It crossed my mind while load testing some scheduler tunable settings
that completely subjective monitoring of X jerkiness perhaps wasn't
the most scientific way of measuring the interactive impact of the
tunables. I'm no Evil Scientist, but I whipped up a perl script that
I think accomplishes something close to capturing those statistics.
It captures 1000 samples of what should be a precise .2 second delay
(on an idle system it is, with a tiny bit of noise).
Here's the script, along with some output produced while the system
was under considerable load (around 13). Would something like this be
worth developing further to help rigorously measure the interactive
impact of the tunables? Or is there a flaw in the approach? (Jokes
about Perl are considered below the belt...)
---scott
#!/usr/bin/perl
use strict;
use warnings;
use Time::HiRes qw/sleep time/;
my %pause = ();
for (my $x = 0; $x < 1000; $x++) {
my $start = time();
sleep(.2);
my $stop = time();
my $elapsed = $stop - $start;
$pause{sprintf('%01.3f', $elapsed)}++;
}
foreach (sort(keys(%pause))) {
print "$_: $pause{$_}\n";
}
exit 0;
Sample output
time ./int_resp_timer.pl
0.192: 1
0.199: 1
0.200: 10
0.201: 201
0.202: 53
0.203: 25
0.204: 22
0.205: 21
0.206: 34
0.207: 29
0.208: 29
0.209: 100
0.210: 250
0.211: 120
0.212: 35
0.213: 16
0.214: 17
0.215: 14
0.216: 9
0.217: 1
0.218: 3
0.219: 3
0.220: 1
0.222: 1
0.233: 1
0.303: 1
0.304: 1
0.385: 1
real 3m28.568s
user 0m0.329s
sys 0m1.260s
That sounds pretty reasonable; it might be interesting if it also touched
quite a bit of memory each iteration too.
Andrew
--On Thursday, December 26, 2002 19:39:09 -0600 scott thomason
<[email protected]> wrote:
> It crossed my mind while load testing some scheduler tunable settings
> that completely subjective monitoring of X jerkiness perhaps wasn't
> the most scientific way of measuring the interactive impact of the
> tunables. I'm no Evil Scientist, but I whipped up a perl script that
> I think accomplishes something close to capturing those statistics.
> It captures 1000 samples of what should be a precise .2 second delay
> (on an idle system it is, with a tiny bit of noise).
>
> Here's the script, along with some output produced while the system
> was under considerable load (around 13). Would something like this be
> worth developing further to help rigorously measure the interactive
> impact of the tunables? Or is there a flaw in the approach? (Jokes
> about Perl are considered below the belt...)
> ---scott
>
>
># !/usr/bin/perl
>
> use strict;
> use warnings;
>
> use Time::HiRes qw/sleep time/;
>
> my %pause = ();
>
> for (my $x = 0; $x < 1000; $x++) {
> my $start = time();
> sleep(.2);
> my $stop = time();
> my $elapsed = $stop - $start;
>
> $pause{sprintf('%01.3f', $elapsed)}++;
> }
>
> foreach (sort(keys(%pause))) {
> print "$_: $pause{$_}\n";
> }
>
> exit 0;
>
>
> Sample output
>
> time ./int_resp_timer.pl
> 0.192: 1
> 0.199: 1
> 0.200: 10
> 0.201: 201
> 0.202: 53
> 0.203: 25
> 0.204: 22
> 0.205: 21
> 0.206: 34
> 0.207: 29
> 0.208: 29
> 0.209: 100
> 0.210: 250
> 0.211: 120
> 0.212: 35
> 0.213: 16
> 0.214: 17
> 0.215: 14
> 0.216: 9
> 0.217: 1
> 0.218: 3
> 0.219: 3
> 0.220: 1
> 0.222: 1
> 0.233: 1
> 0.303: 1
> 0.304: 1
> 0.385: 1
>
> real 3m28.568s
> user 0m0.329s
> sys 0m1.260s
>
> -
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