Re: high frequency metrics collection and trace

[fche@xxxxxxxxxx (Frank Ch. Eigler)]

Hi, Ken -


kenj wrote:

> [...]
>> Does the PMAPI have to use fetch/pull to collect data with certain
>> fixed frequency? I assume that PMCD cannot push data to the monitoring
>> side via PMAPI. 
>
> There is very little client state maintained at pmcd, so clients are
> free to fetch at whatever frequency they desire and indeed pmlogger and
> pmie collect different groups of metrics at different frequencies.
>
> Pushing from pmcd is nver going to happen (this is not an SNMP trap
> model!).

Might it make sense to add a repeated-pmFetch type of operation to the
wire protocol at some point?  Imagine if the latency/throughput
overhead of requesting the same data metrics over and over again
becomes noticeable?  (From a brief tcpdump experiment, pmval request
traffic is almost as large as pmcd response.)

- FChE