A 1 second interval on the firmware level is fairly heavy use.  You will not 
want that.  Anything less than about 2 minutes is a bit overkill for a small 
embedded system that shares its resources.

For what it does, IPMITool is probably the fastest In-band and OOB IPMI level 
tool you will find.  Most of what takes so long is establishing communication 
with the management controller.  There really is not much that can improve this 
as it is a limitation by the management controller.

RE: power monitoring every second.  Of course you'll see fluctuations; you are 
influencing that by making the MC work hard to poll the sensor, queue the data, 
send it though the communication interface, etc...  Long ago I tested systems 
like that and soon realized that the sampling caused a 40 - 60 watt increase in 
power usage (or error) versus sampling over a longer period of time.  I 
compared the results with an external watt hour meter.  There wasn't much of a 
difference between the longer sample period average and the real watt hour 
meter.

RE: daemon.  There is a bit of a security problem here.  You might want to read 
the IPMI spec. before taking this path.

My moot points anyway.  ;)

- Eric



-----Original Message-----
From: Mark Seger [mailto:mark.se...@hp.com] 
Sent: Friday, January 16, 2009 4:49 AM
To: Carol Hebert
Cc: ipmitool-devel@lists.sourceforge.net
Subject: Re: [Ipmitool-devel] Happy New Year, Happy New ipmitool

Carol Hebert wrote:
> Hi and Happy '09!
>
> To celebrate the New Year, I propose we start working on rolling
> ipmitool to v1.8.11 to include all the great fixes and patches folks
> have been sending in since last summer!  Do you have a fix you've been
> using in your local ipmitool version?  Send it in for review!  Do you
> have a patch or an idea for some new functionality or support you'd like
> to see get into the tool?  Send it in for review! 
Well you did ask, so here ya go...

I'm the author of collectl [see: http://collectl.sourceforge.net/], 
which is a tool for doing system monitoring.  A couple of the things I 
think that sets it apart from others is it's very light-weight and that 
it collects a very broad set of data, making it possible to drill down 
and see what the state of all your system resources are any point in time.

About 6 months ago I discovered ipmitool and now use it to monitor 
temps, fans and power though I could see adding other resources as 
well.  My own problem with ipmitool is that while it's pretty 
light-weight, it's not light-weight enough and so I had to give it its 
own monitoring interval - I monitor most things every 10 seconds when 
running as a daemon, though there are those who sample every 5 seconds 
or even 1.  I did some tests with ipmitool running at those frequencies 
and there was just too much system load compared to collectl proper 
which uses <0.1% and so I'm only sampling sensors every 2 minutes, which 
I thought at first was reasonable.

However since adding power sensor monitoring and watching the power 
every second, just to see what's happening over short bursts of time, I 
saw that sensor changes much more frequently than I thought it would.  
Given all the interest in green computing I can see where more frequent 
power monitoring would be a good thing.  I even went as far to see what 
it might take to query ipmi directly to save the overhead of running a 
new instance of ipmitool every sample period but I think I can now 
appreciate just how complex ipmi is and would prefer to continue to use 
ipmitool as it already does a great job.

So, as for an enhancement I'd like to see a way to run it at rates on 
the order of a few seconds and not incur a lot of overhead.  I'm basing 
this on my assumption that the bulk of ipmitool's time is spent on 
starting the image as well as establishing the internal communications 
connection(s).   If so, my logical conclusion would be there needs to be 
a way to do the initialization one time and not exit.  While I can think 
of a few ways to do it, and I think the first is probably the easiest, 
perhaps someone intimately familiar with ipmitool's innards such as 
yourself would have better ways:
- run it as a daemon, allowing it to receive commands over a socket and 
send the results back
- build some sort of library that could be called via something like 
perl, once call to initialize and a second to query, probably others...

In any event, if it turns out that sending/receiving the command to the 
sensors is where all the is spent and startup is less of a big deal, 
this whole discussion is moot.

Anyhow, you DID ask...  ;-)
-mark


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