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

[Arnon Warshavsky <arnon@qwilt.com>]

I

On Fri, Jun 3, 2016 at 10:23 PM, Wiles, Keith <keith.wiles@intel.com> wrote:

>
> On 6/3/16, 2:18 PM, "Neil Horman" <nhorman@tuxdriver.com> wrote:
>
> >On Fri, Jun 03, 2016 at 07:07:50PM +0000, Wiles, Keith wrote:
> >> 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:
> >> >
> >> >
> >> >
> >> >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:
> >> >>
> >> >> >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.
> >> >>
> >> >> I hope that clears that up, but let me know.
> >> >>
> >> >yes, that clarifies your thinking, and I agree with it.  Thank you!
> >> >Neil
> >> >
> >> >> ++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
> >> >> >>
> >> >> >>
> >> >> >>
> >> >> >
> >> >>
> >> >>
> >> >>
> >> >
> >> >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)
> >> >
> >> >
> >> >
> >> >
> >> >/Arnon
> >> >
> >> >Arnon,
> >> >
> >> >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?
> >>
> >
> >I'm not opposed to default values, but it seems to me that if we are
> splitting
> >out a configuration storage library from dpdk, part of the initzliation
> of that
> >library can be installing default values.  That is to say, instead of
> having the
> >code specific areas assume a default value if none is present in the
> config, an
> >init function for the configuration storage library would just populate
> the
> >keystore.  That way all the dpdk itself has to do is a key lookup.
>
> +1
>
> If someone needs or wants default values in the API call then a wrapper
> functions around the basic keystore APIs can be done by the developer or we
> can add a new set of APIs to provide that type of feature, just like the
> variable type APIs. Just as long as the basic APIs do not exclude we can
> add it later.
>
> >
> >Neil
> >
> >> >
> >> >Does that make sense?
> >> >
> >> >++Keith
> >> >
> >>
> >>
> >>
> >
>
>
>
>
Yes.
I like to use the the getValue(myAlternativeDefault) concept when I have
different granularity defaults coming from different hierarchies,
but per dpdk as a single configuration separation to an init phase indeed
makes more sense, so +1 here too