# powertop numbers...

## eccerr0r

This might be a bit preliminary...

A while ago I was running eeebuntu on my eeePC.  For kicks I tried powertop on it, and actually got a fairly low number of interrupts per second.  However keeping eeebuntu up to date was a PITA as all my other machines were Gentoo.

So I switched over to Gentoo on my eeePC.

However my powertop numbers have went up.  Now I don't know if I have a fully apples-to-apples comparison here (same version of powertop, etc.) but what kinds of numbers are people getting in Gentoo with the current version of powertop in portage?

I couldn't get it below around 20-30 interrupts/second unless I completely disabled wireless and USB (not just leave them idle).  With everything disabled, making the machine quite useless, I got it down to less than 10 with Gnome running...

I recall eeebuntu with Gnome running easily got less to 10, without the work I needed to get Gentoo down that much...

Any ideas?  (or is this really diminishing returns on this?)

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## Ant P.

Depends on the kernel config, whether or not you have NO_HZ enabled, whether power management stuff is working correctly...

It should probably be lower than that though; with nothing running on my netbook I can get it down to 1.7 per second. We might be able to figure it out if you post `powertop -d` output here

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## eccerr0r

I think these are the conditions that match that of eeebuntu:

```
PowerTOP 1.13   (C) 2007 - 2010 Intel Corporation 

Collecting data for 15 seconds 

Your CPU supports the following C-states : C1 C2 C4 

Your BIOS reports the following C-states : C1 C2 C4 

Cn             Avg residency

C0 (cpu running)        ( 0.0%)

polling        0.0ms ( 0.0%)

C1 mwait     0.1ms ( 0.0%)

C2 mwait     0.3ms ( 0.1%)

C4 mwait    68.1ms (101.7%)

P-states (frequencies)

  1.60 Ghz     4.4%

  1333 Mhz     0.4%

  1067 Mhz     0.0%

   800 Mhz    95.2%

Wakeups-from-idle per second : 19.1   interval: 15.0s

no ACPI power usage estimate available

Top causes for wakeups:

  28.7% (  3.2)   swapper/0

  28.1% (  3.1)   swapper/1

  20.4% (  2.3)   [Rescheduling interrupts] <kernel IPI>

  15.0% (  1.7)   gnome-terminal

   1.8% (  0.2)   cc1

   1.8% (  0.2)   init

   1.8% (  0.2)   gnome-panel

   0.6% (  0.1)   gconfd-2

   0.6% (  0.1)   ssh-agent

   0.6% (  0.1)   gnome-power-man

   0.6% (  0.1)   gnome-settings-

An audio device is active 100.0% of the time:

hwC0D0 

Suggestion: increase the VM dirty writeback time from 5.00 to 15 seconds with:

  echo 1500 > /proc/sys/vm/dirty_writeback_centisecs 

This wakes the disk up less frequently for background VM activity

Suggestion: enable HD audio powersave mode by executing the following command:

   echo 1 > /sys/module/snd_hda_intel/parameters/power_save 

or by passing power_save=1 as module parameter.

Suggestion: Enable the CONFIG_INOTIFY kernel configuration option.

This option allows programs to wait for changes in files and directories

instead of having to poll for these changes

Recent USB suspend statistics

Active  Device name

  0.0%   USB device usb5 : UHCI Host Controller (Linux 3.2.1-gentoo-r2 uhci_hcd)

  0.0%   USB device usb4 : UHCI Host Controller (Linux 3.2.1-gentoo-r2 uhci_hcd)

  0.0%   USB device usb3 : UHCI Host Controller (Linux 3.2.1-gentoo-r2 uhci_hcd)

  0.0%   USB device usb2 : UHCI Host Controller (Linux 3.2.1-gentoo-r2 uhci_hcd)

  0.0%   USB device usb1 : EHCI Host Controller (Linux 3.2.1-gentoo-r2 ehci_hcd)

Runtime Device Power Management statistics

Active  Device name

100.0%   01:00.0 Ethernet controller: Atheros Communications Inc. AR8121/AR8113/AR8114 Gigabit or Fast Ethernet 

100.0%   00:1f.2 IDE interface: Intel Corporation 82801GBM/GHM (ICH7-M Family) SATA Controller [IDE mode] 

100.0%   00:1d.7 USB controller: Intel Corporation N10/ICH 7 Family USB2 EHCI Controller 

100.0%   00:1d.3 USB controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #4 

100.0%   00:1d.2 USB controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #3 

100.0%   00:1d.1 USB controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #2 

100.0%   00:1d.0 USB controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #1 

100.0%   00:1c.3 PCI bridge: Intel Corporation N10/ICH 7 Family PCI Express Port 4 

100.0%   00:1c.1 PCI bridge: Intel Corporation N10/ICH 7 Family PCI Express Port 2 

100.0%   00:1c.0 PCI bridge: Intel Corporation N10/ICH 7 Family PCI Express Port 1 

100.0%   00:1b.0 Audio device: Intel Corporation N10/ICH 7 Family High Definition Audio Controller 

100.0%   00:02.0 VGA compatible controller: Intel Corporation Mobile 945GME Express Integrated Graphics Controller 

100.0%   00:00.0 Host bridge: Intel Corporation Mobile 945GME Express Memory Controller Hub 

Devices without runtime PM

00:1f.0 ISA bridge: Intel Corporation 82801GBM (ICH7-M) LPC Interface Bridge 

00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge 

00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller 

Recent audio activity statistics

Active  Device name

100.0%   hwC0D0 

Recent SATA AHCI link activity statistics

Active   Partial   Slumber   Device name

```

I do have INOTIFY_USER set, I think 1.13 powertop doesn't know about it.  Not sure why [ath] doesn't show up in this run, but it should, it is the biggest contributer to interrupts during this snapshot.  I just get a lot of swapper and rescheduling...

The only way to get it down to less than 1 wakeup from idle is to ... not be idle...  I've seen it as low as 0.2 when doing heavy compiling jobs...

May need to run this again from boot so cc1 doesn't show up...

Hardware: Intel Atom N270, 32GB SSD, Atheros Wifi

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## Ant P.

powertop's fairly broken at times, I've seen it show wakeups from X when that isn't running. The inotify message seems to be invalid too.

I noticed it saying your audio card is active, you might want to check the powersave timeout for that in the kernel (default timeout is "0" == disabled)

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## eccerr0r

Oh weird, I just tried powertop on my core i7 (2700K) and got 9 wakeups/second without doing anything, so I guess it may just be specifically due to device interrupts versus software interrupts - the latter of which is what I'm most concerned with on my netbook (well... hardware interrupts do matter of course!).

Strange though when the i7 is idle, it's always in "turbo mode." but in C3.

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