Re: [dpdk-dev] Question about telemetry on 18.11 release

[Hideyuki Yamashita <yamashita.hideyuki@po.ntt-tx.co.jp>]

Hi Ferruh, Rami

Thanks for your answering me at this busy time during 
release of 18.11.

I will wait response from your colleague.
>Ferruh 

Rami, thanks for your advice.
If I understand you correctly, then 
there already exist APIs to collect statistic 
information inside dpdk including CPU usage.

I've read the l2fwd-jobstats code in addition to documents 
you pointed out and found that there exists code sample showing
statistics per lcore. (You are right)

So my next questions are 

Q5.Are there any API document for jobstats?
I've already read header file definition.
I've already read sample coce.
But API documenation will be a great help to 
understand semantics(or usage) of each APIs 
within jobstats.

Q6. Is it possible to use those (jobstats and telemetry) together?

If I understand l2fwd-jobstats sample code correctly,
statistic information is periodicaly stored into memory
(variables), so at that timing application can pass 
statistics information to teremetry API (server side).
But that is only my guess.

Q7.Are there any samples implementing above?
(My guess is 'no'. jobstats sample only use 'jobstats'
and 'telemetry' sample only use 'telemetry' though.)

Have a nice day and thanks again.
BR,
Hideyuki Yamashita
NTT TechnoCross

> Hi Hideyuki,
> 
> Regarding your questions about DPDK CPU usage, etc:
> I believe that due to the way PMDs are implemented, maybe one
> should consider using DPDK RTE jobstats API for collecting stats for a DPDK
> app. This API reflects better the actual DPDK app stats.
> See an example in:
> https://doc.dpdk.org/guides/sample_app_ug/l2_forward_job_stats.html
> And also see:
> https://doc.dpdk.org/api/rte__jobstats_8h_source.html
> 
> Regards,
> Rami Rosen
> 
> ?????? ??? ??, 21 ????? 2018, 09:50, ??? Hideyuki Yamashita <
> yamashita.hideyuki@po.ntt-tx.co.jp>:
> 
> > Hello,
> >
> > I have some basic questions about telemetry API
> > which is planned to be relaesed in 18.11.
> >
> > Note that I have read the follwoing document.
> > https://doc.dpdk.org/guides/howto/telemetry.html
> >
> > Q1. In general dpdk application use polling when
> > receiving packets. So CPU usage is always looks 100%
> > when measured using e.g. vmstat even if there is no packet receiving.
> > (CPU is busy for polling packets)
> > Is that correct?
> >
> > Q2. Is it correct understanding that dpdk application
> > can send "any" value(or metric) to client if client
> > requested via "telemetry" framework?
> >
> > Q3.Is it possible to query "real cpu usage" from dpdk
> > application using "telemetry" framework?
> > ("real cpu usage" I mean if 0 pakcket incoming,
> > cpu usage indicates almost 0 %)
> >
> > Q4. Is it possible to inform client about fault or some
> > trouble from dpdk application?
> >
> > Background  I ask above is that
> > - I am relative new to DPDK world and have almost no knowledge about
> > "telemetry"
> > - I am interested in how dpdk applications can "scales" on platform
> > like OpenStack. I think some mesurement mechanism required
> > and I thought it might be "telemetry" APIs.
> >
> > Thanks in advance.
> >
> > BR,
> > Hideyuki Yamashita
> > NTT TechnoCross
> >
> >
> >