[dpdk-dev,v7,1/7] eventtimer: add event timer adapter API

Message ID 1520546046-6973-2-git-send-email-erik.g.carrillo@intel.com (mailing list archive)
State Superseded, archived
Delegated to: Jerin Jacob
Headers

Checks

Context Check Description
ci/checkpatch warning coding style issues
ci/Intel-compilation success Compilation OK

Commit Message

Carrillo, Erik G March 8, 2018, 9:54 p.m. UTC
  Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
Signed-off-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
---
 lib/librte_eventdev/Makefile                  |   1 +
 lib/librte_eventdev/rte_event_timer_adapter.h | 645 ++++++++++++++++++++++++++
 lib/librte_eventdev/rte_eventdev.h            |  41 +-
 3 files changed, 653 insertions(+), 34 deletions(-)
 create mode 100644 lib/librte_eventdev/rte_event_timer_adapter.h
  

Comments

Jerin Jacob March 12, 2018, 7:53 a.m. UTC | #1
-----Original Message-----
> Date: Thu, 8 Mar 2018 15:54:00 -0600
> From: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
> To: pbhagavatula@caviumnetworks.com
> CC: dev@dpdk.org, jerin.jacob@caviumnetworks.com, nipun.gupta@nxp.com,
>  hemant.agrawal@nxp.com
> Subject: [PATCH v7 1/7] eventtimer: add event timer adapter API
> X-Mailer: git-send-email 1.7.10

IMO, you can add some git commit description here.

> 
> Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
> Signed-off-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
> ---
>  lib/librte_eventdev/Makefile                  |   1 +
>  lib/librte_eventdev/rte_event_timer_adapter.h | 645 ++++++++++++++++++++++++++
>  lib/librte_eventdev/rte_eventdev.h            |  41 +-
>  3 files changed, 653 insertions(+), 34 deletions(-)
>  create mode 100644 lib/librte_eventdev/rte_event_timer_adapter.h
> 
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this structure may change without prior notice
> + *
> + * Timer adapter configuration structure
> + */
> +struct rte_event_timer_adapter_conf {
> +	uint8_t event_dev_id;
> +	/**< Event device identifier */
> +	uint16_t timer_adapter_id;
> +	/**< Event timer adapter identifier */
> +	uint32_t socket_id;
> +	/**< Identifer of socket from which to allocate memory for adapter */

s/Identifer/Identifier

> +	enum rte_event_timer_adapter_clk_src clk_src;
> +	/**< Clock source for timer adapter */
> +	uint64_t timer_tick_ns;
> +	/**< Timer adapter resolution in ns */
> +	uint64_t max_tmo_ns;
> +	/**< Maximum timer timeout(expiry) in ns */
> +	uint64_t nb_timers;
> +	/**< Total number of timers per adapter */
> +	uint64_t flags;
> +	/**< Timer adapter config flags (RTE_EVENT_TIMER_ADAPTER_F_*) */
> +};
> +/**
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice
> + *
> + * Set an event timer's initial state and initialize the event it carries.
> + *
> + * @param evtim
> + *   A pointer to an event timer structure.
> + */
> +void __rte_experimental
> +rte_event_timer_init(struct rte_event_timer *evtim);

Since it can be used in fastpath, How about making it as "static inline" function?
Any it is just setting some variables.

> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice
> + *
> + * Arm a burst of event timers with separate expiration timeout tick for each
> + * event timer.
> + *
> + * Before calling this function, the application allocates
> + * ``struct rte_event_timer`` objects from mempool or huge page backed
> + * application buffers of desired size. On successful allocation,
> + * application updates the `struct rte_event_timer`` attributes such as
> + * expiry event attributes, timeout ticks from now.
> + * This function submits the event timer arm requests to the event timer adapter
> + * and on expiry, the events will be injected to designated event queue.
> + *
> + * @param adapter
> + *   A pointer to an event timer adapter structure.
> + * @param evtims
> + *   Pointer to an array of objects of type *rte_event_timer* structure.
> + * @param nb_evtims
> + *   Number of event timers in the supplied array.
> + *
> + * @return
> + *   The number of successfully armed event timers. The return value can be less
> + *   than the value of the *nb_evtims* parameter. If the return value is less
> + *   than *nb_evtims*, the remaining event timers at the end of *evtims*
> + *   are not consumed, and the caller has to take care of them, and rte_errno
> + *   is set accordingly. Possible errno values include:
> + *   - EINVAL Invalid timer adapter, expiry event queue ID is invalid, or an
> + *   expiry event's sched type doesn't match the capabilities of the
> + *   destination event queue.
> + *   - EAGAIN Specified timer adapter is not running
> + *   - EALREADY A timer was encountered that was already armed
> + */
> +int __rte_experimental

To maintain the consistency across eventdev and other subsystems in DPDK.
We could return uint16_t for all the fast path functions. ie. exiting
"int" error return can be changed to 

rte_errno = -EINVAL;
return 0;

This would avoid some series typecasting issues as well for the _retry_
case.

