[dpdk-dev] [RFC] Yet another option for DPDK options

[Wiles, Keith]

On 6/1/16, 11:18 AM, "Richardson, Bruce" <bruce.richardson at intel.com> wrote:

>On Wed, Jun 01, 2016 at 10:58:41AM -0500, Jay Rolette wrote:
>> On Wed, Jun 1, 2016 at 10:00 AM, Wiles, Keith <keith.wiles at intel.com> wrote:
>> 
>> > Started from the link below, but did not want to highjack the thread.
>> > http://dpdk.org/ml/archives/dev/2016-June/040021.html
>> >
>> > I was thinking about this problem from a user perspective and command line
>> > options are very difficult to manage specifically when you have a large
>> > number of options as we have in dpdk. I see all of these options as a type
>> > of database of information for the DPDK and the application, because the
>> > application command line options are also getting very complex as well.
>> >
>> > I have been looking at a number of different options here and the
>> > direction I was thinking was using a file for the options and
>> > configurations with the data in a clean format. It could have been a INI
>> > file or JSON or XML, but they all seem to have some problems I do not like.
>> > The INI file is too flat and I wanted a hierarchy in the data, the JSON
>> > data is similar and XML is just hard to read. I wanted to be able to manage
>> > multiple applications and possible system the DPDK/app runs. The problem
>> > with the above formats is they are just data and not easy to make decisions
>> > about the system and applications at runtime.
>> >
>> 
>> INI format is simplest for users to read, but if you really need hierarchy,
>> JSON will do that just fine. Not sure what you mean by "JSON data is
>> similar"...
>> 
>> 
>I'd be quite concerned if we start needing lots of hierarchies for configuration.
>
>I'd really just like to see ini file format used for this because:
>* it's a well understood, simple format
>* very easily human readable and editable
>* lots of support for it in lots of languages
>* hierarchies are possible in it too - just not as easy as in other formats
>  though. [In a previous life I worked with ini files which had address
>  hierarchies 6-levels deep in them. It wasn't hard to work with]

Maybe INI will work for hierarchies, but I bet it was not super obvious without a lot of comments.

>* it works well with grep since you must have one value per-line
>* it allows comments

We can have comments in any format not really a deciding factor IMHO.

>* we already have a DPDK library for parsing them
>
>However, for me the biggest advantage of using something like ini is that it
>would force us to keep things simple!

Simple is good and with any of these formats you can be simple or complex, just depends on the usage.

If all I wanted was to run a few examples then I would say INI is just fine. I would like to have a configuration file that can help me understand the system and pick the right options for a two socket system or one socket or system with 4 cores or 16 or running in a VM/container or not or FreeBSD or Linux or … you get the picture all with a single image (maybe not with the FreeBSD/Linux).

In a static data format you do not get these easily (maybe if you added a bunch of different options and then made the code figure out which ones to use), in a interpreted language you do get them for free.

This is why I do not want just a database of options.

>
>I'd stay away from formats like json or XML that are designed for serializing
>entire objects or structures, and look for something that allows us to just
>specify configuration values.
>
>Regards,
>/Bruce
>
>