perf profiling in Linux

2
votes

If I ask perf list to tell me what I can do, it says

  LLC-loads                                          [Hardware cache event]
  LLC-load-misses                                    [Hardware cache event]
  LLC-stores                                         [Hardware cache event]
  LLC-store-misses                                   [Hardware cache event]
  LLC-prefetches                                     [Hardware cache event]
  LLC-prefetch-misses                                [Hardware cache event]

However, if I ask perf stat -eLLC-load-misses ls, it tells me

   <not supported> LLC-load-misses         

       0,001647655 seconds time elapsed

Is it supported or not? What am I doing wrong?

1
linuxprofilingperf
What architecture you are running this on? - Milind Dumbare
I guess perf list gives you what the software perf can do with proper support from the hardware; with the second one you get what is actually supported on your machine. So, I think you don't do anything wrong. - Ali

1 Answers

1
votes

There could be various reasons why the counter is shows as "not supported"

Following are few of them

  • You are running the perf on some Virtual hardware inside Virtual machine

  • The architecture itself does not have such counter. You have to check the Architecture specs to find out if the counter is supported

P.S. if you see "not counted" it means you need to enable the kernel support for the counters. Which is not in your case.