Re: Source for Cr overhead

Niraj Tolia wrote:
> Hi Brian,
> 
> We are using fairly recent Cr CVS code for QuakeViz (an earthquake 
> modeling app from http://www.cs.cmu.edu/~quake/>. Our testing right 
> should not be stressing a system as we rotate an small model in a 
> 640x480 window. However, we see a very significant difference in the 
> nubmer of frames/sec.
> 
> Attached is a graph of a particular interactive benchmark.

I don't see an attachment.


> Thick is 
> simply running the model on NativeGL (Linux) and measuring the number of 
> glxSwapBuffer() calls. Chromium loopback is using the Cr renderer on the 
> same machine as the application. Do you know why there is suck a stark 
> difference in performance? The overhead of using TCP + GL 
> Marshalling/Unmarshalling? Any thoughts would be helpful.

Going over the network is always a lot slower than the local graphics 
card.  How much slower depends on various factors like the network 
speed itself (no surprise there).

Using display lists is one potential way to increase performance since 
you can draw quite a bit with a few, small glCallList commands.

Another simple thing you can do is run 'top' on the hosts to see if 
any of them are CPU limited.


> PS I kept this email off list for now. However, if you feel it would be 
> helpful to others, feel free to cc the list on the reply.

I'm cc'ing the Chromium dev list in case anyone else has anything to add.

-Brian


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