When is a program limited by the memory bandwidth?

Posted by hanno on Stack Overflow See other posts from Stack Overflow or by hanno
Published on 2010-06-01T18:30:14Z Indexed on 2010/06/01 18:33 UTC
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c

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linux

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memory-management

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hpc

I want to know if a program that I am using and which requires a lot of memory is limited by the memory bandwidth.

When do you expect this to happen? Did it ever happen to you in a real life scenario?

I found several articles discussing this issue, including http://www.cs.virginia.edu/~mccalpin/papers/bandwidth/node12.html http://www.cs.virginia.edu/~mccalpin/papers/bandwidth/node13.html http://ispass.org/ucas5/session2_3_ibm.pdf

The first link is a bit old, but suggests that you need to perform less than about 1-40 floating point operations per floating point variable in order to see this effect (correct me if I'm wrong).

How can I measure the memory bandwidth that a given program is using and how do I measure the (peak) bandwidth that my system can offer?

I don't want to discuss any complicated cache issues here. I'm only interested in the communication between the CPU and the memory.

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