Thiemo Nagel wrote:
I've attached my script which does a stochastic comparison of power
consumption of two different configurations (currently with and without
ASPM)
Ooops. The script originally attached is broken, here comes a corrected
version...
BTW: My latest results with computer fully idle:
/sys/module/pcie_aspm/parameters/policy: powersave
cur: 6.17W, avg 10: 6.25W, tot. avg: 6.40W, stddev: 0.44W (n=261)
/sys/module/pcie_aspm/parameters/policy: performance
cur: 6.19W, avg 10: 6.25W, tot. avg: 6.41W, stddev: 0.52W (n=267)
So with my kernel and hardware, ASPM seems to have no effect.
Kind regards,
Thiemo
--
+-----------------------------------+--------------------------+
| Dipl.-Phys. Thiemo Nagel | |
| Technische Universitaet Muenchen | Room PH1 3276 |
| Physik-Department E18 | |
| James-Franck-Strasse | Phone +49 89 289-12379 |
| D-85747 Garching | Fax +49 89 289-12570 |
+-----------------------------------+--------------------------+
#! /usr/bin/perl
#
# stochastic power consumption comparison of two different configurations
use warnings;
use diagnostics;
use strict;
# commands to switch between two different states
my @cmd = ('echo performance > /sys/module/pcie_aspm/parameters/policy',
'echo powersave > /sys/module/pcie_aspm/parameters/policy');
#my @cmd = ('echo suspend > /sys/bus/usb/devices/5-6/power/level',
# 'echo auto > /sys/bus/usb/devices/5-6/power/level');
# maximal number of power readings between changes of states
my $interval = 5;
BEGIN {
my $oldC = 0;
my $oldV = 0;
sub getpower() {
my $C=0;
my $V=0;
my $p;
while (1) {
chomp($C = `cat /sys/class/power_supply/BAT0/current_now`);
chomp($V = `cat /sys/class/power_supply/BAT0/voltage_now`);
# avoid duplicate readings
if ($C == $oldC && $V == $oldV) {
sleep(1);
next;
}
$p = 1e-12 * $C * $V;
# avoid bad readings
if ($p < 3 || 20 < $p) {
print "Ignoring unreasonable reading: C=${C}uA, V=${V}uV\n";
sleep(1);
next;
}
last;
}
$oldC = $C;
$oldV = $V;
return $p;
}
}
my @list = (
[ (0., 0., 0., 0., 0., 0., 0., 0., 0., 0.) ],
[ (0., 0., 0., 0., 0., 0., 0., 0., 0., 0.) ]
);
my @sum = (0., 0.);
my @sum2 = (0., 0.);
my @n = (0, 0);
while (1) {
for (my $state = 0; $state < 2; $state++) {
print "State change: ", $cmd[$state], ": ", `$cmd[$state]`, "\n";
# randomize interval length to avoid unlucky synchronisations with
# periodic tasks being run on the machine
my $max = int(rand($interval))+1;
for (my $i = 0; $i <= $max; $i++) {
my $p = getpower();
next if $i==0;
push @{$list[$state]}, $p;
shift @{$list[$state]};
my $avg10 = 0.;
foreach my $v (@{$list[$state]}) { $avg10 += $v; }
$avg10 /= scalar @{$list[$state]};
$sum[$state] += $p;
$sum2[$state] += $p*$p;
$n[$state]++;
my $avg = $sum[$state] / $n[$state];
my $stddev = sqrt($sum2[$state] / $n[$state] - $avg*$avg);
# printf "Sum[%i]=%.2f\n", $state, $sum[$state];
printf "Status %i: cur: %.2fW, avg 10: %.2fW, ".
"tot. avg: %.2fW, stddev: %.2fW (n=%i)\n",
$state, $p, $avg10, $avg, $stddev, $n[$state];
}
}
}
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