> +rte_event_timer_arm_burst(const struct rte_event_timer_adapter *adapter,
> +		struct rte_event_timer **evtims,
> +		uint16_t nb_evtims);
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice
> + *
> + * Arm a burst of event timers with same expiration timeout tick.
> + *
> + * Provides the same functionality as ``rte_event_timer_arm_burst()``, except
> + * that application can use this API when all the event timers have the
> + * same timeout expiration tick. This specialized function can provide the
> + * additional hint to the adapter implementation and optimize if possible.
> + *
> + * @param adapter
> + *   A pointer to an event timer adapter structure.
> + * @param evtims
> + *   Points to an array of objects of type *rte_event_timer* structure.
> + * @param timeout_ticks
> + *   The number of ticks in which the timers should expire.
> + * @param nb_evtims
> + *   Number of event timers in the supplied array.
> + *
> + * @return
> + *   The number of successfully armed event timers. The return value can be less
> + *   than the value of the *nb_evtims* parameter. If the return value is less
> + *   than *nb_evtims*, the remaining event timers at the end of *evtims*
> + *   are not consumed, and the caller has to take care of them, and rte_errno
> + *   is set accordingly. Possible errno values include:
> + *   - EINVAL Invalid timer adapter, expiry event queue ID is invalid, or an
> + *   expiry event's sched type doesn't match the capabilities of the
> + *   destination event queue.
> + *   - EAGAIN Specified event timer adapter is not running
> + *   - EALREADY A timer was encountered that was already armed
> + */
> +int __rte_experimental

Same as above

> +rte_event_timer_arm_tmo_tick_burst(
> +		const struct rte_event_timer_adapter *adapter,
> +		struct rte_event_timer **evtims,
> +		const uint64_t timeout_ticks,
> +		const uint16_t nb_evtims);
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice
> + *
> + * Cancel a burst of event timers from being scheduled to the event device.
> + *
> + * @param adapter
> + *   A pointer to an event timer adapter structure.
> + * @param evtims
> + *   Points to an array of objects of type *rte_event_timer* structure
> + * @param nb_evtims
> + *   Number of event timer instances in the supplied array.
> + *
> + * @return
> + *   The number of successfully canceled event timers. The return value can be
> + *   less than the value of the *nb_evtims* parameter. If the return value is
> + *   less than *nb_evtims*, the remaining event timers at the end of *evtims*
> + *   are not consumed, and the caller has to take care of them, and rte_errno
> + *   is set accordingly. Possible errno values include:
> + *   - EINVAL Invalid timer adapter identifier
> + *   - EAGAIN Specified timer adapter is not running
> + *   - EALREADY  A timer was encountered that was already canceled
> + */
> +int __rte_experimental

Same as above

> +rte_event_timer_cancel_burst(const struct rte_event_timer_adapter *adapter,
> +		struct rte_event_timer **evtims,
> +		uint16_t nb_evtims);
> +
> +#endif /* __RTE_EVENT_TIMER_ADAPTER_H__ */
> diff --git a/lib/librte_eventdev/rte_eventdev.h b/lib/librte_eventdev/rte_eventdev.h
> index b21c271..f9ad71e 100644
> --- a/lib/librte_eventdev/rte_eventdev.h
> +++ b/lib/librte_eventdev/rte_eventdev.h
> @@ -1,35 +1,8 @@
> -/*
> - *   BSD LICENSE
> - *
> - *   Copyright 2016 Cavium, Inc.
> - *   Copyright 2016 Intel Corporation.
> - *   Copyright 2016 NXP.
> - *
> - *   Redistribution and use in source and binary forms, with or without
> - *   modification, are permitted provided that the following conditions
> - *   are met:
> - *
> - *     * Redistributions of source code must retain the above copyright
> - *       notice, this list of conditions and the following disclaimer.
> - *     * Redistributions in binary form must reproduce the above copyright
> - *       notice, this list of conditions and the following disclaimer in
> - *       the documentation and/or other materials provided with the
> - *       distribution.
> - *     * Neither the name of Cavium, Inc nor the names of its
> - *       contributors may be used to endorse or promote products derived
> - *       from this software without specific prior written permission.
> - *
> - *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> - *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
> - *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
> - *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
> - *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
> - *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
> - *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> - *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> - *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> - *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> - *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2016 Cavium, Inc.
> + * Copyright(c) 2016-2018 Intel Corporation.
> + * Copyright(c) 2016 NXP.

