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

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

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:
> > > > > On Wed, Oct 26, 2016 at 12:11:03PM +0000, Van Haaren, Harry wrote:
> > > > > > > -----Original Message-----
> > > > rte_event_queue_conf, with possible values:
> > > > * atomic
> > > > * ordered
> > > > * parallel
> > > > * mixed - allowing all 3 types. I think allowing 2 of three types might
> > > >     make things too complicated.
> > > > 
> > > > An open question would then be how to behave when the queue type and
> > > > requested event type conflict. We can either throw an error, or just
> > > > ignore the event type and always treat enqueued events as being of the
> > > > queue type. I prefer the latter, because it's faster not having to
> > > > error-check, and it pushes the responsibility on the app to know what
> > > > it's doing.
> > > 
> > > 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?

 
> /Jerin
> 
> > 
> > Our software implementation for now, only supports one type per queue -
> > which we suspect should meet a lot of use-cases. We'll have to see about
> > adding in mixed types in future.
> > 
> > /Bruce