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

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

On Wed, Nov 02, 2016 at 01:56:27PM +0000, Bruce Richardson wrote:
> On Wed, Nov 02, 2016 at 06:39:27PM +0530, Jerin Jacob wrote:
> > On Wed, Nov 02, 2016 at 11:35:51AM +0000, Bruce Richardson wrote:
> > > On Wed, Nov 02, 2016 at 04:55:22PM +0530, Jerin Jacob wrote:
> > > > On Fri, Oct 28, 2016 at 02:36:48PM +0530, Jerin Jacob wrote:
> > > > > On Fri, Oct 28, 2016 at 09:36:46AM +0100, Bruce Richardson wrote:
> > > > > > On Fri, Oct 28, 2016 at 08:31:41AM +0530, Jerin Jacob wrote:
> > > > > > > On Wed, Oct 26, 2016 at 01:54:14PM +0100, Bruce Richardson wrote:
> > > > > > > > On Wed, Oct 26, 2016 at 05:54:17PM +0530, Jerin Jacob wrote:
> > > > > > > How about making default as "mixed" and let application configures what
> > > > > > > is not required?. That way application responsibility is clear.
> > > > > > > something similar to ETH_TXQ_FLAGS_NOMULTSEGS, ETH_TXQ_FLAGS_NOREFCOUNT
> > > > > > > with default.
> > > > > > > 
> > > > > > I suppose it could work, but why bother doing that? If an app knows it's
> > > > > > only going to use one traffic type, why not let it just state what it
> > > > > > will do rather than try to specify what it won't do. If mixed is needed,
> > > > > 
> > > > > My thought was more inline with ethdev spec, like, ref-count is default,
> > > > > if application need exception then set ETH_TXQ_FLAGS_NOREFCOUNT. But it is OK, if
> > > > > you need other way.
> > > > > 
> > > > > > then it's easy enough to specify - and we can make it the zero/default
> > > > > > value too.
> > > > > 
> > > > > OK. Then we will make MIX as zero/default and add "allowed_event_types" in
> > > > > event queue config.
> > > > >
> > > > 
> > > > Bruce,
> > > > 
> > > > I have tried to make it as "allowed_event_types" in event queue config.
> > > > However, rte_event_queue_default_conf_get() can also take NULL for default
> > > > configuration. So I think, It makes sense to go with negation approach
> > > > like ethdev to define the default to avoid confusion on the default. So
> > > > I am thinking like below now,
> > > > 
> > > > ➜ [master][libeventdev] $ git diff
> > > > diff --git a/rte_eventdev.h b/rte_eventdev.h
> > > > index cf22b0e..cac4642 100644
> > > > --- a/rte_eventdev.h
> > > > +++ b/rte_eventdev.h
> > > > @@ -429,6 +429,12 @@ rte_event_dev_configure(uint8_t dev_id, struct
> > > > rte_event_dev_config *config);
> > > >   *
> > > >   *  \see rte_event_port_setup(), rte_event_port_link()
> > > >   */
> > > > +#define RTE_EVENT_QUEUE_CFG_NOATOMIC_TYPE      (1ULL << 1)
> > > > +/**< Skip configuring atomic schedule type resources */
> > > > +#define RTE_EVENT_QUEUE_CFG_NOORDERED_TYPE     (1ULL << 2)
> > > > +/**< Skip configuring ordered schedule type resources */
> > > > +#define RTE_EVENT_QUEUE_CFG_NOPARALLEL_TYPE    (1ULL << 3)
> > > > +/**< Skip configuring parallel schedule type resources */
> > > > 
> > > >  /** Event queue configuration structure */
> > > >  struct rte_event_queue_conf {
> > > > 
> > > > Thoughts?
> > > > 
> > > 
> > > I'm ok with the default as being all types, in the case where NULL is
> > > specified for the parameter. It does make the most sense.
> > 
> > Yes. That case I need to explicitly mention in the documentation about what
> > is default case. With RTE_EVENT_QUEUE_CFG_NOATOMIC_TYPE scheme it quite
> > understood what is default. Not adding up? :-)
> > 
> 
> Would below not work? DEFAULT explicitly stated, and can be commented to
> say all types allowed.

All I was trying to avoid explicitly stating the default state. Not worth
to have back and forth on slow path configuration, I will keep it as
positive logic as you suggested :-) and inspired from PKT_TX_L4_MASK

#define RTE_EVENT_QUEUE_CFG_TYPE_MASK       (3ULL << 0)
#define RTE_EVENT_QUEUE_CFG_ALL_TYPES       (0ULL << 0) /**< Enable all types */
#define RTE_EVENT_QUEUE_CFG_ATOMIC_ONLY     (1ULL << 0)
#define RTE_EVENT_QUEUE_CFG_ORDERED_ONLY    (2ULL << 0)
#define RTE_EVENT_QUEUE_CFG_PARALLEL_ONLY   (3ULL << 0)
#define RTE_EVENT_QUEUE_CFG_SINGLE_CONSUMER (1ULL << 2)

> 
> #define RTE_EVENT_QUEUE_CFG_DEFAULT 0
> #define RTE_EVENT_QUEUE_CFG_ALL_TYPES RTE_EVENT_QUEUE_CFG_DEFAULT
> #define RTE_EVENT_QUEUE_CFG_ATOMIC_ONLY (1<<0)
> #define RTE_EVENT_QUEUE_CFG_ORDERED_ONLY (1<<1) 
> ....
> 
> /Bruce