Re: [dpdk-dev] [PATCH v3] pipeline: add statistics for librte_pipeline

["Ramia, Kannan Babu" <kannan.babu.ramia@intel.com>]

The confusion is due to whether you consider stats as a library feature or Debug feature. Mostly log levels are considered as debug features in the production system and controlled system wide flag not per library flags. While statistics could be considered as a library feature which could be turned on and off depends on the application needs.  I am with Cristian to have per library feature configuration flag for statistics. 

Regards
Kannan Babu

-----Original Message-----
From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Dumitrescu, Cristian
Sent: Friday, May 29, 2015 12:56 AM
To: Rajagopalan Sivaramakrishnan; dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v3] pipeline: add statistics for librte_pipeline

Hi Raja,

Thanks for your input.

I think we have the following options identified so far for stats collection configuration:

1. Stats configuration through the RTE_LOG_LEVEL 2. Single configuration flag global for all DPDK libraries 3. Single configuration flag per DPDK library

It would be good if Thomas and Stephen, as well as others, would reply with their preference order.

My personal preference order is: 3., 2., 1., but I can work with any of the above that is identified by the majority of the replies. My goal right now is reaching a conclusion on this item as soon as we can.

Regards,
Cristian



> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Rajagopalan 
> Sivaramakrishnan
> Sent: Wednesday, May 27, 2015 11:45 PM
> To: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v3] pipeline: add statistics for 
> librte_pipeline
> 
> 
> > > You also reiterate that you would like to have the stats always enabled.
> You
> > can definitely do this, it is one of the available choices, but why 
> > not also accommodate the users that want to pick the opposite 
> > choice? Why force apps to spend cycles on stats if the app either 
> > does not want these
> counters
> > (library counters not relevant for that app, maybe the app is only
> interested
> > in maintaining some other stats that it implements itself) or do not 
> > want them anymore (maybe they only needed them during debug phase), etc?
> > Jay asked this question, and I did my best in my reply to describe 
> > our motivation (http://www.dpdk.org/ml/archives/dev/2015-
> May/017992.html).
> > Maybe you missed that post, it would be good to get your reply on 
> > this one too.
> >
> > I want to see DPDK get out of the config madness.
> > This is real code, not an Intel benchmark special.
> 
> 
> I agree that statistics will definitely be required in most real-world 
> production environments and the overhead from per-core stats gathering 
> will be minimal if the data structures are such that CPU cache 
> thrashing is avoided.
> However, if there are scenarios where it is desirable to turn stats 
> off, I think we can live with a config option.
> I am not comfortable with using the log level to enable/disable 
> statistics as they are not really related. A separate config option 
> for stats collection seems like a reasonable compromise.
> 
> Raja