[petsc-users] Parallelization efficiency diagnose

[Jed Brown]

"Sun, Hui" <hus003 at ucsd.edu> writes:

> Estimation of possible speedup of MPI programs based on Streams benchmark.
>
> It appears you have 1 node(s)
>
>
> Does this result basically says that my MacBook only have one node?
> However, I know my computer has 4 cores, as I type sysctl -n hw.ncpu
> in bash, it gives me 4. What does it really mean? By the way, here is
> my configuration for this installation:

Use "lstopo" from the hwloc package to see how your cores are laid out.
You probably have two physical cores, each with hypethreading (4 logical
cores), sharing the same memory bus.  One thread saturates the memory
bus, so you get no speedup by using more cores.

http://www.mcs.anl.gov/petsc/documentation/faq.html#computers
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