On Thu, 6 Dec 2007, Brad Nicholes wrote:
> >>> On Wed, Dec 5, 2007 at 3:48 PM, in message
> <[EMAIL PROTECTED]>, Matthias
> Blankenhaus <[EMAIL PROTECTED]> wrote:
> > Hi Brad !
> >
> > Nice meeting you yesterday :-)
> >
> > I took a closer look at PCP to see what it uses for the meta level
> > description for every metric. I thought this might be interesting for
> > you. Here you go:
> >
> >
> > - Data type: union of all C types, plus blob
> > - Semantics: counter, instant, descrete
> > - Units and scale: dimension and scale for space, time, count
> >
> >
> > Here are some examples:
> >
> >
> > kernel.all.load [1, 5 and 15 minute load average]
> > Data Type: float InDom: 60.2 0xf000002
> > Semantics: instant Units: none
> >
> > kernel.percpu.cpu.user [percpu user CPU time metric from /proc/stat]
> > Data Type: 64-bit unsigned int InDom: 60.0 0xf000000
> > Semantics: counter Units: millisec
> >
> >
> > For detailed info you can check out "man PMAPI" on any SLES box.
> >
> >
> > Matthias
>
> If I am understanding this correctly, this is actually similar in concept to
> the XDR restructuring that I did for gmond. However the metadata and the
> value message are split into two different structures. The metadata is a
> struct that contains the basic metric description elements plus a blob
> (basically. It is really an array of additional elements). The value message
> is a union of all of the supported data types. Both message types (metadata,
> value) carry a metric ID header struct that defines the host, metric name and
> spoof indicator. Since this structure is basically the header for every XDR
> message, even before the XDR message type is determined, the host and metric
> can be identified. Take a look at lib/protocol.h.
Among other thinks I saw this:
enum Ganglia_value_types {
GANGLIA_VALUE_UNKNOWN = 0,
GANGLIA_VALUE_STRING = 1,
GANGLIA_VALUE_UNSIGNED_SHORT = 2,
GANGLIA_VALUE_SHORT = 3,
GANGLIA_VALUE_UNSIGNED_INT = 4,
GANGLIA_VALUE_INT = 5,
GANGLIA_VALUE_FLOAT = 6,
GANGLIA_VALUE_DOUBLE = 7,
};
What does int, short amount to for various platforms ? I think to
make this portable you might want to make it explicit to avoid any
integral promotion problem, e.g. have INT32, UINT32, INT64, UINT64 types.
But maybe, I misunderstood the concept.
>
> You asked about spoofing or IP proxying the other night. Creating a proxied
> metric metadata or value message is really no different than any other metric
> message. The difference is in the additional metadata that is added to the
> message. The following API will convert a regular metric message to a
> proxied message:
>
> Ganglia_metadata_add (ganglia_metric, SPOOF_HOST, host_name);
>
> Basically all this is doing is adding a proxied host name or IP as extra
> metadata to a metric message (metadata or value). Gmond looks at the
> SPOOF_HOST and alters the XDR packet with the appropriate host name. This is
> actually how gmetric now deals with actual metrics vs. spoofed metrics.
>
Thanx, this should work.
Matthias
> Brad
>
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