Cache Hit/Miss for a value in C/C++ Program

Question

This is my requirement, I know that certain algorithms makes good use of Cache, some do not, some do more I/O than others on particular data set, etc. I would like to see and analyze that happening myself.

So I was wondering if there was a way I could know how a certain memory/variable is read, i.e. is it from cache, or was there a cache miss. Further if there was a page fault while retrieving this value etc.

Thanks a lot!

Answer 1

If you really want to know when your caches are hitting/missing, modern processors have performance counters that you can use for exactly this purpose. I have used them extensively for academic research. The easiest way to use them is through perfmon2. Perfmon2 has both a library you can link into your program or a stand-alone program that will monitor an existing program. For example, here's the stand-alone program recording all level 1 data cache read requests and misses:

pfmon -eL1D_CACHE_LD:MESI,L1D_CACHE_LD:I_STATE your_program

For reference, Appendix A of this document (PDF) lists Intel's documentation on what hardware counters are available.

Answer 2

I would try using the valgrind cachegrind tool, it can print out annotated source lines with the number of hits/misses in which cache for that line.