I am very pleased that we are pursuing these optimizations :) I'll get some real numbers later tonight (about 8-10 hours from now).
----- Original Message ----- From: "Robert Osfield" <[EMAIL PROTECTED]> To: "OpenSceneGraph Submissions" <[email protected]> Sent: Wednesday, September 17, 2008 10:52 AM Subject: Re: [osg-submissions] Platform independent matrixmultiplicationoptimization Hi James, Now the Mathias changes are checked in could you do some testing at your end to see how they affect performance, and whether they do make the need for SSE optimizations redundant. Once we get a feel for this then we can come back to discussing SEE optimizations. Robert. On Wed, Sep 3, 2008 at 2:01 PM, James Killian <[EMAIL PROTECTED]> wrote: > I sure hope Robert will "make" time to merge this. I was about to ping > again on this subject... I'll glv (get latest version) or merge these > locally and profile to see if matrix mult is heavily used in our game. It > is not a question of if the SSE optimization would improve upon the changes > already made here, it is more of a question of if the gain is still > significant enough to be worth the effort. With the code you previously > sent me the answer is yes it was for our game. > > Thanks for this submission! > > James Killian > ----- Original Message ----- From: "Mathias Fröhlich" > <[EMAIL PROTECTED]> > To: <[email protected]> > Sent: Wednesday, September 03, 2008 6:51 AM > Subject: [osg-submissions] Platform independent matrix > multiplicationoptimization > > > > Hi Robert, > > I have attached a change to the matrix multiply stuff. > This is a generic optimization that does not depend on any cpu or > instruction > set. > > The optimization is based on the observation that matrix matrix > multiplication > with a dense matrix 4x4 is 4^3 Operations whereas multiplication with a > transform, or scale matrix is only 4^2 operations. Which is a gain of a > *FACTOR*4* for these special cases. > The change implements these special cases, provides a unit test for these > implementation and converts uses of the expensiver dense matrix matrix > routine with the specialized versions. > > Depending on the transform nodes in the scenegraph this change gives a > noticable improovement. > For example the osgforest code using the MatrixTransform is about 20% slower > than the same codepath using the PositionAttitudeTransform instead of the > MatrixTransform with this patch applied. > > If I remember right, the sse type optimizations did *not* provide a factor 4 > improovement. Also these changes are totally independent of any cpu or > instruction set architecture. So I would prefer to have this current kind of > change instead of some hand coded and cpu dependent assembly stuff. If we > need that hand tuned stuff, these can go on top of this changes which must > provide than hand optimized additional variants for the specialized versions > to give a even better result in the end. > > An other change included here is a change to rotation matrix from quaterion > code. There is a sqrt call which couold be optimized away. Since we divide > in > effect by sqrt(length)*sqrt(length) which is just length ... > > The change is based on rev 8828. > > Greetings > > Mathias > > -- > Dr. Mathias Fröhlich, science + computing ag, Software Solutions > Hagellocher Weg 71-75, D-72070 Tuebingen, Germany > Phone: +49 7071 9457-268, Fax: +49 7071 9457-511 > -- > Vorstand/Board of Management: > Dr. Bernd Finkbeiner, Dr. Florian Geyer, > Dr. Roland Niemeier, Dr. Arno Steitz, Dr. Ingrid Zech > Vorsitzender des Aufsichtsrats/ > Chairman of the Supervisory Board: > Prof. Dr. Hanns Ruder > Sitz/Registered Office: Tuebingen > Registergericht/Registration Court: Stuttgart > Registernummer/Commercial Register No.: HRB 382196 > > > > > -------------------------------------------------------------------------- ------ > > >> _______________________________________________ >> osg-submissions mailing list >> [email protected] >> >> http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org >> > > _______________________________________________ > osg-submissions mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org > _______________________________________________ osg-submissions mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org _______________________________________________ osg-submissions mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org
