Linux C++: how to profile time wasted due to cache misses?

Question

I know that I can use gprof to benchmark my code.

However, I have this problem -- I have a smart pointer that has an extra level of indirection (think of it as a prox

Answer 1

Another tool for CPU performance counter-based profiling is oprofile. You can view its results using kcachegrind.

Answer 2

Linux supports with perf from 2.6.31 on. This allows you to do the following:

• compile your code with -g to have debug information included
• run your code e.g. using the last level cache misses counters: perf record -e LLC-loads,LLC-load-misses yourExecutable
• run perf report
  • after acknowledging the initial message, select the LLC-load-misses line,
  • then e.g. the first function and
  • then annotate. You should see the lines (in assembly code, surrounded by the the original source code) and a number indicating what fraction of last level cache misses for the lines where cache misses occurred.

Answer 3

Here's kind of a general answer.

For example, if your program is spending, say, 50% of it's time in cache misses, then 50% of the time when you pause it the program counter will be at the exact locations where it is waiting for the memory fetches that are causing the cache misses.