Please send existing license changes as separate patch as we need to
get ACK from all vendors.

> + * All rights reserved.
>   */
>  
>  #ifndef _RTE_EVENTDEV_H_
> @@ -923,8 +896,8 @@ rte_event_dev_close(uint8_t dev_id);
>  /**< The event generated from ethdev subsystem */
>  #define RTE_EVENT_TYPE_CRYPTODEV        0x1
>  /**< The event generated from crypodev subsystem */
> -#define RTE_EVENT_TYPE_TIMERDEV         0x2
> -/**< The event generated from timerdev subsystem */
> +#define RTE_EVENT_TYPE_TIMER		0x2
> +/**< The event generated from event timer adapter */
>  #define RTE_EVENT_TYPE_CPU              0x3
>  /**< The event generated from cpu for pipelining.
>   * Application may use *sub_event_type* to further classify the event
> -- 
> 2.6.4

Other than above minor changes, It looks really good to me.
  
Carrillo, Erik G March 12, 2018, 4:22 p.m. UTC | #2
Hi Jerin,

Thanks for reviewing.  I've responded in-line:

> -----Original Message-----
> From: Jerin Jacob [mailto:jerin.jacob@caviumnetworks.com]
> Sent: Monday, March 12, 2018 2:54 AM
> To: Carrillo, Erik G <erik.g.carrillo@intel.com>
> Cc: pbhagavatula@caviumnetworks.com; dev@dpdk.org;
> nipun.gupta@nxp.com; hemant.agrawal@nxp.com
> Subject: Re: [PATCH v7 1/7] eventtimer: add event timer adapter API
> 
> -----Original Message-----
> > Date: Thu, 8 Mar 2018 15:54:00 -0600
> > From: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
> > To: pbhagavatula@caviumnetworks.com
> > CC: dev@dpdk.org, jerin.jacob@caviumnetworks.com,
> nipun.gupta@nxp.com,
> > hemant.agrawal@nxp.com
> > Subject: [PATCH v7 1/7] eventtimer: add event timer adapter API
> > X-Mailer: git-send-email 1.7.10
> 
> IMO, you can add some git commit description here.

Will do.

> 
> >
> > Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> > Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
> > Signed-off-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
> > ---
> >  lib/librte_eventdev/Makefile                  |   1 +
> >  lib/librte_eventdev/rte_event_timer_adapter.h | 645
> ++++++++++++++++++++++++++
> >  lib/librte_eventdev/rte_eventdev.h            |  41 +-
> >  3 files changed, 653 insertions(+), 34 deletions(-)  create mode
> > 100644 lib/librte_eventdev/rte_event_timer_adapter.h
> >
> > +
> > +/**
> > + * @warning
> > + * @b EXPERIMENTAL: this structure may change without prior notice
> > + *
> > + * Timer adapter configuration structure  */ struct
> > +rte_event_timer_adapter_conf {
> > +	uint8_t event_dev_id;
> > +	/**< Event device identifier */
> > +	uint16_t timer_adapter_id;
> > +	/**< Event timer adapter identifier */
> > +	uint32_t socket_id;
> > +	/**< Identifer of socket from which to allocate memory for adapter
> > +*/
> 
> s/Identifer/Identifier
>

Will fix.
 
> > +	enum rte_event_timer_adapter_clk_src clk_src;
> > +	/**< Clock source for timer adapter */
> > +	uint64_t timer_tick_ns;
> > +	/**< Timer adapter resolution in ns */
> > +	uint64_t max_tmo_ns;
> > +	/**< Maximum timer timeout(expiry) in ns */
> > +	uint64_t nb_timers;
> > +	/**< Total number of timers per adapter */
> > +	uint64_t flags;
> > +	/**< Timer adapter config flags (RTE_EVENT_TIMER_ADAPTER_F_*)
> */ };
> > +/**
> > +
> > +/**
> > + * @warning
> > + * @b EXPERIMENTAL: this API may change without prior notice
> > + *
> > + * Set an event timer's initial state and initialize the event it carries.
> > + *
> > + * @param evtim
> > + *   A pointer to an event timer structure.
> > + */
> > +void __rte_experimental
> > +rte_event_timer_init(struct rte_event_timer *evtim);
> 
> Since it can be used in fastpath, How about making it as "static inline"
> function?
> Any it is just setting some variables.
> 

Will do.

