Linux get CPU cache hit ratio

Question

AFAIK a lot of modern CPUs have counters for memory cache misses/hits.

Is there an API/program which can query this? Is there a way to reset the counters?

I'm interested in any generic or CPU specific program.

Note: I'm aware of cachegrind, but that's a simulation, and not the actual CPU counter.

Answer 1

Alright, I plundered some more resources and appears like for CPU cache hit/miss counters, we have to go for individual process or pid or tid based tracing. That is, in other words, perf and oprofile.

For example perf stat gives this.

 Performance counter stats for 'ls':

      3.905621 task-clock                #    0.831 CPUs utilized
             1 context-switches          #    0.000 M/sec
             0 CPU-migrations            #    0.000 M/sec
           267 page-faults               #    0.068 M/sec
       379,003 cycles                    #    0.097 GHz                     [24.55%]
     1,332,419 stalled-cycles-frontend   #  351.56% frontend cycles idle    [36.65%]
 <not counted> stalled-cycles-backend
       833,177 instructions              #    2.20  insns per cycle
                                         #    1.60  stalled cycles per insn
       580,745 branches                  #  148.695 M/sec                   [95.65%]
        37,799 branch-misses             #    6.51% of all branches         [71.09%]

   0.004697863 seconds time elapsed

Oprofile gives the similar output but perf is pretty awesome, imo.

Other thing is, for memory banks, numastat gives you another level of detail.

$ numastat
                       node0
numa_hit                74263001
numa_miss                      0
numa_foreign                   0
interleave_hit             15459
local_node              74263001
other_node                     0

Yeah, this system is a 1 node system.

Answer 2

In this question/answer they talk about linux tools for profiling cache-miss:

perf:

$ perf stat ./yourapp
$ perf stat -B dd if=/dev/zero of=/dev/null count=1000000

valgrind:

$ valgrind ./yourapp

but also time that counts page faults in theory:

$ time -v YourProgram.exe

on my system it does not accept -v flag, I must check why