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

["Wiles, Keith" <keith.wiles@intel.com>]

On 6/3/16, 2:00 PM, "dev on behalf of Wiles, Keith" <dev-bounces@dpdk.org on behalf of keith.wiles@intel.com> wrote:

>On 6/3/16, 1:52 PM, "Arnon Warshavsky" <arnon@qwilt.com<mailto:arnon@qwilt.com>> wrote:
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>On Fri, Jun 3, 2016 at 9:38 PM, Neil Horman <nhorman@tuxdriver.com<mailto:nhorman@tuxdriver.com>> wrote:
>On Fri, Jun 03, 2016 at 06:29:13PM +0000, Wiles, Keith wrote:
>>
>> On 6/3/16, 12:44 PM, "Neil Horman" <nhorman@tuxdriver.com<mailto:nhorman@tuxdriver.com>> wrote:
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>> >On Fri, Jun 03, 2016 at 04:04:14PM +0000, Wiles, Keith wrote:
>> >> Sorry, I deleted all of the text as it was getting a bit long.
>> >>
>> >> Here are my thoughts as of now, which is a combination of many suggestions I read from everyone’s emails. I hope this is not too hard to understand.
>> >>
>> >> - Break out the current command line options out of the DPDK common code and move into a new lib.
>> >>   - At this point I was thinking of keeping the rte_eal_init(args, argv) API and just have it pass the args/argv to the new lib to create the data storage.
>> >>      - Maybe move the rte_eal_init() API to the new lib or keep it in the common eal code. Do not want to go hog wild.
>> >>   - The rte_eal_init(args, argv) would then call to the new API rte_eal_initialize(void), which in turn queries the data storage. (still thinking here)
>> >These three items seem to be the exact opposite of my suggestion.  The point of
>> >this change was to segregate the parsing of configuration away from the
>> >initalization dpdk using that configurtion.  By keeping rte_eal_init in such a
>> >way that the command line is directly passed into it, you've not changed that
>> >implicit binding to command line options.
>>
>> Neil,
>>
>> You maybe reading the above wrong or I wrote it wrong, which is a high possibility. I want to move the command line parsing out of DPDK an into a library, but I still believe I need to provide some backward compatibility for ABI and to reduce the learning curve. The current applications can still call the rte_eal_init(), which then calls the new lib parser for dpdk command line options and then calls rte_eal_initialize() or move to the new API rte_eal_initialize() preceded by a new library call to parse the old command line args. At some point we can deprecate the rte_eal_init() if we think it is reasonable.
>>
>> >
>> >I can understand if you want to keep rte_eal_init as is for ABI purposes, but
>> >then you should create an rte_eal_init2(foo), where foo is some handle to in
>> >memory parsed configuration, so that applications can preform that separation.
>>
>> I think you describe what I had planned here. The rte_eal_initialize() routine is the new rte_eal_init2() API and the rte_eal_init() was only for backward compatibility was my thinking. I figured the argument to rte_eal_initialize() would be something to be decided, but it will mostly likely be some type of pointer to the storage.
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>> I hope that clears that up, but let me know.
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>yes, that clarifies your thinking, and I agree with it.  Thank you!
>Neil
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>> ++Keith
>>
>> >
>> >Neil
>> >
>> >>   - The example apps args needs to be passed to the examples as is for now, then we can convert them one at a time if needed.
>> >>
>> >> - I would like to keep the storage of the data separate from the file parser as they can use the ‘set’ routines to build the data storage up.
>> >>   - Keeping them split allows for new parsers to be created, while keeping the data storage from changing.
>> >> - The rte_cfg code could be modified to use the new configuration if someone wants to take on that task ☺
>> >>
>> >> - Next is the data storage and how we can access the data in a clean simple way.
>> >> - I want to have some simple level of hierarchy in the data.
>> >>   - Having a string containing at least two levels “primary:secondary”.
>> >>      - Primary string is something like “EAL” or “Pktgen” or “testpmd” to divide the data storage into logical major groups.
>> >>         - The primary allows us to have groups and then we can have common secondary strings in different groups if needed.
>> >>      - Secondary string can be whatever the developer of that group would like e.g. simple “EAL:foobar”, two levels “testpmd:foo.bar”
>> >>
>> >>   - The secondary string is treated as a single string if it has a hierarchy or not, but referencing a single value in the data storage.
>> >>      - Key value pairs (KVP) or a hashmap data store.
>> >>         - The key here is the whole string “EAL:foobar” not just “foobar” secondary string.
>> >>            - If we want to have the two split I am ok with that as well meaning the API would be:
>> >>              rte_map_get(mapObj, “EAL”, “foo.bar”);
>> >>              rte_map_set(mapObj, “EAL”, “foo.bar”, value);
>> >>            - Have the primary as a different section in the data store, would allow for dumping that section maybe easier, not sure.
>> >>               - I am leaning toward
>> >>      - Not going to try splitting up the string or parse it as it is up to the developer to make it unique in the data store.
>> >> - Use a code design to make the strings simple to use without having typos be a problem.
>> >>    - Not sure what the design is yet, but I do not want to have to concat two string or split strings in the code.
>> >>
>> >> This is as far as I have gotten and got tired of typing ☺
>> >>
>> >> I hope this will satisfy most everyone’s needs for now.
>> >>
>> >>
>> >> Regards,
>> >> Keith
>> >>
>> >>
>> >>
>> >
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>Keith
>What about the data types of the values?
>I would assume that as a library it can provide the service of typed get/set and not leave conversion and validation to the app.
>
>rte_map_get_int(map,section,key)
>rte_map_get_double(...)
>rte_map_get_string(...)
>rte_map_get_bytes(...,destBuff , destBuffSize) //e.g byte array of RSS key
>This may also allow some basic validity of the configuration file
>Another point I forgot about is default values.
>We sometimes use a notation where the app also specifies a default value in case the configuration did not specify it
>  rte_map_get_int(map,section,key , defaultValue )
>and specify if this was a mandatory that has no default
>  rte_map_get_int_crash_if_missing (map,section,key)
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>/Arnon
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>Arnon,
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>Yes, I too was thinking about access type APIs, but had not come to a full conclusion yet. As long as the API for get/put can return any value, we can add a layer on top of these primary get/put APIs to do some basic type checking. This way the developer can add his/her own type checking APIs or we provide a couple basic types for simple values.

One more thing. I had not thought about default values as the defaults are handle directly by the code when an option is not applied. I think it should be left up to the developer to add default values to the storage or handle it when an option is not found in the storage.

If I understand your code above the API would pass in a default value if one did not exist in the storage, which I guess is reasonable. Anyone think this is a good idea or not?

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>Does that make sense?
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>++Keith
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