Re: [Freeipmi-users] power readings

[Al Chu]

Hi Ken,

The short answer is depends heavily on your motherboard and the way you
are getting the data.

For example, if you are doing it via Intel power node manager

> /usr/sbin/ipmi-oem intelnm get-node-manager-statistics
Current Power                                 : 490 Watts
Minimum Power                                 : 36 Watts
Maximum Power                                 : 681 Watts
Average Power                                 : 497 Watts
Power Statistics Reporting Period             : 1 seconds
<snip>

I think the output speaks for itself, there is instantaneous and averages.

If it's DCMI

> /usr/sbin/ipmi-dcmi --get-system-power-statistics
Current Power                        : 246 Watts
Minimum Power over sampling duration : 246 watts
Maximum Power over sampling duration : 246 watts
Average Power over sampling duration : 246 watts
Time Stamp                           : 05/15/2012 - 18:31:24
Statistics reporting time period     : 69380 milliseconds
Power Measurement                    : Not Available

likewise instantaneous & averages.  Here's a specific one to Dell

> /usr/sbin/ipmi-oem dell get-power-consumption-data
Cumulative Energy Start Time : 09/10/09 - 16:07:49
Cumulative Energy            : 199.93
kWh Peak Amp Time            : 04/27/11 - 19:18:27
Peak Amp                     : 0.90 A
Peak Watt Time               : 04/27/11 - 23:10:10
Peak Watt                    : 197 W

It appears this is definitely an averaging one.

If you are getting it via ipmi-sensors, it's almost definitely
instantenous.

Universally, I would say they are never blocking calls.

The interval is usually read through another one of the options
available in the tool/tools or listed right there (in several of the
cases above).  Don't remember options off the top of my head, but
hopefully some trial & error with the options listed in the manpage will
be enough.

Hope that helps,

Al

On Mon, 2014-01-13 at 15:37 +0000, Ken O'Brien wrote:
> Dear freeipmi devs,
> 
> I would like to programmatically read power consumption using freeipmi.
> I am wondering, how frequently can I poll using ipmi to read this value.
> More so, how often is this value updated in hardware. Is it a blocking
> call? 
> 
> The value returned is in units of watts. Is this an instantaneous value,
> or the average value over a set interval? If an interval, how do I read
> this interval.
> 
> Best Regards,
> 
> Ken
> 
> 
> 
> 
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-- 
Albert Chu
address@hidden
Computer Scientist
High Performance Systems Division
Lawrence Livermore National Laboratory