Re: [dpdk-dev] [RFC] [PATCH v2] libeventdev: event driven programming model framework for DPDK

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

On Fri, Oct 14, 2016 at 03:00:57PM +0000, Eads, Gage wrote:
> Thanks Jerin, this looks good. I've put a few notes/questions inline.

Thanks Gage.

> 
> >  +
> >  +/**
> >  + * Get the device identifier for the named event device.
> >  + *
> >  + * @param name
> >  + *   Event device name to select the event device identifier.
> >  + *
> >  + * @return
> >  + *   Returns event device identifier on success.
> >  + *   - <0: Failure to find named event device.
> >  + */
> >  +extern uint8_t
> >  +rte_event_dev_get_dev_id(const char *name);
> 
> This return type should be int8_t, or some signed type, to support the failure case.

Makes sense. I will change to int to make consistent with rte_cryptodev_get_dev_id()

> 
> >  +};
> >  +
> >  +/**
> >  + * Schedule one or more events in the event dev.
> >  + *
> >  + * An event dev implementation may define this is a NOOP, for instance if
> >  + * the event dev performs its scheduling in hardware.
> >  + *
> >  + * @param dev_id
> >  + *   The identifier of the device.
> >  + */
> >  +extern void
> >  +rte_event_schedule(uint8_t dev_id);
> 
> One idea: Have the function return the number of scheduled packets (or 0 for implementations that do scheduling in hardware). This could be a helpful diagnostic for the software scheduler.

How about returning an implementation specific value ?
Rather than defining certain function associated with returned value.
Just to  make sure it works with all HW/SW implementations. Something like below,

/**
 * Schedule one or more events in the event dev.
 *
 * An event dev implementation may define this is a NOOP, for instance if
 * the event dev performs its scheduling in hardware.
 *
 * @param dev_id
 *   The identifier of the device.
 * @return
 *   Implementation specific value from the event driver for diagnostic purpose
 */
extern int
rte_event_schedule(uint8_t dev_id);