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@qqibrow @agentzh @kingluo
executable file 308 lines (248 sloc) 6.76 KB
#!/usr/bin/env perl
# Copyright (C) Yichun Zhang (agentzh)
# Thanks Brendan Gregg for the inspiration given here:
# http://dtrace.org/blogs/brendan/2011/07/08/off-cpu-performance-analysis/
use 5.006001;
use strict;
use warnings;
use Getopt::Long qw( GetOptions );
GetOptions("a=s", \(my $stap_args),
"d", \(my $dump_src),
"distr", \(my $check_distr),
"h", \(my $help),
"k", \(my $check_kernel),
"l=i", \(my $limit),
"min=i", \(my $min_elapsed),
"p=i", \(my $pid),
"t=i", \(my $time),
"u", \(my $check_user))
or die usage();
if ($help) {
print usage();
exit;
}
if (!defined $min_elapsed) {
$min_elapsed = 4;
}
if (!defined $pid) {
die "No process pid specified by the -p option.\n";
}
my $condition = "pid() == target()";
if (!defined $time) {
die "No -t <seconds> option specified.\n";
}
if (!defined $limit) {
$limit = 1024;
}
if (!defined $stap_args) {
$stap_args = '';
}
if ($stap_args !~ /(?:^|\s)-D\s*MAXACTION=/) {
$stap_args .= " -DMAXACTION=100000";
}
if ($stap_args !~ /(?:^|\s)-D\s*MAXMAPENTRIES=/) {
$stap_args .= " -DMAXMAPENTRIES=3000";
}
if ($stap_args !~ /(?:^|\s)-D\s*MAXBACKTRACE=/) {
$stap_args .= " -DMAXBACKTRACE=200";
}
if ($stap_args !~ /(?:^|\s)-D\s*MAXSTRINGLEN=2048/) {
$stap_args .= " -DMAXSTRINGLEN=2048";
}
$stap_args .= " -DSTP_NO_OVERLOAD";
if ($^O ne 'linux') {
die "Only linux is supported but I am on $^O.\n";
}
my $exec_file = "/proc/$pid/exe";
if (!-f $exec_file) {
die "User process $pid is not running or ",
"you do not have enough permissions.\n";
}
my $exec_path = readlink $exec_file;
my $ver = `stap --version 2>&1`;
if (!defined $ver) {
die "Systemtap not installed or its \"stap\" utility is not visible to the PATH environment: $!\n";
}
if ($ver =~ /version\s+(\d+\.\d+)/i) {
my $v = $1;
if ($v < 2.1) {
die "ERROR: at least systemtap 2.1 is required but found $v\n";
}
} else {
die "ERROR: unknown version of systemtap:\n$ver\n";
}
my $preamble = <<_EOC_;
global quit = 0;
global found
probe begin {
warn(sprintf("Tracing %d ($exec_path)...\\n", target()))
}
_EOC_
my $postamble = <<_EOC_;
probe timer.s($time) {
if (!found) {
warn("No backtraces found. Quitting now...\\n")
exit()
} else {
warn("Time's up. Quitting now...(it may take a while)\\n")
quit = 1
}
}
_EOC_
my $stap_src;
my $d_so_args = '';
if ($check_distr) {
$stap_src = <<_EOC_;
global start_time
global elapsed_times
$preamble
probe end {
if (!found) {
println("\\nNo samples found yet.")
} else {
println("=== Off-CPU time distribution (in us) ===")
printf("min/avg/max: %d/%d/%d\\n",
\@min(elapsed_times), \@avg(elapsed_times), \@max(elapsed_times))
println(\@hist_log(elapsed_times))
}
}
probe scheduler.cpu_off {
if ($condition) {
if (!quit) {
start_time[tid()] = gettimeofday_us()
} else {
exit()
}
}
}
probe scheduler.cpu_on {
if ($condition && !quit) {
t = tid()
begin = start_time[t]
if (begin > 0) {
elapsed = gettimeofday_us() - begin
if (elapsed >= $min_elapsed) {
found = 1
elapsed_times <<< elapsed
}
delete start_time[t]
}
}
}
probe timer.s($time) {
println("Exiting...Please wait...")
quit = 1
}
_EOC_
} else {
# for sampling backtraces
my ($gen_bt_code, $print_bt_code);
if ($check_kernel) {
if ($check_user) {
$gen_bt_code = "backtrace(), ubacktrace()";
$print_bt_code = <<_EOC_;
foreach ([kbt, ubt] in bts- limit $limit) {
print_stack(kbt)
print_ustack(ubt)
printf("\\t%d\\n", \@sum(bts[kbt, ubt]))
}
_EOC_
} else {
$gen_bt_code = "backtrace()";
$print_bt_code = <<_EOC_;
foreach (bt in bts- limit $limit) {
print_stack(bt)
printf("\\t%d\\n", \@sum(bts[bt]))
}
_EOC_
}
} else {
$gen_bt_code = "ubacktrace()";
$print_bt_code = <<_EOC_;
foreach (bt in bts- limit $limit) {
print_ustack(bt)
printf("\\t%d\\n", \@sum(bts[bt]))
}
_EOC_
}
$stap_src = <<_EOC_;
global bts
global start_time
$preamble
probe scheduler.cpu_off {
if ($condition) {
if (!quit) {
start_time[tid()] = gettimeofday_us()
} else {
$print_bt_code
exit()
}
}
}
probe scheduler.cpu_on {
if ($condition && !quit) {
t = tid()
begin = start_time[t]
if (begin > 0) {
elapsed = gettimeofday_us() - begin
if (elapsed >= $min_elapsed) {
bts[$gen_bt_code] <<< elapsed
found = 1
}
delete start_time[t]
}
}
}
$postamble
_EOC_
my %so_files;
{
my $maps_file = "/proc/$pid/maps";
open my $in, $maps_file
or die "Cannot open $maps_file for reading: $!\n";
while (<$in>) {
if (/\s+(\/\S+\.so(?:\.\S+)?)$/) {
if (!exists $so_files{$1}) {
$so_files{$1} = 1;
#warn $1, "\n";
}
}
}
close $in;
}
if (%so_files) {
$d_so_args = join " ", map { "-d $_" } sort keys %so_files;
}
}
if ($dump_src) {
print $stap_src;
exit;
}
#warn "$d_so_args\n";
open my $in, "|stap --skip-badvars --all-modules -x $pid -d '$exec_path' --ldd $d_so_args $stap_args -"
or die "Cannot run stap: $!\n";
print $in $stap_src;
close $in;
sub usage {
return <<'_EOC_';
Usage:
sample-bt-off-cpu [optoins]
Options:
-a <args> Pass extra arguments to the stap utility.
-d Dump out the systemtap script source.
--distr Analyze the distribution of the elapsed off-CPU times only.
-h Print this usage.
-k Analyze kernelspace backtraces.
-l <count> Only output <count> most frenquent backtrace samples.
(Default to 1024)
--min=<us> Minimal elapsed off-CPU time to be tracked.
(Default to 4us)
-p <pid> Specify the user process pid.
-t <seconds> Specify the number of seconds for sampling.
-u Analyze userspace backtraces.
Examples:
sample-bt-off-cpu -p 12345 -t 10
sample-bt-off-cpu -p 12345 -t 5 -a '-DMAXACTION=100000'
sample-bt-off-cpu --distr -p 12345 -t 10 --min=1
_EOC_
}
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