> > +
> > +/**
> > + * @warning
> > + * @b EXPERIMENTAL: this API may change without prior notice
> > + *
> > + * Arm a burst of event timers with separate expiration timeout tick
> > +for each
> > + * event timer.
> > + *
> > + * Before calling this function, the application allocates
> > + * ``struct rte_event_timer`` objects from mempool or huge page
> > +backed
> > + * application buffers of desired size. On successful allocation,
> > + * application updates the `struct rte_event_timer`` attributes such
> > +as
> > + * expiry event attributes, timeout ticks from now.
> > + * This function submits the event timer arm requests to the event
> > +timer adapter
> > + * and on expiry, the events will be injected to designated event queue.
> > + *
> > + * @param adapter
> > + *   A pointer to an event timer adapter structure.
> > + * @param evtims
> > + *   Pointer to an array of objects of type *rte_event_timer* structure.
> > + * @param nb_evtims
> > + *   Number of event timers in the supplied array.
> > + *
> > + * @return
> > + *   The number of successfully armed event timers. The return value can
> be less
> > + *   than the value of the *nb_evtims* parameter. If the return value is
> less
> > + *   than *nb_evtims*, the remaining event timers at the end of *evtims*
> > + *   are not consumed, and the caller has to take care of them, and
> rte_errno
> > + *   is set accordingly. Possible errno values include:
> > + *   - EINVAL Invalid timer adapter, expiry event queue ID is invalid, or an
> > + *   expiry event's sched type doesn't match the capabilities of the
> > + *   destination event queue.
> > + *   - EAGAIN Specified timer adapter is not running
> > + *   - EALREADY A timer was encountered that was already armed
> > + */
> > +int __rte_experimental
> 
> To maintain the consistency across eventdev and other subsystems in DPDK.
> We could return uint16_t for all the fast path functions. ie. exiting "int" error
> return can be changed to
> 
> rte_errno = -EINVAL;
> return 0;
> 
> This would avoid some series typecasting issues as well for the _retry_ case.

Sounds good.  I'll change the return type to uint16_t, but the errno behavior seems
to already be what you describe so I think we should be good there.

<... snipped ...>

> > - *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
> CONTRIBUTORS
> > - *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
> NOT
> > - *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
> FITNESS FOR
> > - *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
> COPYRIGHT
> > - *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
> INCIDENTAL,
> > - *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
> BUT NOT
> > - *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
> LOSS OF USE,
> > - *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
> AND ON ANY
> > - *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> > - *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
> OF THE USE
> > - *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
> DAMAGE.
> > +/* SPDX-License-Identifier: BSD-3-Clause
> > + * Copyright(c) 2016 Cavium, Inc.
> > + * Copyright(c) 2016-2018 Intel Corporation.
> > + * Copyright(c) 2016 NXP.
> 
> Please send existing license changes as separate patch as we need to get
> ACK from all vendors.
> 

Will do.

> > + * All rights reserved.
> >   */
> >
> >  #ifndef _RTE_EVENTDEV_H_
> > @@ -923,8 +896,8 @@ rte_event_dev_close(uint8_t dev_id);  /**< The
> > event generated from ethdev subsystem */
> >  #define RTE_EVENT_TYPE_CRYPTODEV        0x1
> >  /**< The event generated from crypodev subsystem */
> > -#define RTE_EVENT_TYPE_TIMERDEV         0x2
> > -/**< The event generated from timerdev subsystem */
> > +#define RTE_EVENT_TYPE_TIMER		0x2
> > +/**< The event generated from event timer adapter */
> >  #define RTE_EVENT_TYPE_CPU              0x3
> >  /**< The event generated from cpu for pipelining.
> >   * Application may use *sub_event_type* to further classify the event
> > --
> > 2.6.4
> 
> Other than above minor changes, It looks really good to me.

