I can probably put it into a test case and
> > work from there.
> >
> > Help!
> > Thanks!
>
> --
> "Success is the ability to go from one failure to another with
> no loss of enthusiasm." - Winston Churchill.
>
> Performer + OpenGL examples and tutors: http://www.dorbie.com/
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> List Archives, FAQ, FTP: http://www.sgi.com/software/performer/
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