[powerstation-owners] PowerStation Fans

[Pat Wall]

On Tue, 26 Jan 2010 02:42:40 +0100
Alexander Graf <agraf at suse.de> wrote:

> 
> On 26.01.2010, at 02:40, Stefan Nürnberger wrote:
> 
> > 
> > 
> > Am 26.01.10 02:23, schrieb Alexander Graf:
> >> 
> >> On 26.01.2010, at 02:12, Stefan Nürnberger wrote:
> >> 
> >>>> Hi All
> >>>> 
> >>>> I have a PowerStation running YDL 6.2 that overall I must say I
> >>>> am very happy with. If I could make it a bit quieter I would be
> >>>> even happier still ;-)
> >>>> 
> >>>> The fan noise is fairly loud on light desktop operation (e.g.
> >>>> browsing, emailing etc). Periodically and very suddenly the fans
> >>>> can spin up to maximum speed even if the PowerStation is idle
> >>>> and will usually return to normal speed within about 30 seconds.
> >>>> Is this type of fan activity normal for the PowerStation? -
> >>>> perhaps other users could confirm.
> >>>> 
> >>> 
> >>> Yes that's the normal behavior for the PowerStation.
> >>> 
> >>>> From reading the mailing list archives I see that the issue of
> >>>> noise levels has come up from time to time but there appears to
> >>>> be no solution. I was just wondering if anyone has ever found a
> >>>> way of controlling the fans?
> >>>> 
> >>> 
> >>> AFAIK the fans are controlled by the BMC. Communication with the
> >>> BMC should be possible through IPMI. I was able to obtain
> >>> readings from different temperature sensors this way, but did not
> >>> find any fan control mechanism. I also think that it would not be
> >>> very advisable to operate the CPUs at a higher temperature. The
> >>> better approach would be to utilize the power management features
> >>> of the processors. Unfortunately there was no cpufreq driver for
> >>> the 970MP last time I checked. There was only some basic support
> >>> for the 970FX in the linux kernel. It would be nice if someone
> >>> could look into that. There is no need for the processors to run
> >>> at full power when the system is idle. IIRC the 970MP has about
> >>> 15 different power modes. Switching off unused cores completely
> >>> would also be nice.
> >> 
> >> I haven't tried this yet, but while debugging a 970fx target I
> >> stumbled across this sysctl setting:
> >> 
> >> kernel.powersave-nap
> >> 
> >> which defaults to 0. When set to 1 (enabled), the kernel actually
> >> tells the cores to power down. With 0 (disabled) it just loops.
> >> 
> >> I guess it's worth a try ;-). Please tell me if it helps!
> >> 
> >> Alex
> > 
> > You are my personal hero! ;)
> > Works like a charm. The system has gone quiet in just a couple of
> > seconds. Thank you so much!
> 
> Yeah, same thing happened for my VM - suddenly it went from 100% host
> CPU usage to 0% ;-). I wonder why that option isn't enabled by
> default.
> 
> Either way, I'm glad I could help.
> 
> Alex

Hi Alex

You are rapidly gaining a fan club ;-)

I have just made the change myself and there is an immediate and
noticeable difference. It is such a pleasure!

I checked my dual-core Powermac and interestingly it's default setting
for kernel.powersave.nap is 1.

Thanks once again :-)

All the best



Pat