[PD] GEM performance problem on ubuntu 64 bit and/or mac hardware?

[Mathieu Bouchard]

On Sun, 3 Oct 2010, Matteo Sisti Sette wrote:

> She has tried a patch which plays 4 videos at the same time and she 
> experience much worse performance than I do with the same patch and same 
> videos on my intel core duo 2.1 GHz pc. I'm not sure if the macbook may 
> have a slower hard disk or a less powerful gpu, but the difference in 
> performance is about a factor 2, it's huge.....

Try it with four videos short enough so that the hard disk is not getting 
accessed after they have looped. Then measure performance while the hard 
disk is not being accessed. This will give you figures independent of 
hard-disk speed.

It's not just the speed of the hard-disk and GPU, it's also the speed of 
the connector between the CPU and the GPU, and the connector between the 
CPU and the hard disk.

Also the speed of the hard disk differs depending on whether your data is 
fragmented. If you have four "defragmented" files you are trying to read 
continuously little bit by little bit, you're actually doing a very 
fragmented reading. What happens if you glue together the four videos as 
one big video ? does the hard disk work less ?

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| Mathieu Bouchard ------------------------------ Villeray, Montréal, QC