[Freeipmi-devel] RE: ipmi-dcmi testing results

[Al Chu]

Hey Holger,

> Get power reading command reports only if the system is currently
> measuring the power (most DCMI with power management systems will
> report true). The get power limit reports the current settings and if
> (the) power limit is active. So our current interpretation of
> completion code 0x80 is a minor re-wording of 'No Set Power Limit' as
> 'No Power Limit Set' - and is used to report a deactivated power
> limit. 

I see.  I guess another way to view it is if the sentence "No Set Power
Limit" is interpreted as:

No "Set Power Limit"

vs.

No set "Power Limit"

If it is the later, then I misinterpreted.

> Interesting to see, that in the end dcmitool and the DCTS behave
> differently. 

If Fujitsu has interpreted this way (partially b/c of DCTS), I think
it's a good chance other companies have interpreted it this way too.  So
how about I make a special case.  If you are configuring w/
set-power-limit, but you can't call get-power-limit, then the user must
give values for all input fields (exception action, limit, time limit,
etc.).  

> Again, thanks for the feedback

No problem at all.

> and maybe Intel can provide some more clarification someday.

Ultimately, that's probably what we'll need to wait for.  I'll ping
someone from Intel I've spoken with before, maybe he can offer some
insight.

Al

On Wed, 2009-12-16 at 11:39 +0100, Liebig, Holger wrote:
> Hi Al,
> > 
> > > Some more testing with the 0.8.2beta3 shows, that after 
> > deactivating 
> > > the power limit, the --get-power-limit is choking on the completion 
> > > code 0x80 (Power Limit not active), also a --set-power-limit 
> > > --power-limit-requested=350 is reading the current setting before 
> > > modifying the settings and also fails when the power limit is 
> > > disabled.  The typical use case is more like configure some/all 
> > > settings, and then activate the power limit.
> > 
> > My copy of the spec says that the completion code is "No set 
> > power limit" (and don't see a change in the errata), which I 
> > interpret to mean that set power limit isn't supported?? 
> > Skimming through the dcmitool code, it seems they do the same 
> > thing as me.  They call the 'get' first then 'set' later.  I 
> > guess I don't quite understand how you/Fujitsu are reading 
> > the spec differently than I am.
> 
> That's quite an interesting discussion and good feedback.
> 
> Reading and making sense of the specs is not always easy and for non
> native speakers even a little bit harder ;) We've had already
> implemented a Power Monitoring and Control Mechanism when DCMI came
> out, so we kind of glue'd them together. One problem is, that DCMI
> knows and supports only an (enforced) Power Limit, while there might
> be other use cases for other customers, for instance scheduled
> switching between power modi.
> 
> Regarding the Get Power Limit Command completion code:
> We've interpreted it the following way: The spec reads completion code
> 00 means 'Power Limit (is) Active'. And there is a command to activate
> or deactivate the power limit. So, how does one know if the limit is
> currently activated or deactivated? Unfortunately there is no flag
> defined in the DCMI capabilities other than the global Power
> Management is supported flag and no differentiation is made between
> systems which support only Power Measurement & reporting (basically a
> sensor in the system) and systems which do support enforcing a power
> limit which requires hard or software.
> 
> Get power reading command reports only if the system is currently
> measuring the power (most DCMI with power management systems will
> report true). The get power limit reports the current settings and if
> (the) power limit is active. So our current interpretation of
> completion code 0x80 is a minor re-wording of 'No Set Power Limit' as
> 'No Power Limit Set' - and is used to report a deactivated power
> limit. 
> Of cause, this is open to discussion and any feedback is welcome.
> 
> Also, the major source/influence/backup for the current implementation
> was the DCMI conformance test suite which came out earlier this year.
> In TestGetPwrLimit() any completion code different from 0x00 or 0x80
> is interpreted as Power Limit not supported. And in
> TestSetPowerLimit(), before setting a power limit the power limit is
> actually deactivated. Interesting to see, that in the end dcmitool and
> the DCTS behave differently. 
> 
> One issue with the DCTS is that it cross checks the 'Power Measurement
> active' from the get power reading command with the 'Power Limit
> Active' from the get power limit command, which IMHO is comparing
> apples with oranges.
> 
> Again, thanks for the feedback and maybe Intel can provide some more 
> clarification someday.
> 
> Holger
-- 
Albert Chu
address@hidden
Computer Scientist
High Performance Systems Division
Lawrence Livermore National Laboratory