Thanks,
Gabriel
  

Patch

diff --git a/lib/librte_eventdev/Makefile b/lib/librte_eventdev/Makefile
index d27dd07..549b182 100644
--- a/lib/librte_eventdev/Makefile
+++ b/lib/librte_eventdev/Makefile
@@ -28,6 +28,7 @@  SYMLINK-y-include += rte_eventdev_pmd_pci.h
 SYMLINK-y-include += rte_eventdev_pmd_vdev.h
 SYMLINK-y-include += rte_event_ring.h
 SYMLINK-y-include += rte_event_eth_rx_adapter.h
+SYMLINK-y-include += rte_event_timer_adapter.h
 
 # versioning export map
 EXPORT_MAP := rte_eventdev_version.map
diff --git a/lib/librte_eventdev/rte_event_timer_adapter.h b/lib/librte_eventdev/rte_event_timer_adapter.h
new file mode 100644
index 0000000..1c8a45b
--- /dev/null
+++ b/lib/librte_eventdev/rte_event_timer_adapter.h
@@ -0,0 +1,645 @@ 
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2017 Cavium, Inc.
+ * Copyright(c) 2017-2018 Intel Corporation.
+ * All rights reserved.
+ */
+
+#ifndef __RTE_EVENT_TIMER_ADAPTER_H__
+#define __RTE_EVENT_TIMER_ADAPTER_H__
+
+/**
+ * @file
+ *
+ * RTE Event Timer Adapter
+ *
+ * An event timer adapter has the following abstract working model:
+ *
+ *                               timer_tick_ns
+ *                                   +
+ *                      +-------+    |
+ *                      |       |    |
+ *              +-------+ bkt 0 +----v---+
+ *              |       |       |        |
+ *              |       +-------+        |
+ *          +---+---+                +---+---+  +---+---+---+---+
+ *          |       |                |       |  |   |   |   |   |
+ *          | bkt n |                | bkt 1 |<-> t0| t1| t2| tn|
+ *          |       |                |       |  |   |   |   |   |
+ *          +---+---+                +---+---+  +---+---+---+---+
+ *              |     Timer adapter      |
+ *          +---+---+                +---+---+
+ *          |       |                |       |
+ *          | bkt 4 |                | bkt 2 |<--- Current bucket
+ *          |       |                |       |
+ *          +---+---+                +---+---+
+ *               |      +-------+       |
+ *               |      |       |       |
+ *               +------+ bkt 3 +-------+
+ *                      |       |
+ *                      +-------+
+ *
+ * - It has a virtual monotonically increasing 64-bit timer adapter clock based
+ *   on *enum rte_event_timer_adapter_clk_src* clock source. The clock source
+ *   could be a CPU clock, or a platform dependent external clock.
+ *
+ * - The application creates a timer adapter instance with given the clock
+ *   source, the total number of event timers, and a resolution(expressed in ns)
+ *   to traverse between the buckets.
+ *
+ * - Each timer adapter may have 0 to n buckets based on the configured
+ *   max timeout(max_tmo_ns) and resolution(timer_tick_ns). Upon starting the
+ *   timer adapter, the adapter starts ticking at *timer_tick_ns* resolution.
+ *
+ * - The application arms an event timer that will expire *timer_tick_ns*
+ *   from now.
+ *
+ * - The application can cancel an armed timer and no timer expiry event will be
+ *   generated.
+ *
+ * - If a timer expires then the library injects the timer expiry event in
+ *   the designated event queue.
+ *
+ * - The timer expiry event will be received through *rte_event_dequeue_burst*.
+ *
+ * - The application frees the timer adapter instance.
+ *
+ * Multiple timer adapters can be created with a varying level of resolution
+ * for various expiry use cases that run in parallel.
+ *
+ * Before using the timer adapter, the application has to create and configure
+ * an event device along with the event port. Based on the event device
+ * capability it might require creating an additional event port to be used
+ * by the timer adapter.
+ *
+ * The application creates the event timer adapter using the
+ * ``rte_event_timer_adapter_create()``. The event device id is passed to this
+ * function, inside this function the event device capability is checked,
+ * and if an in-built port is absent the application uses the default
+ * function to create a new producer port.
+ *
+ * The application may also use the function
+ * ``rte_event_timer_adapter_create_ext()`` to have granular control over
+ * producer port creation in a case where the in-built port is absent.
+ *
+ * After creating the timer adapter, the application has to start it
+ * using ``rte_event_timer_adapter_start()``. The buckets are traversed from
+ * 0 to n; when the adapter ticks, the next bucket is visited. Each time,
