Re: Powersaving Patch for NetworkManager

[Jan Kantert <jan-nm kantert net>]

James M. Leddy schrieb:
> drago01 wrote:
> > On Wed, Nov 26, 2008 at 1:59 PM, Alexander Sack <asac ubuntu com> wrote:
> > > On Tue, Nov 25, 2008 at 01:38:12PM +0100, Jan Kantert wrote:
> > > > Hi,
> > > >
> > > > according to powertop Network Manager wakes up my cpu about once every
> > > > two seconds. Thats does not sound much but on an idle desktop with 10
> > > > wake ups per seconds thats 5%. I wanted my laptop's cpu to stay longer
> > > > in sleepstates so I wrote a little patch (against trunk) to replace
> > > > g_timeout_add with g_timeout_add_seconds (where possible), which uses
> > > > more rough granularity. This helps to aggregate timeouts and will
> > > > statistically wake up the cpu less frequently.
> > > Sounds good. Curious, if you have collected data on how much of a
> > > powersaving win this patch brings?
> >
> > The patch itself won't save much power, but when other apps wake up
> > less often too the cpu will spend more time idle and therefore save
> > power.
>
> ?? - we should be able to quantify with powertop.  Even if it doesn't 
> save much power in the long run a wakeup once every 2 secconds (as 
> quoted) vs. a wakeup once every 10 is an %80 reduction in wakeups.
As I wrote: This patch helps to aggregate timeouts caused by glib
applications. The more glib applications you use, which use
g_timeout_add_seconds, the more wakeups will be saved. I patched some
more apps on my desktop to use g_timeout_add_seconds. In average it
helps to get my Thinkpad X61t from 10 wakeups to 8 wakeups, which is 20%
reduction.

Jan