PowerTOP tool released; time to fix the wasted laptop power on fedora?

Martin Sourada martin.sourada at seznam.cz
Sun May 13 19:37:35 UTC 2007

Arjan van de Ven wrote:
> Hi,
> some of you already know that I've been working on getting Linux (and
> Fedora) to be a lot better about power usage on laptops by avoiding
> spurious wakeups and context switches and such (look at the "wakeup" bug
> in fedora bugzilla ;).
> As part of my job at Intel I've now released a user friendly tool that
> allows everyone that uses it to see what the biggest problems on their
> own laptop are... The results internally to Intel have been really good;
> several people gained an hour of battery just by using the tool and
> getting rid of (or fixing) 'broken' applications.
> PowerTOP can be downloaded from http://www.linuxpowertop.org
> for completeness I've attached the full announcement text I used in
> other places below. I hope that enough people will use it and report /
> fix issues in software so that the whole Linux experience on laptops
> will be a lot better in a few months..
> ----------------------
> What's eating the battery life of my laptop? Why isn't it many more
> hours? Which software component causes the most power to be burned?
> These are important questions without a good answer... until now.
> The Linux 2.6.21 kernel introduces the so called tickless-idle
> feature. This feature allows the processor to be really idle for long
> periods of time, rather than having to wake up every millisecond for
> the timer tick. Current processors save a lot of power if they are
> idle for long periods, which translates into a longer battery life for
> your laptop, or a lower energy bill for your datacenter. However, a
> Linux system consists of more software than just the kernel, and there
> are many tunables involved. It's not easy to see what is going on, and
> as a result the behavior is sometimes far from optimal, and a lot of
> power is wasted.
> Intel is proud to announce the PowerTOP tool
> (http://www.linuxpowertop.org), a program that collects the various
> pieces of information from your system and presents an overview of how
> well your laptop is doing in terms of power savings. In addition,
> PowerTOP will provide an indication of which tunables and software
> components are the biggest offenders in slurping up your battery time.
> PowerTOP will update it's display frequently so that you can directly
> see the impact of any changes you are making.
> A typical Linux distribution has many components that wake the
> processor up frequently for no good reason. In our testing with
> PowerTOP, we have seen many cases where with some simple fixes, the
> battery life of typical laptops was increased by one hour or more!
> We are providing fixes for several of the issues we identified, and we
> encourage the Linux community to help us in this quest to get the
> maximum battery life out of your (hopefully Intel based) laptops. Try
> the PowerTOP tool, join the mailing list or the IRC channel and
> provide feedback, problem reports or fixes!
> Website:      http://www.linuxpowertop.org
> IRC:          irc.oftc.net    #powertop channel
> Mailing list: http://www.bughost.org/mailman/listinfo/power

Cool thing, just tried it on rawhide with the not-so-unexpected result where the 
top is liferea and epiphany followed by usb, XOrg and eth0.... But what I didn't 
expect was the power usage and count of wakeups:
Wakeups-from-idle per second :  413.0
Power usage (ACPI estimate) :   1.1 W (2.4 hours left)

1.1 W? That is really low IMO... Really, really interesting. Hope this tool 
helps to improve linux powersaving capabilities in the future. Keep the good 
work :-)


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