+ * the list per bucket is processed, and timer expiry events are sent to the
+ * designated event queue.
+ *
+ * The application can arm one or more event timers using the
+ * ``rte_event_timer_arm_burst()``. The *timeout_ticks* represents the number
+ * of *timer_tick_ns* after which the timer has to expire. The timeout at
+ * which the timers expire can be grouped or be independent of each
+ * event timer instance. ``rte_event_timer_arm_tmo_tick_burst()`` addresses the
+ * former case and ``rte_event_timer_arm_burst()`` addresses the latter case.
+ *
+ * The application can cancel the timers from expiring using the
+ * ``rte_event_timer_cancel_burst()``.
+ *
+ * On the secondary process, ``rte_event_timer_adapter_lookup()`` can be used
+ * to get the timer adapter pointer from its id and use it to invoke fastpath
+ * operations such as arm and cancel.
+ *
+ * Some of the use cases of event timer adapter are Beacon Timers,
+ * Generic SW Timeout, Wireless MAC Scheduling, 3G Frame Protocols,
+ * Packet Scheduling, Protocol Retransmission Timers, Supervision Timers.
+ * All these use cases require high resolution and low time drift.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <rte_spinlock.h>
+#include <rte_memory.h>
+
+#include "rte_eventdev.h"
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this enum may change without prior notice
+ *
+ * Timer adapter clock source
+ */
+enum rte_event_timer_adapter_clk_src {
+	RTE_EVENT_TIMER_ADAPTER_CPU_CLK,
+	/**< Use CPU clock as the clock source. */
+	RTE_EVENT_TIMER_ADAPTER_EXT_CLK0,
+	/**< Platform dependent external clock source 0. */
+	RTE_EVENT_TIMER_ADAPTER_EXT_CLK1,
+	/**< Platform dependent external clock source 1. */
+	RTE_EVENT_TIMER_ADAPTER_EXT_CLK2,
+	/**< Platform dependent external clock source 2. */
+	RTE_EVENT_TIMER_ADAPTER_EXT_CLK3,
+	/**< Platform dependent external clock source 3. */
+};
+
+#define RTE_EVENT_TIMER_ADAPTER_F_ADJUST_RES	(1ULL << 0)
+/**< The event timer adapter implementation may have constraints on the
+ * resolution (timer_tick_ns) and maximum timer expiry timeout(max_tmo_ns)
+ * based on the given timer adapter or system.  If this flag is set, the
+ * implementation adjusts the resolution and maximum timeout to the best
+ * possible configuration. On successful timer adapter creation, the
+ * application can get the configured resolution and max timeout with
+ * ``rte_event_timer_adapter_get_info()``.
+ *
+ * @see struct rte_event_timer_adapter_info::min_resolution_ns
+ * @see struct rte_event_timer_adapter_info::max_tmo_ns
+ */
+#define RTE_EVENT_TIMER_ADAPTER_F_SP_PUT	(1ULL << 1)
+/**< ``rte_event_timer_arm_burst()`` API to be used in single producer mode.
+ *
+ * @see struct rte_event_timer_adapter_conf::flags
+ */
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * Timer adapter configuration structure
+ */
+struct rte_event_timer_adapter_conf {
+	uint8_t event_dev_id;
+	/**< Event device identifier */
+	uint16_t timer_adapter_id;
+	/**< Event timer adapter identifier */
+	uint32_t socket_id;
+	/**< Identifer of socket from which to allocate memory for adapter */
+	enum rte_event_timer_adapter_clk_src clk_src;
+	/**< Clock source for timer adapter */
+	uint64_t timer_tick_ns;
+	/**< Timer adapter resolution in ns */
+	uint64_t max_tmo_ns;
+	/**< Maximum timer timeout(expiry) in ns */
+	uint64_t nb_timers;
+	/**< Total number of timers per adapter */
+	uint64_t flags;
+	/**< Timer adapter config flags (RTE_EVENT_TIMER_ADAPTER_F_*) */
+};
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * Event timer adapter stats structure
+ */
+struct rte_event_timer_adapter_stats {
+	uint64_t ev_enq_count;
+	/**< Eventdev enqueue count */
+	uint64_t ev_inv_count;
+	/**< Invalid expiry event count */
+	uint64_t evtim_retry_count;
+	/**< Event timer retry count */
+	uint64_t adapter_tick_count;
+	/**< Tick count for the adapter, at its resolution */
+};
+
+struct rte_event_timer_adapter;
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Callback function type for producer port creation.
+ */
+typedef int (*rte_event_timer_adapter_port_conf_cb_t)(uint16_t id,
+						      uint8_t event_dev_id,
+						      uint8_t *event_port_id,
+						      void *conf_arg);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Create an event timer adapter.
+ *
+ * This function must be invoked first before any other function in the API.
+ *
+ * @param conf
+ *   The event timer adapter configuration structure.
+ *
+ * @return
+ *   A pointer to the new allocated event timer adapter on success.
