Re: [dpdk-dev] [PATCH v2 1/6] eventdev: introduce event driven programming model

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

On Wed, Dec 14, 2016 at 03:19:22PM +0000, Bruce Richardson wrote:
> On Tue, Dec 06, 2016 at 09:22:15AM +0530, Jerin Jacob wrote:
> > In a polling model, lcores poll ethdev ports and associated
> > rx queues directly to look for packet. In an event driven model,
> > by contrast, lcores call the scheduler that selects packets for
> > them based on programmer-specified criteria. Eventdev library
> > adds support for event driven programming model, which offer
> > applications automatic multicore scaling, dynamic load balancing,
> > pipelining, packet ingress order maintenance and
> > synchronization services to simplify application packet processing.
> > 
> > By introducing event driven programming model, DPDK can support
> > both polling and event driven programming models for packet processing,
> > and applications are free to choose whatever model
> > (or combination of the two) that best suits their needs.
> > 
> > This patch adds the eventdev specification header file.
> > 
> > Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> > ---
> <snip>
> > + *
> > + * The *nb_events* parameter is the number of event objects to enqueue which are
> > + * supplied in the *ev* array of *rte_event* structure.
> > + *
> > + * The rte_event_enqueue_burst() function returns the number of
> > + * events objects it actually enqueued. A return value equal to *nb_events*
> > + * means that all event objects have been enqueued.
> > + *
> > + * @param dev_id
> > + *   The identifier of the device.
> > + * @param port_id
> > + *   The identifier of the event port.
> > + * @param ev
> > + *   Points to an array of *nb_events* objects of type *rte_event* structure
> > + *   which contain the event object enqueue operations to be processed.
> > + * @param nb_events
> > + *   The number of event objects to enqueue, typically number of
> > + *   rte_event_port_enqueue_depth() available for this port.
> > + *
> > + * @return
> > + *   The number of event objects actually enqueued on the event device. The
> > + *   return value can be less than the value of the *nb_events* parameter when
> > + *   the event devices queue is full or if invalid parameters are specified in a
> > + *   *rte_event*. If return value is less than *nb_events*, the remaining events
> > + *   at the end of ev[] are not consumed,and the caller has to take care of them
> > + *
> > + * @see rte_event_port_enqueue_depth()
> > + */
> > +uint16_t
> > +rte_event_enqueue_burst(uint8_t dev_id, uint8_t port_id, struct rte_event ev[],
> > +			uint16_t nb_events);
> > +
> One suggestion - do we want to make the ev[] array const, to disallow
> drivers from modifying the events passed in? Since the event structure
> is only 16B big, it should be small enough to be copied around in
> scheduler instances, allow the original events to remain unmodified.

Seems like a good idea to me. I will add it in v3.

> 
> /Bruce