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> I did not manage to find any good tutorial on debugging cache misses in that way. Saddly this is very true. There is a lack of good performance investigation

> I did not manage to find any good tutorial on debugging cache misses in that way. Saddly this is very true. There is a lack of good performance investigation information out there. And pref while very useful is not really a beginner tools. In your case, you want an "annotated" profile. Where perf will annotate the source code with the even, and basically pin-point which part of your code is producing the offending events (in this case the cache misses). If you really want to dig deep, i can't recommend intel Vtune. Only works with intel cpu (i think ?), but is the best tool in you want to understand performance at a deeper level.

vient 3y ago
The problem with cache misses specifically is that perf can't point an event to its exact location so you may get a high rate of cache misses on instruction that does not even work with memory, like jump, so you need to look what gets executed before that instruction and what looks like probable source there. I am interested if there are any more efficient approaches than this.
- soulbadguy 3y ago
  Perf can. But you need to massage it a bit. Out of the box , perf uses a bunch of generic performance counter which maybe not be the best. Intel cpu's have a a collection of "precisise" events which record the exact originating/offending instructions. If you use those it should fix your problem Pmu-tool by default uses precise events when available
  - vient 3y ago
    Oh, I did not know that perf by default may use some uncore events that are less precise than some Intel-specific events. Thanks for the info!
    - soulbadguy 3y ago
      You might want to look at https://icl.utk.edu/papi/ https://icl.utk.edu/papi/ . It's a generic library which abstract the details of specific cpu arch and aims to provide a single unify view of performance counters. I think somewhere in there you can see how perf translate counters to intel (or AMD) specific one.

vient 3y ago

The problem with cache misses specifically is that perf can't point an event to its exact location so you may get a high rate of cache misses on instruction that does not even work with memory, like jump, so you need to look what gets executed before that instruction and what looks like probable source there. I am interested if there are any more efficient approaches than this.

soulbadguy 3y ago
Perf can. But you need to massage it a bit. Out of the box , perf uses a bunch of generic performance counter which maybe not be the best. Intel cpu's have a a collection of "precisise" events which record the exact originating/offending instructions. If you use those it should fix your problem Pmu-tool by default uses precise events when available
- vient 3y ago
  Oh, I did not know that perf by default may use some uncore events that are less precise than some Intel-specific events. Thanks for the info!
  - soulbadguy 3y ago
    You might want to look at https://icl.utk.edu/papi/ https://icl.utk.edu/papi/ . It's a generic library which abstract the details of specific cpu arch and aims to provide a single unify view of performance counters. I think somewhere in there you can see how perf translate counters to intel (or AMD) specific one.