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Understanding PMP metrics

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  • Understanding PMP metrics

    Hi,

    I recently installed PMP 1.1 to monitor an Apache 2 server (cacti), and I've got everything running just fine, but I need some help interpreting the graphs.

    The 'Apache CPU Load' graph shows values on the Y axis with a "m" suffix (100m, 120m, 140m, etc), but I don't understand what that means. Is that a mean percentage over a period of time? I checked the plugin data source values and it looks like it uses an RRD "GAUGE" data source type with a 300 step, but I have no idea what that really means. The values on the graph don't seem to correlate to the Apache web-hosted /server-stats values.

    The "Apache Requests" value also doesn't make sense to me... do these values represent average concurrent requests per time period?

    The "Apache Scoreboard" is the most descriptive graph, but again some of the values (reading request, closing connection, etc) have "m" suffixes and I'm lost on what that means.

    To go a step further, it would be helpful if there was something that made it clear what sort of thresholds a value should / shouldn't have, in terms of best practices / performance. That way we can leverage other Cacti plugins like "thold" to respond to these PMP graphs if certain conditions are met.

    Thanks in advance.

    Ashwini

  • #2
    About m:
    10^-18 a - atto
    10^-15 f - femto
    10^-12 p - pico
    10^-9 n - nano
    10^-6 u - micro
    10^-3 m - milli
    0 (no unit)
    10^3 k - kilo
    10^6 M - mega
    10^9 G - giga
    10^12 T - tera
    10^15 P - peta

    Can you please attach some sample graph and post the corresponding /server-stats data?

    Comment


    • #3
      Hi weber,

      I've attached my CPU Load graph which shows current value of 23.2m. At that time my Apache /server-status showed CPU as:

      CPU Usage: u93.73 s13.02 cu0 cs0 - .0217% CPU load

      If PMP means my CPU Load is 23.2 milliseconds then I guess we're talking mean CPU time for Apache processes, which != load in my understanding or in Apache's server-status. What am I misunderstanding here?



      Comment


      • #4
        It would be awesome if we knew what a good/average/bad CPU Load was in terms of the metrics displayed by the Apache monitoring plugin. That's why I like values in percentages. Milliseconds of CPU time is difficult to interpret when checking the overall CPU load of a service.

        Comment


        • #5
          The graph recflects the correct value in your case and it's not milliseconds, it is what reported by Apache server status, i.e. %

          > CPU Usage: u93.73 s13.02 cu0 cs0 - .0217% CPU load
          This means that .0217% is equal to 21.7m % in your case.


          So "m" is just 10^-3.

          Another example:

          wget -O - http://localhost/apache-status?auto
          Total Accesses: 7064460
          Total kBytes: 7962288
          CPULoad: .132226
          Uptime: 454177
          ReqPerSec: 15.5544
          BytesPerSec: 17952
          BytesPerReq: 1154.14
          BusyWorkers: 1
          IdleWorkers: 10
          Scoreboard: W__________....................................... .................................................. .................................................. .................................................. .................................................. ......

          CPU load of .132226 will be displayed on the graph as 132.23m in the unit reported by the server status. If it's % than %.

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