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Re: A few questions

To: Alan Bailey <abailey@xxxxxxxxxxxxx>
Subject: Re: A few questions
From: kenmcd@xxxxxxxxxxxxxxxxx
Date: Sun, 4 Feb 2001 09:56:03 +1100 (EST)
Cc: pcp@xxxxxxxxxxx
In-reply-to: <Pine.LNX.4.10.10101101421420.28431-100000@xxxxxxxxxxxxxxxxxxx>
Reply-to: kenmcd@xxxxxxxxxxxxxxxxx
Sender: owner-pcp@xxxxxxxxxxx
Max responded to this, I'm justing adding a few additional snippets.

On Wed, 10 Jan 2001, Alan Bailey wrote:

> A few simple questions...
> 
> - I'm using the following command:
> 
> > pmafm Latest pmdumplog -S "@whatever"
> 
> This is all fine and good.  But say I just want a single metric.  This
> doesn't work:
> 
> > pmafm Latest pmdumplog -S "@whatever" mem.freemem
> pmdumplog: Cannot open archive "mem.freemem": No such file or directory
> 
> Obviously, this is because there is no archive on the command line, and
> mem.freemem is thought to be the archive.  Is there a way around this, or
> is this just the way it is?

1. use pmafm list to get the NAME of the archive from the Latest folio

    kenj-pc 66% pmafm Latest list
            
    PCP Archive Folio: Latest
    Created: on kenj-pc at Sat Feb  3 09:30:13 EST 2001
    Creator: mkaf

    Ordinal Hostname             Archive Basename
      [  1] kenj-pc              20010203.09.30

2. if the pmlogger is still running use pmlc to connect to pmlogger
   and flush the output buffers

    kenj-pc 67% pmlc 
    Performance Co-Pilot Logger Control (pmlc), Version 2.1.9

    pmlc commands

      show loggers [@<host>]             display <pid>s of running pmloggers
      connect _logger_id [@<host>]       connect to designated pmlogger
      status                             information about connected pmlogger
      query metric-list                  show logging state of metrics
      new volume                         start a new log volume
      flush                              flush the log buffers to disk

      log { mandatory | advisory } on <interval> _metric-list
      log { mandatory | advisory } off _metric-list
      log mandatory maybe _metric-list

      timezone local|logger|'<timezone>' change reporting timezone
      help                               print this help message
      quit                               exit from pmlc

      _logger_id   is  primary | <pid> | port <n>
      _metric-list is  _metric-spec | { _metric-spec ... }
      _metric-spec is  <metric-name> | <metric-name> [ <instance> ... ]

    pmlc> connect primary
    pmlc> flush
    pmlc> quit
    Goodbye

3. Check the archive label.

    kenj-pc 68% pmdumplog -L 20010203.09.30
    Log Label (Log Format Version 2)
    Performance metrics from host kenj-pc
      commencing Sat Feb  3 09:30:02.076 2001
      ending     Sat Feb  3 16:35:30.253 2001
    Archive timezone: EST-11
    PID for pmlogger: 1084

4. Use -S with pmdumplog + archive name + metric

    kenj-pc 69% pmdumplog -S "@14:00" 20010203.09.30 kernel.all.load

    16:35:30.170  60.2.0 (kernel.all.load):  inst [1 or "1 minute"] value 
0.050000001

    16:35:30.253  60.2.0 (kernel.all.load):  inst [1 or "1 minute"] value 
0.05000000

But as Max suggested pmdumplog may not be the weapon of choice here
... pmval or even pmie -v may be better.

> - When I run pmlogger_check to start up the pmlogger processes, there is a
> considerable gap between each one starting up.  Is this on purpose so that
> the pmlogger processes are staggered and don't eat up the machine at the
> same time?  Or is there some other reason...

pmlogger_check starts the pmlogger and then waits until it can connect
to the pmlogger with pmlc ... and the pmlogger needs to read the config
file, contact pmcd, exchange messages about metadata, and generally
muck about ... pmlogger_check is waiting so that it can reliably report
any failures when each pmlogger is started.

Running pmlogger_check with sh -x may give you an idea if this hypothesis
is correct.

> - Is there a way to round the time values in the archives to, say, every
> five minutes, so that 13:42:23.045 would become 13:40?  I doubt this,
> because I know the code for any arbitrary rounding time would be
> nontrivial, and this isn't that necessary.

Yep.  From man 1 PCPIntro ...

   -A align
          By  default  samples are not necessarily aligned on
          any natural unit of time.  The  -A  option  may  be
          used  to  force the initial sample to be aligned on
          the boundary of a natural time unit.   For  example
          -A 1sec, -A 30min and -A 1hour specify alignment on
          whole seconds, half and whole hours respectively.

          The align argument follows the syntax for an inter­
          val argument described above for the -t option.

          Note that alignment occurs by advancing the time as
          required, and that -A acts as a modifier to advance
          both  the  start  of  the time window (see the next
          section) and the origin time (if the -O  option  is
          specified).


> - Is pminfo the suggested way to get a single value from an archive at a
> certain time, and pmdumplog the suggested way to get a range of time
> values?

You need -S for this and pminfo does not grok that option.  Also
if the metric is a counter, pminfo will _not_ rate convert it.

I would tend to use pmie for both cases ... varying the -T will
control how many values are reported.



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