powerd effectiveness

[Bruno Ducrot]

On Thu, Jan 12, 2006 at 03:17:19PM -0500, Mike Jakubik wrote:
> Victor Balada Diaz wrote:
> >I know that this is not what you're asking for, but anyway:
> >
> >You should try sysutils/fvcool, it will reduce de heat a lot and the
> >performance will not suffer.
> >  
> ---
> ===> WARNING
> 
>    This software can have a negative impact on system stability. In
>    particular while doing heavy duty work such as encoding music,
>    under certain conditions the system can freeze.
> 
>    Don't use this software in production or mission-critical
>    environments!
> 
>    Also note that this software is supposed to be used with AMD
>    Athlon (XP) an AMD Duron processors only.

I don't think the latest statement is true.  The Athlon 4 family use the
same kind of power saving technology than the other version of the
Athlon XP.
Problem is that the Athlon 4 do have some annoying erratum that prevent it
to use them for this purpose if a specific MSR is not set correctly
by the BIOS, and when there is a half-frequency multiplier used.
If an half-frequency multiplier is in use, it's possible the BIOS
configured the northbridge such that the disconnect bit is not set, and
then asserting the STPCLK# to the processor prevent it to go into a
lower power state.

see
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/23614.pdf

errata #11 "PLL Overshoot on Wake-Up from disconnect causes
Auto-Compensation Circuit to Fail"

errata #14 "Processors with Half-Frequency Multipliers May Hang Upon
Wake-up from disconnect"

If the latter, it may be possible to put another multiplier by a bios
option.  For the former, well it may be possible the BIOS do not
set correctly the CLK_CTL MSR.

In order to check the value put to this MSR, I just written a dummy
module here:

http://people.freebsd.org/~bruno/read_clk_ctl.tar.bz2

If a value like that one:
ctl_ctl = 60031223 (or something like such) then it's likely the bios is
not upgraded or do not include some workaround.  If something like that
20031223 then it's likely your BIOS do have this kind of workaround
enabled already.


-- 
Bruno Ducrot

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.