Hi Harry, > > > > Thanks everybody for the input on the RFC - appreciated! From an > > application point-of-view, I > > see merit in Konstantin's suggestions for the API, over the RFC I sent > > previously. I will re- > > work the API taking inspiration from both APIs and send an RFCv2, you'll be > > on CC :) > > > Hi All, > > This email is the v2 RFC for Service Cores, in response to the v1 sent > previously[1]. > The service-cores API has been updated, and various concepts have changed. > > The API has been redesigned, with Konstantin's API suggestions as a base, and > the > other comments taken into account. In my opinion this v2 API is more > application-centric, > and enables the common application tasks much better. Such tasks are for > example start/stop > of a service, and add/remove of a service core. > > In particular this version of the API enables applications that are not aware > of services to > benefit from the services concept, as EAL args can be used to setup services > and service cores. > With this design, switching to/from SW/HW PMD is transparent to the > application. An example > use-case is the Eventdev HW PMD to Eventdev SW PMD that requires a service > core. > > I have noted the implementation comments that were raised on the v1. For v2, > I think our time > is better spent looking at the API design, and I will handle implementation > feedback in the > follow-up patchset to v2 RFC. > > Below a summary of what we are trying to achieve, and the current API design. > Have a good weekend! Cheers, -Harry
Looks good to me in general. The only comment I have - do we really need to put it into rte_eal_init() and a new EAL command-line parameter for it? Might be better to leave it to the particular app to decide. Konstantin > > > Summary of goals (summarized from a previous email) > 1. Allowing libraries and drivers to register the fact that they require > background processing > 2. Providing support for easily multiplexing these independent functions from > different libs onto a different core > 3. Providing support for the application to configure the running of these > background services on specific cores > 4. Once configured, hiding these services and the cores they run on from the > rest of the application, > so that the rest of the app logic does not need to change depending on > whether service cores are in use or not > > > === RFC v2 API === > > There are 3 parts to the API; they separate the concerns of each "user" of > the API: > - Service Registration > - Service Config > - ServiceCore Config > > Service Registration: > A service requires a core. It only knows about its NUMA node, and that it > requires CPU time. > Registration of a service requires only that information. > > Service Config: > An application may configure what service runs where using the Service Config > APIs. > EAL is capable of performing this during rte_eal_init() if requested by > passing a > --service-cores argument. The application (mostly) calls these functions at > initialization > time, with start() and stop() being available to dynamically switch on/off a > service if required. > > ServiceCore Config > An application can start/stop or add/remove service-lcores using the > ServiceCore Config, allowing > dynamically scaling the number of used lcores by services. Lcores used as > service-cores are removed > from the application coremask, and are not available to remote_launch() as > they are already in use. > > > Service Registration: > int32_t rte_service_register(const struct rte_service_spec *spec); > int32_t rte_service_unregister(struct rte_service_spec *service); > > Service Configuration: > uint32_t rte_service_get_count(void); > struct rte_service_spec *rte_service_get_by_id(uint32_t id); > const char *rte_service_get_name(const struct rte_service_spec *service); > int32_t rte_service_set_coremask(struct rte_service_spec *service, const > rte_cpuset_t *coremask); > int32_t rte_service_start(struct rte_service_spec *service); /* runtime > function */ > int32_t rte_service_stop(struct rte_service_spec *service); /* runtime > function */ > > ServiceCore Configuration: > int32_t rte_service_cores_start(void); > int32_t rte_service_cores_stop(void); > int32_t rte_service_cores_add(const rte_cpuset_t *coremask); > int32_t rte_service_cores_del(const rte_cpuset_t *coremask); > > > I am working on a patchset - but for now I would appreciate general design > feedback, > particularly if a specific use-case is not handled.
