Jolsa Features Togle Event

Revision as of 18:12, 24 September 2013

Description

Example - using k(ret)probes

• Define toggle(on/off) events:

# perf probe -a fork_entry=do_fork
# perf probe -a fork_exit=do_fork%return

• Following record session samples only within do_fork function:

# perf record -g -e '{cycles,cache-misses}:k,probe:fork_entry/on=cycles/,probe:fork_exit/off=cycles/' \ 
  perf bench sched messaging

• Following stat session measure cycles within do_fork function:

# perf stat -e '{cycles,cache-misses}:k,probe:fork_entry/on=cycles/,probe:fork_exit/off=cycles/' \ 
  perf bench sched messaging

# Running sched/messaging benchmark...
# 20 sender and receiver processes per group
# 1 groups == 40 processes run

     Total time: 0.073 [sec]

 Performance counter stats for './perf bench sched messaging -g 1':

        20,935,464 cycles                    #    0.000 GHz
            18,897 cache-misses
                40 probe:fork_entry
                40 probe:fork_exit

       0.086319682 seconds time elapsed

Example - using u(ret)probes

• Sample program:

void krava(void)
{
        asm volatile ("nop; nop");
}

int main(void)
{
        krava();
        return 0;
}

• Define toggle(on/off) events:

# perf probe -x ./ex entry=krava
# perf probe -x ./ex exit=krava%return

• Following stat session measure instructions within krava function:

# perf stat -e instructions:u,probe_ex:entry/on=instructions/,probe_ex:exit/off=instructions/ ./ex

    Performance counter stats for './ex':

                 9 instructions:u            #    0.00  insns per cycle 
                 1 probe_ex:entry
                 1 probe_ex:exit

       0.000556743 seconds time elapsed

Following stat session measure cycles, instructions and cache-misses within krava function:

# perf stat -e '{cycles,instructions,cache-misses}:u,probe_ex:entry/on=cycles/,probe_ex:exit/off=cycles/' ./ex

     Performance counter stats for './ex':

           2,068 cycles                    #    0.000 GHz
               9 instructions              #    0.00  insns per cycle 
               0 cache-misses
               1 probe_ex:entry
               1 probe_ex:exit

     0.000557504 seconds time elapsed

Interface

Kernel

Perf Tool

Examples

Branch

• perf/core_toggle*