+ *   NULL on error with rte_errno set appropriately.
+ *   Possible rte_errno values include:
+ *   - ERANGE: timer_tick_ns is not in supported range.
+ *   - ENOMEM: unable to allocate sufficient memory for adapter instances
+ *   - EINVAL: invalid event device identifier specified in config
+ *   - ENOSPC: maximum number of adapters already created
+ *   - EIO: event device reconfiguration and restart error.  The adapter
+ *   reconfigures the event device with an additional port by default if it is
+ *   required to use a service to manage timers. If the device had been started
+ *   before this call, this error code indicates an error in restart following
+ *   an error in reconfiguration, i.e., a combination of the two error codes.
+ */
+struct rte_event_timer_adapter * __rte_experimental
+rte_event_timer_adapter_create(const struct rte_event_timer_adapter_conf *conf);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Create a timer adapter with the supplied callback.
+ *
+ * This function can be used to have a more granular control over the timer
+ * adapter creation.  If a built-in port is absent, then the function uses the
+ * callback provided to create and get the port id to be used as a producer
+ * port.
+ *
+ * @param conf
+ *   The timer adapter configuration structure
+ * @param conf_cb
+ *   The port config callback function.
+ * @param conf_arg
+ *   Opaque pointer to the argument for the callback function
+ *
+ * @return
+ *   A pointer to the new allocated event timer adapter on success.
+ *   NULL on error with rte_errno set appropriately.
+ *   Possible rte_errno values include:
+ *   - ERANGE: timer_tick_ns is not in supported range.
+ *   - ENOMEM: unable to allocate sufficient memory for adapter instances
+ *   - EINVAL: invalid event device identifier specified in config
+ *   - ENOSPC: maximum number of adapters already created
+ */
+struct rte_event_timer_adapter * __rte_experimental
+rte_event_timer_adapter_create_ext(
+		const struct rte_event_timer_adapter_conf *conf,
+		rte_event_timer_adapter_port_conf_cb_t conf_cb,
+		void *conf_arg);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * Timer adapter info structure.
+ */
+struct rte_event_timer_adapter_info {
+	uint64_t min_resolution_ns;
+	/**< Minimum timer adapter resolution in ns */
+	uint64_t max_tmo_ns;
+	/**< Maximum timer timeout(expire) in ns */
+	struct rte_event_timer_adapter_conf conf;
+	/**< Configured timer adapter attributes */
+	uint32_t caps;
+	/**< Event timer adapter capabilities */
+	int16_t event_dev_port_id;
+	/**< Event device port ID, if applicable */
+};
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Retrieve the contextual information of an event timer adapter.
+ *
+ * @param adapter
+ *   A pointer to the event timer adapter structure.
+ *
+ * @param[out] adapter_info
+ *   A pointer to a structure of type *rte_event_timer_adapter_info* to be
+ *   filled with the contextual information of the adapter.
+ *
+ * @return
+ *   - 0: Success, driver updates the contextual information of the
+ *   timer adapter
+ *   - <0: Error code returned by the driver info get function.
+ *   - -EINVAL: adapter identifier invalid
+ *
+ * @see RTE_EVENT_TIMER_ADAPTER_F_ADJUST_RES,
+ *   struct rte_event_timer_adapter_info
+ *
+ */
+int __rte_experimental
+rte_event_timer_adapter_get_info(
+		const struct rte_event_timer_adapter *adapter,
+		struct rte_event_timer_adapter_info *adapter_info);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Start a timer adapter.
+ *
+ * The adapter start step is the last one and consists of setting the timer
+ * adapter to start accepting the timers and schedules to event queues.
+ *
+ * On success, all basic functions exported by the API (timer arm,
+ * timer cancel and so on) can be invoked.
+ *
+ * @param adapter
+ *   A pointer to the event timer adapter structure.
+ *
+ * @return
+ *   - 0: Success, adapter started.
+ *   - <0: Error code returned by the driver start function.
+ *   - -EINVAL if adapter identifier invalid
+ */
+int __rte_experimental
+rte_event_timer_adapter_start(
+		const struct rte_event_timer_adapter *adapter);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Stop an event timer adapter.
+ *
+ * The adapter can be restarted with a call to
+ * ``rte_event_timer_adapter_start()``.
+ *
+ * @param adapter
+ *   A pointer to the event timer adapter structure.
+ *
+ * @return
+ *   - 0: Success, adapter stopped.
+ *   - <0: Error code returned by the driver stop function.
