Re: Hitting 60 Hz in Unreal Engine 3 (was:botheringwith C# for 3D)

It's been a while, but I believe the nature of how things work causes
particularly bad performance with lots of L2 misses.  We particularly miss
attempting to figure out where to go next due to all the VFs and the
compiler not having a clue what to do with the code all scattered to the
winds.

As well, since Profile Guided optimization wasn't really a practical option
on PS3 we didn't bother turning it on for 360.  System specific
optimizations with no practical path on the other platform are generally a
no-no for us (unless that platform is already behind and this just catches
it up).

So, sort of a perfect storm.  And yeah, nothing to say to really contradict
anything that was already said :)

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Richard
Sent: Sunday, February 14, 2010 12:27 PM
To: [email protected]
Subject: Re: [Sweng-Gamedev] Hitting 60 Hz in Unreal Engine 3
(was:botheringwith C# for 3D)


In article <1AF87C46295E4A8DBD2E8E79E389DBBD@BigBoy>,
    "Jon Greenberg" <[email protected]>  writes:

> FYI I'm the one who gave the GDC talk on UE3 at 60Hz.  Wasn't aware you
guys
> were discussing the presentation on sweng-gamedev.  I'd be happy to answer
> any questions anyone has about the talk (as much as I'm allowed to
anyway).

I think all my questions were answered in the discussion we had;
unless you think the discussion was off the mark.

> The specific reference to virtual functions - which isn't obvious from the
> slides themselves - is to pixel/vertex shader setup found in UE3's render
> thread.  A lot of the behaviour involved the invocation of VF's, at the
time
> often for lazy retrieval of values where even straightforward local
caching
> of values would help.  Since most of the render thread time was spent
> executing the shader setup stuff, reducing VF calls had a sadly dramatic
> impact on performance.

Interesting.  Would you agree that it was the deleterious effect on
the data cache that was the root cause of the slowness of using VF's
here?
-- 
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
 <http://legalizeadulthood.wordpress.com/the-direct3d-graphics-pipeline/>

      Legalize Adulthood! <http://legalizeadulthood.wordpress.com>
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