Re: pcp grafana and graphite - How to convert pcp metric values into percent

[Amer Ather <aather@xxxxxxxxxxx>]

Frank and Nathan,

So what I understand that rate conversion does not work for PMWEBAPI client but works fine for pmval and pmwebd graphite extension.Â

I tested it and that is exactly what I am seeing. pmval is doing rate conversion, but curl is returning raw values. That means our UI client has to do rate conversion when using PMWEBAPI call.

$cat pctavg

kernel.pct.cpu.user = 100 * kernel.all.cpu.user / hinv.ncpuÂ

kernel.pct.cpu.sys Â= 100 * kernel.all.cpu.sys / hinv.ncpuÂ

kernel.pct.cpu.idle = 100 * kernel.all.cpu.idle / hinv.ncpuÂ

kernel.pct.cpu.nice = 100 * kernel.all.cpu.nice / hinv.ncpuÂ

kernel.pct.cpu.intr = 100 * kernel.all.cpu.intr / hinv.ncpuÂ

kernel.pct.cpu.wait.total = 100 * kernel.all.cpu.wait.total / hinv.ncpu

PCP_DERIVED_CONFIG=pctavg pmval -f3 -s3 kernel.pct.cpu.user

metric: Â Âkernel.pct.cpu.user

host: Â Â Âkvick-trustyhvm-i-1e814740

semantics: cumulative counter (converting to rate)

units: Â Â millisec (converting to time utilization)

samples: Â 3

interval: Â1.00 sec

       Â40.487

       Â42.235Â

curl.sh:

--------

CONTEXT=`curl -s -S "http://ec2-204-236-180-248.us-west-1.compute.amazonaws.com:7002/pmapi/context?local=ANYTHING"|awk '{print $3}'`

echo "New Context received from server: $CONTEXT"

curl -s -S "http://ec2-204-236-180-248.us-west-1.compute.amazonaws.com:7002/pmapi/$CONTEXT/_fetch?names=kernel.pct.cpu.idle,kernel.pct.cpu.sys,kernel.pct.cpu.user"

# ./curl.sh

New Context received from server: 253643307

{ "timestamp": { "s":1404323698, "us":955081 },

"values": [

{ "pmid":2143289350, "name":"kernel.pct.cpu.idle","instances": [

{"value":1.92329e+11}] },

{ "pmid":2143289349, "name":"kernel.pct.cpu.sys","instances": [

{"value":1.53737e+10}] },

{ "pmid":2143289348, "name":"kernel.pct.cpu.user","instances": [

{"value":1.51585e+10}] }] }

Amer.

On Tue, Jul 1, 2014 at 8:33 PM, Frank Ch. Eigler <fche@xxxxxxxxxx> wrote:

Amer Ather <aather@xxxxxxxxxxx> writes:

> [...] Âgrafana/graphite reports these values from archives correctly
> in percent. ÂHowever, pmapi fetch returns wrong values: [...]

The graphite emulation code in pmwebd performs rate conversion (since
it has easy historical data to go from); the PMWEBAPI part passes raw
metric values (and libpcp doesn't want to rate-convert [1]). ÂThis
could explain the mismatch between your expectations and what you're
seeing.

[1] http://oss.sgi.com/archives/pcp/2014-05/msg00104.html

- FChE

--

Thanks,

Amer Ather

Cloud Performance Engineering

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