CODEWITHSUNDEEP
linuxperflikwid
user2548418
user2548418

Reputation: 1571

perf stat for part of program

Is it possible with perf to collect hardware counter statistics for only part of a program's execution? If so, how?

likwid offers the feature of being able to define named regions, but it would be great if this was possible on systems with just perf installed.

Some previous questions have returned relevant answers, but there are still some shortcomings:

Upvotes: 14

Views: 4915

Answers (2)

Mohamed Husain
Mohamed Husain

Reputation: 131

Spawn a child process to run perf stat.
Attach perf stat to the parent.
Kill the child process from parent as and when required.

#include <unistd.h>
#include <stdio.h>
#include <signal.h>

int main()
{

    int pid= getpid();
    int cpid = fork();


    if( cpid == 0)
    {
        // child process .  Run your perf stat
        char buf[50];
        sprintf(buf, "perf stat -p %d   > stat.log 2>&1",pid);
        execl("/bin/sh", "sh", "-c", buf, NULL);

    }
    else
    {
        // set the child the leader of its process group
        setpgid(cpid, 0);

        //////////////////////////////////////////////
        // part of program you wanted to perf stat
        sleep(3);
        ////////////////////////////////////////////////


        ////////////////////////////////////////////////////////////////
        // stop perf stat by killing child process and all its descendants(sh, perf stat etc )
        kill(-cpid, SIGINT);
        ////////////////////////////////////////////////////////////////////


        // rest of the program
        sleep(2);
     }
}

Upvotes: 13

BeeOnRope
BeeOnRope

Reputation: 65046

You could use libpfc or jevents both of which are Linux-compatible libraries that allow programming and reading of performance counters via rdpmc at arbitrary points in the userland program.

This won't help directly with your request to specify events on the command line, but you could back something together perhaps based on the ocperf.py code, or libpfm4.

Upvotes: 1

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