Sun sparc vii m9000

Question

I wanted to understand the CPU architecture of SUN SPARC VII M9000 series servers. prtdiag command shows that it has 8 core attached to a physical CPU. Are these physical cores ? What is L1, L2 and L3 caches architecture for this ?

What is the maximum number of threads I can run if the available number of CPUs are 8. ie. 64 cores.

Are these cores a type of hardware threads?

Thanks for the answer.

Since it is SMT, can it scale upto 64 threads. I have some observations: till 32 threads running parallely takes 8 to 9 secs for each thread to complete. Trying beyond 32 threads time taken to complete grows non linearly and reaches 14 sec for 64 threads.

But if we have dedicated cores the same program on other machines shows the same time taken for the maximum number of threads.

Instruction are being fetched for two threads in this architecture, and then pipelined to provide the execution cycle during memory access. (If my understanding is correct). Question: 1. Is it correct to take this architecture not suitable for cpu intensive multi threaded programs. 2. Application should have a mixture of I/O and CPU jobs to utilize it correctly.

Answer 1

SPARC VII processors have 4 cores and Simultaneous MultiThreading (SMT) which allows them to run 8 threads simultaneously.

L1 cache is 128Kb per core and L2 cache is 6Mb per CPU chip there is no L3 cache.

8 CPUs will allow for simultaneous execution of 64 threads.

You appear to be getting threads and cores confused. Each CPU contains 4 cores. Each core can execute 2 threads simultaneously.