Azimout's Linux weblog


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I installed powertop:

PowerTOP is a Linux tool that finds the software component(s) that make your laptop use more power than necessary while it is idle. As of Linux kernel
version 2.6.21, the kernel no longer has a fixed 1000Hz timer tick. This will
(in theory) give a huge power savings because the CPU stays in low power mode for longer periods of time during system idle.
However… there are many things that can ruin the party, both inside the
kernel and in userspace. PowerTOP combines various sources of information from the kernel into one convenient screen so that you can see how well your system is doing, and which components are the biggest problem.

It monitors the reasons that wake the processor up from idle mode and gives suggestions. For most of them you get the possibility to press a button and make the change… The only one where I couldn’t just press a button was “Enable the CONFIG_NO_HZ kernel configuration option.”, which apparently needs kernel re-compiling… It is the famous tickless kernel feature. I have kernel 2.6.22-14-386… Should I upgrade my kernel, or wait for Hardy (2.6.24)?


Written by azimout

11/03/2008 at 10:36

Posted in Opinion

8 Responses

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  1. it askes me:
    -to enable usb autosuspend by adding usbcore.autosuspend=1 to the kernel command line in the grub config
    -to mount filesystems with the noatime option by running mount -o remount,noatime /
    -to enable ac97 powersave by running: echo 1 > /sys/module/snd_ac97_codec/parameters/power_save
    or by passing power_save=1 as module parameter.
    -increase the VM dirty writeback time from 5.00 to 15 seconds with: echo 1500 > /proc/sys/vm/dirty_writeback_centisecs


    13/03/2008 at 17:53

  2. this is a nice article about powertop, which I just discovered is part of Intel’s lesswatts project!


    13/03/2008 at 18:01

  3. the usbcore.autosuspend=1 kernel option is not recognized and ignored:
    Unknown boot option `usbcore.autosuspend=1': ignoring
    but cat /sys/module/usbcore/parameters/autosuspend answers 2, which means usb autosuspend is enabled…


    14/03/2008 at 14:11

  4. cat /sys/bus/usb/devices/*/power/autosuspend gives me:
    however powertop keeps asking me to enable it. If I press u in powertop, cat /sys/bus/usb/devices/*/power/autosuspend now gives me:


    14/03/2008 at 14:38

  5. It is filed as a bug in Launchpad, but in the discussion it is unclear what the correct solution is


    14/03/2008 at 14:41

  6. I reported my first Ubuntu bug (actually, it’s related to Intel’s powertop utility) here:


    14/04/2008 at 13:33

  7. Another very good tool by intel, this time to measure latencies…


    18/04/2008 at 08:41

  8. Why does powertop say “no ACPI power usage estimate available” when your laptop is connected to the charger?


    05/05/2008 at 08:43

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