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I have collected data of Number of L2 cache misses using PAPI. I had run an MPI application with 4 threads (mpirun -np 4) and each thread reads the cache misses in L2. Each thread outputs data for every timestamp. eg:

Timestamp              data
xxx530     thread# 0   2136
xxx531     thread# 0   3217
..           .          .
.            .          . 
.            .          .
.            .          .
xxx550      thread# 0   412334255

xxx530      thread #1    2456
xxx531      thread#1     4243
xxx532      thread #1    4567 
and so on

Now my qstn , is whether i shud add all the cache miss values at time stamp xxx530 for thread 0,1, 2 and 3 OR shud i take the max-value for thrreda0,1,2,3 for timestamp xxx530 ?

Sharat Chandra
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  • can you modify your programm and dont' do a work with memory in some thread. Then you will get the counter from this thread and choose the variant ("Sum" or "Max" -- in other words - Per-Thread counter or System/CPU-wide counter) – osgx Nov 10 '10 at 04:39

1 Answers1

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The bare L2 cache miss count is no use.

You should also count cache hits/ or memory access count to get some useful info.

osgx
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