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#440
blu
Participant

Just an update on branch-prediction PMU counters in kernel 4.4.52-armada-17.06.2-gcaa3a4f + U-Boot 2017.03-armada-17.06.3-ga33ecb8:

$ perf stat -e task-clock,cycles,instructions,branch-misses,armv8_cortex_a72/inst_retired/,armv8_cortex_a72/br_pred/,armv8_cortex_a72/br_mis_pred/ -- ./a.out 

 Performance counter stats for './a.out':

       4500.194400      task-clock (msec)         #    1.000 CPUs utilized          
     5,850,215,516      cycles                    #    1.300 GHz                    
     3,205,528,984      instructions              #    0.55  insns per cycle        
       200,035,171      branch-misses             #   44.450 M/sec                  
     3,205,528,984      armv8_cortex_a72/inst_retired/ #  712.309 M/sec                  
     1,001,588,793      armv8_cortex_a72/br_pred/ #  222.566 M/sec                  
       200,035,171      armv8_cortex_a72/br_mis_pred/ #   44.450 M/sec                  

       4.501076183 seconds time elapsed

So by the earlier formula:

armv8_cortex_a72/br_pred/armv8_cortex_a72/br_mis_pred/ = 800M

armv8_cortex_a72/br_mis_pred/ / (armv8_cortex_a72/br_pred/armv8_cortex_a72/br_mis_pred/) = 200M / 800M = 0.25

Which is the expected result. I’m happy : )

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