[petsc-users] CPU speed or DRAM speed bottlenecks ?

[C B]

Resorting to your expertise in software performance:

Subject: Looking for a crude assessment of CPU speed or DRAM speed
bottlenecks in shared memory multi-core PCs

On a typical PC with one Xeon CPU (8 cores),  a serial code runs a case in
say 10 hours of Wall time, and on the same computer 4 instances of the same
code running simultaneously (the same case) take essentially the same Wall
time, 10 hrs or a marginal increase such as 10hrs 30 mins.   There is no
I/O, lots of free physical RAM, each core running an instance shows ~ 100%
utilization.

Q1: What could we conclude about this hardware-software-case combination in
terms of being CPU bound, memory bandwidth bound, etc ?

Q2: Can we say that this hardware-software-case combination is not DRAM
bound, and that it “may be amenable” to a good speedup running multiple
threads in the same shared memory environment ?

I did look into the shared memory benchmark
http://www.cs.virginia.edu/stream  but I could not draw any conclusions.

If this is a trivial question, please point me to a good resource to learn.

Thanks!
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