Re: [dpdk-dev] [PATCH v2 1/3] eventdev: introduce adapter flags for periodic mode

[Shijith Thotton <shijith.thotton@gmail.com>]

On Tue, Mar 16, 2021 at 07:04:16PM +0000, Carrillo, Erik G wrote:
> Thanks, Shijith.  I'm posting a couple of follow-up comments in-line:
> 
> > -----Original Message-----
> > From: Shijith Thotton <sthotton@marvell.com>
> > Sent: Sunday, March 14, 2021 11:46 AM
> > To: Carrillo, Erik G <erik.g.carrillo@intel.com>
> > Cc: Shijith Thotton <sthotton@marvell.com>; Pavan Nikhilesh
> > <pbhagavatula@marvell.com>; Jerin Jacob <jerinj@marvell.com>;
> > dev@dpdk.org
> > Subject: [PATCH v2 1/3] eventdev: introduce adapter flags for periodic mode
> > 
> > A timer adapter in periodic mode can be used to arm periodic timers.
> > This patch adds flags used to advertise capability and configure timer adapter
> > in periodic mode. Capability flag should be set for adapters which support
> > periodic mode.
> > 
> > Below is a programming sequence on the usage:
> > 	/* check for periodic mode support by reading capability. */
> > 	rte_event_timer_adapter_caps_get(...);
> > 
> > 	/* create adapter in periodic mode by setting periodic flag
> > 	   (RTE_EVENT_TIMER_ADAPTER_F_PERIODIC) and resolution. */
> > 	rte_event_timer_adapter_create_ext(...);
> > 
> > 	/* arm periodic timer of configured resolution */
> > 	rte_event_timer_arm_burst(...);
> > 
> > 	/* timer event will be periodically generated at configured
> > 	   resolution till cancel is called. */
> > 	while (running) { rte_event_dequeue_burst(...); }
> > 
> > 	/* cancel periodic timer which stops generating events */
> > 	rte_event_timer_cancel_burst(...);
> > 
> > Signed-off-by: Shijith Thotton <sthotton@marvell.com>
> > ---
> >  doc/guides/prog_guide/event_timer_adapter.rst | 15 ++++++++++++++-
> > lib/librte_eventdev/rte_event_timer_adapter.h | 11 +++++++++++
> >  lib/librte_eventdev/rte_eventdev.h            |  3 +++
> >  3 files changed, 28 insertions(+), 1 deletion(-)
> > 
> > diff --git a/doc/guides/prog_guide/event_timer_adapter.rst
> > b/doc/guides/prog_guide/event_timer_adapter.rst
> > index a95efbe0d..0b2add6f7 100644
> > --- a/doc/guides/prog_guide/event_timer_adapter.rst
> > +++ b/doc/guides/prog_guide/event_timer_adapter.rst
> > @@ -138,6 +138,17 @@ This function is passed a callback function that will be
> > invoked if the  adapter needs to create an event port, giving the application
> > the opportunity  to control how it is done.
> > 
> > +Adapter modes
> > +^^^^^^^^^^^^^
> > +An event timer adapter can be configured in either periodic or
> > +non-periodic mode to support timers of respective type. A periodic
> 
> "...timers of the respective type..."
> 

Will change in v3.

> > +timer expires at a fixed time interval repeatedly till it is cancelled.
> > +A non-periodic timer expires only once. Periodic capability flag
> > +``RTE_EVENT_TIMER_ADAPTER_CAP_PERIODIC`` is set for adapters which
> > +support periodic mode. To configure an adapter in periodic mode,
> 
> "The periodic capability flag, ``RTE_EVENT_TIMER_ADAPTER_CAP_PERIODIC``, can be set for implementations that support periodic mode if desired."

Will change in v3.

> 
> > +``timer_adapter_flags`` of ``rte_event_timer_adapter_conf`` is set to
> > +include periodic flag ``RTE_EVENT_TIMER_ADAPTER_F_PERIODIC``.
> 
> "...include the periodic flag..."
> 

Will change in v3.

> > Maximum
> > +timeout
> > +(``max_tmo_nsec``) does not apply for periodic mode.
> > +
> >  Retrieve Event Timer Adapter Contextual Information
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >  The event timer adapter implementation may have constraints on tick
> > resolution @@ -229,7 +240,9 @@ Now we can arm the event timer with
> > ``rte_event_timer_arm_burst()``:
> > 
> >  Once an event timer expires, the application may free it or rearm it as
> > necessary.  If the application will rearm the timer, the state should be reset -
> > to RTE_EVENT_TIMER_NOT_ARMED by the application before rearming it.
> > +to RTE_EVENT_TIMER_NOT_ARMED by the application before rearming it.
> > +Timer expiry events will be generated once or periodically until the
> > +timer is cancelled based on adapter mode.
> > 
> >  Multiple Event Timers with Same Expiry Value
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > diff --git a/lib/librte_eventdev/rte_event_timer_adapter.h
> > b/lib/librte_eventdev/rte_event_timer_adapter.h
> > index d2ebcb090..b34dc1385 100644
> > --- a/lib/librte_eventdev/rte_event_timer_adapter.h
> > +++ b/lib/librte_eventdev/rte_event_timer_adapter.h
> > @@ -151,6 +151,12 @@ enum rte_event_timer_adapter_clk_src {
> >   * @see struct rte_event_timer_adapter_conf::flags
> >   */
> > 
> > +#define RTE_EVENT_TIMER_ADAPTER_F_PERIODIC	(1ULL << 2)
> > +/**< Flag to configure event timer adapter in periodic mode.
> 
> I think this could be elaborated on, perhaps like:
> 
> "Flag to configure an event timer adapter in periodic mode; non-periodic mode is the default.  A timer will fire once or periodically until the timer is cancelled based on the adapter mode."
> 

Sounds good. Will change in v3.

> > + *
> > + * @see struct rte_event_timer_adapter_conf::flags
> > + */
> > +
> >  /**
> >   * Timer adapter configuration structure
> >   */
> 
> <... snipped ...>
> 
> You should also be able to mark old versions of the series as superseded.  Also, there were a couple of coding style warnings on the second patch in the series regarding block comment syntax.
> 

Will do.

Thanks,
Shijith