why counter is very big?

[lslhcqy123]

Hey.i want to ask a question about the value of cpu counter.
First,what's the meaning of cpu counter?
Second,why the cpu counter is so big?
the command like: ./profiler.sh -e cpu xxx
I use async-profiler v2.8.3 to monitor a simple java program of cpu event,and i got very big counter.
So i add logs in code like follow in perfEvents_linux.cpp:

void PerfEvents::signalHandler(int signo, siginfo_t* siginfo, void* ucontext) {
    if (siginfo->si_code <= 0) {
        // Looks like an external signal; don't treat as a profiling event
        return;
    }

    if (_enabled) {
        u64 counter = readCounter(siginfo, ucontext);
        ExecutionEvent event;
        printf("enter PerfEvents::signalHandler,counter:%ld\n",counter);
        Profiler::instance()->recordSample(ucontext, counter, PERF_SAMPLE, &event);
    } else {
        resetBuffer(OS::threadId());
    }

    ioctl(siginfo->si_fd, PERF_EVENT_IOC_RESET, 0);
    ioctl(siginfo->si_fd, PERF_EVENT_IOC_REFRESH, 1);
}

And i got the log like follows:
"enter PerfEvents::signalHandler,counter:10140865".
I am really confused why the counter is so big when the siginfo is 0.
Any reply is grateful.

[apangin]

what's the meaning of cpu counter

CPU time in nanoseconds

why the cpu counter is so big?

10140865 nanoseconds = 10.14 milliseconds.

The default profiling interval is 10 ms; this means, one CPU sample is generated approximately for every 10 ms of CPU time spent in one thread. The counter value reflects the time spent since the last sample - in your example, it expectedly matches the default profiling interval.

[lslhcqy123]

Thank you,I got it !

[lslhcqy123]

One more question please:
If i choose --alloc 32k, what's the unit of counter,byte or kbyte? @apangin

[apangin]

In allocation profile, counter is always in bytes.

[lslhcqy123]

ok,thank you!