who-ctxswitch-process

#! /usr/bin/env perl

# Copyright (C) YangBingwu (detailyang)

use 5.0006001;
use strict;
use warnings;
use Getopt::Std qw ( getopts );

sub usage();

my %opts;

getopts("hda:t:p:", \%opts) or die usage();

if ($opts{h}) {
    print usage();
    exit;
}

my $stap_args = $opts{a} || '';
getopts('dp:t:', \%opts) or die usage();

my $time = $opts{t} || 10000;
if ($time !~ /^\d+$/) {
   die "Bad -t options value \"$time\": not look like time";
}

my $pid = $opts{p} || "";
if ($pid !~ /^\d+$/) {
    die "Bad -p options value \"$pid\": not look like pid";
}

my $preamble = <<_EOC_;
probe begin {
    printf("Collecting who is context switch $pid \\r\\n");
}
_EOC_

my $stap_src = <<_EOC_;
$preamble

function state_calc:string(state:long) {
    if(state == 0)
    status = "R"
    if(state == 1)
    status = "S"
    if(state == 2)
    status = "D"
    if(state == 4)
    status = "T"
    if(state == 8)
    status = "T"
    if(state == 16)
    status = "Z"
    if(state == 32)
    status = "EXIT_DEAD"

    return status
}

probe scheduler.ctxswitch
{
    if (next_pid != $pid && prev_pid != $pid) next

    prev = sprintf("%-16s(%5d)<%s>",
        prev_task_name,
        prev_pid, state_calc(prevtsk_state)
            )
    _next = sprintf("%-16s(%5d)<%s>",
        next_task_name,
        next_pid,
        state_calc(nexttsk_state))
    printf("[%d] %-36s => %-36s\\n",
        task_cpu(prev_task),
            prev, _next)
}

probe timer.ms($time) {
    exit()
}
_EOC_

if ($opts{d}) {
    print $stap_src;
    exit();
}

open my $in, "| stap $stap_args --skip-badvars -";

print $in $stap_src;

close $in;


sub usage() {
    return <<'_EOC_';
Usage:
    who-ctxswitch-process [optoins]
Options:
    -a <args>           Pass extra arguments to the stap utility.
    -t <time>(ms)       Time(ms) to execute.
    -p <pid>            Specify the user process pid.
    -d                  Dump out the systemtap script source.
    -h                  Print this usage.
Examples:
    who-ctxswitch-process -t 10000 -p 1234
_EOC_
}