capslock118
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does the 512 model increase the GPU performance?

Fri Nov 16, 2012 1:27 am

i haven't read this explicitly.

On the one hand I assume no, however given that there are various start.elf files you can choose from, I assume that maybe that means there is an increase in video performance?

I'd to upgrade my pi server to a 512 model and donate the other, but now I am wondering if maybe I should do the same for my media center pi; however I'm not sure if that is really worth it given my current 256 model handles being a media server just fine for the most part.

dknute
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Joined: Thu Nov 08, 2012 9:05 pm

Re: does the 512 model increase the GPU performance?

Fri Nov 16, 2012 10:03 am

Define "performance".

In order to answer your question you must first identify the limiting factors in your current design. So, for example, if you need a lot of GPU memory and are running 128/128 split and with that the amout of system memory is simply not enough for all the applications then you'll get a lot of swapping. Virtual memory is much slower than real one and even more so on RPi where the SD access is not exactly lightning fast. In this case you would benefit from having 512MB model. But this is a very specific scenario.

Neither CPU nor GPU in RPi will became any faster just by having more RAM attached. There would be some difference if the RAM was not just bigger but also faster (lower latency for example). Not the case here as I understand it. In the end the important thing is how you use the hardware.

As a side note, in current firmware there's just one start file and the memory split is defined by an option in config.txt. Well, two start files, one is needed for extreme case with GPU having only 16MB assigned, but it will be selected automatically for you, no need to touch anything but the config file.

james968
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Joined: Tue Jul 17, 2012 8:52 am

Re: does the 512 model increase the GPU performance?

Fri Nov 16, 2012 10:11 am

I usually see a fair amount of swap space used. Though it doesn't seem to be hitting it too much.

If you are in a situation where the system is using Swap (usually on a slow SD card) vs you have more memory and it uses RAM. RAM will show better performance.

James

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Burngate
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Re: does the 512 model increase the GPU performance?

Fri Nov 16, 2012 10:40 am

As said above, extra memory will reduce the need for swap - but that is the Linux, Arm side. The GPU doesn't swap.

Having extra memory allows you to give the GPU more, while keeping enough for the ARM to do what you want in.
However, if 128M allows the GPU to do what you need it to do, then giving it more won't help.

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