On 5/3/2023 8:58 AM, Jerin Jacob wrote: > On Tue, May 2, 2023 at 4:49 PM Ferruh Yigit <[email protected]> wrote: >> >> On 4/25/2023 5:09 AM, Jerin Jacob wrote: >>> On Mon, Apr 24, 2023 at 9:36 PM Ferruh Yigit <[email protected]> wrote: >>>> >>>> On 4/19/2023 11:15 AM, Jerin Jacob wrote: >>>>> On Wed, Apr 19, 2023 at 3:24 PM Sivaprasad Tummala >>>>> <[email protected]> wrote: >>>>>> >>>>>> A new API to allow power monitoring condition on event port to >>>>>> optimize power when no events are arriving on an event port for >>>>>> the worker core to process in an eventdev based pipelined application. >>>>>> >>>>>> Signed-off-by: Sivaprasad Tummala <[email protected]> >>>>>> + * >>>>>> + * @param dev_id >>>>>> + * Eventdev id >>>>>> + * @param port_id >>>>>> + * Eventdev port id >>>>>> + * @param pmc >>>>>> + * The pointer to power-optimized monitoring condition structure. >>>>>> + * >>>>>> + * @return >>>>>> + * - 0: Success. >>>>>> + * -ENOTSUP: Operation not supported. >>>>>> + * -EINVAL: Invalid parameters. >>>>>> + * -ENODEV: Invalid device ID. >>>>>> + */ >>>>>> +__rte_experimental >>>>>> +int >>>>>> +rte_event_port_get_monitor_addr(uint8_t dev_id, uint8_t port_id, >>>>>> + struct rte_power_monitor_cond *pmc); >>>>> >>>>> + eventdev driver maintainers >>>>> >>>>> I think, we don't need to expose this application due to applications >>>>> 1)To make applications to be transparent whether power saving is enabled >>>>> or not? >>>>> 2)Some HW and Arch already supports power managent in driver and in HW >>>>> (Not using CPU architecture directly) >>>>> >>>>> If so, that will be translated to following, >>>>> a) Add rte_event_port_power_saving_ena_dis(uint8_t dev_id, uint8_t >>>>> port_id, bool ena) for controlling power saving in slowpath. >>>>> b) Create reusable PMD private function based on the CPU architecture >>>>> power saving primitive to cover the PMD don't have native power saving >>>>> support. >>>>> c)Update rte_event_dequeue_burst() burst of PMD callback to use (b). >>>>> >>>>> >>>> >>>> Hi Jerin, >>> >>> Hi Ferruh, >>> >>>> >>>> ethdev approach seems applied here. >>> >>> Understands that. But none of the NIC HW supports power management at >>> HW level like eventdev, so that way >>> for what we are doing for ethdev is a correct abstraction for ethdev. >>> >> >> What I understand is there is HW based event manager and SW based ones, >> SW based ones can benefit more from CPU power optimizations, for HW >> event managers if there is not enough benefit they can just ignore the >> feature. >> >>>> >>>> In ethdev, 'rte_event_port_get_monitor_addr()' equivalent is >>>> 'rte_eth_get_monitor_addr()'. >>>> >>>> Although 'rte_eth_get_monitor_addr()' is public API, it is currently >>>> only called from Rx/Tx callback functions implemented in the power library. >>>> But I assume intention to make it public is to enable users to implement >>>> their own callback functions that has custom algorithm for the power >>>> management. >>> >>> If there is a use case for customizing with own callback, we can provide >>> that. >>> Provided NULL is valid with default algorithm. >>> >>>> >>>> And probably same is true for the 'rte_event_port_get_monitor_addr()'. >>>> >>>> >>>> Also instead of implementing power features for withing PMDs, isn't it >>>> better to have a common eventdev layer for it? >>> >>> We can have rte_evetdev_pmd_* APIs as non-public APIs. >>> My only objection is to NOT introduce _monitor_ APIs at eventdev level, >>> Instead, _monitor_ is one way to do it in SW, So we need higher level >>> of abstraction. >>> >> >> I see, this seems a trade off between flexibility and usability. If >> application has access to _monitor_ APIs, they can be more flexible to >> implement their own logic. > > OK. > >> >> Another option can be application provides the policy with an API and >> monitor API used to realize the policy, but for this case it can be >> challenge to find and implement correct policies. > > OK. If we can enumerate the policies, then it will be ideal. > On plus side, there will not be any changes in needed in lib/power/ >
If we are talking about a power framework that user defines policies, I expect parsing/defining policies will be in the power library and will require changes in the power library anyway. But as mentioned above it is difficult to define a proper policy, this is not really related to eventdev, more a power library issue. We can continue to provide flexibility to user in eventdev and discuss the policy if a wider forum. > >> >>>> >>>> For the PMDs benefit from HW event manager, just not implementing >>>> .get_monitor_addr() dev_ops will make them free from power related APIs. >>> >>> But application fast path code gets diverged by exposing low level >>> primitives. >>> >> >> I am not clear with concern above, but for application that use default >> callbacks, 'rte_power_eventdev_pmgmt_port_enable()' needs to be called >> to enable this feature, if not called datapath is not impacted. >> And if not dequeue callback added at all, custom or default, data path >> is not impacted at all. > > Concerns are around following code[1] when callback is not registered > for this use case. > In eventdev, we are using _one packet at a time_ for a lot of use case > with latency critical workload like L1 processing. > On such cases, the following code will add up. > > [1] > cb = __atomic_load_n((void **)&fp_ops->ev_port.clbk[port_id], > __ATOMIC_RELAXED); > if (unlikely(cb != NULL)) > nb_rx = rte_event_dequeue_callbacks(dev_id, port_id, ev, nb_rx, cb); > > I see two options, > 1) Enumerate the power policy and let driver implement through > non-public PMD helper functions > OR > 2)Move the power management callback to driver via non-public PMD > helper functions to avoid cost of > PMDs where power managment done in HW and to remove above extra check > when NO callback is registered[1] > Got it, yes there is an additional check with event callbacks, we can add a compiler flag around it as done in ethdev to let it not compiled when not needed, will it work?