+ *   - -EINVAL if adapter identifier invalid
+ */
+int __rte_experimental
+rte_event_timer_adapter_stop(const struct rte_event_timer_adapter *adapter);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Lookup an event timer adapter using its identifier.
+ *
+ * If an event timer adapter was created in another process with the same
+ * identifier, this function will locate its state and set up access to it
+ * so that it can be used in this process.
+ *
+ * @param adapter_id
+ *  The event timer adapter identifier.
+ *
+ * @return
+ *  A pointer to the event timer adapter matching the identifier on success.
+ *  NULL on error with rte_errno set appropriately.
+ *  Possible rte_errno values include:
+ *   - ENOENT - requested entry not available to return.
+ */
+struct rte_event_timer_adapter * __rte_experimental
+rte_event_timer_adapter_lookup(uint16_t adapter_id);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Free an event timer adapter.
+ *
+ * Destroy an event timer adapter, freeing all resources.
+ *
+ * Before invoking this function, the application must wait for all the
+ * armed timers to expire or cancel the outstanding armed timers.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter structure.
+ *
+ * @return
+ *   - 0: Successfully freed the event timer adapter resources.
+ *   - <0: Failed to free the event timer adapter resources.
+ *   - -EAGAIN:  adapter is busy; timers outstanding
+ *   - -EBUSY: stop hasn't been called for this adapter yet
+ *   - -EINVAL: adapter id invalid, or adapter invalid
+ */
+int __rte_experimental
+rte_event_timer_adapter_free(struct rte_event_timer_adapter *adapter);
+
+/**
+ * Retrieve the service ID of the event timer adapter. If the adapter doesn't
+ * use an rte_service function, this function returns -ESRCH.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter.
+ *
+ * @param [out] service_id
+ *   A pointer to a uint32_t, to be filled in with the service id.
+ *
+ * @return
+ *   - 0: Success
+ *   - <0: Error code on failure
+ *   - -ESRCH: the adapter does not require a service to operate
+ */
+int __rte_experimental
+rte_event_timer_adapter_service_id_get(struct rte_event_timer_adapter *adapter,
+				       uint32_t *service_id);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Retrieve statistics for an event timer adapter instance.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter structure.
+ * @param[out] stats
+ *   A pointer to a structure to fill with statistics.
+ *
+ * @return
+ *   - 0: Successfully retrieved.
+ *   - <0: Failure; error code returned.
+ */
+int __rte_experimental
+rte_event_timer_adapter_stats_get(struct rte_event_timer_adapter *adapter,
+		struct rte_event_timer_adapter_stats *stats);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Reset statistics for an event timer adapter instance.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter structure.
+ *
+ * @return
+ *   - 0: Successfully reset;
+ *   - <0: Failure; error code returned.
+ */
+int __rte_experimental rte_event_timer_adapter_stats_reset(
+		struct rte_event_timer_adapter *adapter);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * Event timer state.
+ */
+enum rte_event_timer_state {
+	RTE_EVENT_TIMER_NOT_ARMED	= 0,
+	/**< Event timer not armed. */
+	RTE_EVENT_TIMER_ARMED		= 1,
+	/**< Event timer successfully armed. */
+	RTE_EVENT_TIMER_CANCELED	= 2,
+	/**< Event timer successfully canceled. */
+	RTE_EVENT_TIMER_ERROR		= -1,
+	/**< Generic event timer error. */
+	RTE_EVENT_TIMER_ERROR_TOOEARLY	= -2,
+	/**< Event timer timeout tick value is too small for the adapter to
+	 * handle, given its configured resolution.
+	 */
+	RTE_EVENT_TIMER_ERROR_TOOLATE	= -3,
+	/**< Event timer timeout tick is greater than the maximum timeout.*/
+};
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * The generic *rte_event_timer* structure to hold the event timer attributes
+ * for arm and cancel operations.
+ */
+RTE_STD_C11
+struct rte_event_timer {
+	struct rte_event ev;
+	/**<
+	 * Expiry event attributes.  On successful event timer timeout,
+	 * the following attributes will be used to inject the expiry event to
+	 * the eventdev:
+	 *  - event_queue_id: Targeted event queue id for expiry events.
+	 *  - event_priority: Event priority of the event expiry event in the
+	 *  event queue relative to other events.
+	 *  - sched_type: Scheduling type of the expiry event.
+	 *  - flow_id: Flow id of the expiry event.
+	 *  - op: RTE_EVENT_OP_NEW
+	 *  - event_type: RTE_EVENT_TYPE_TIMER
+	 */
+	volatile enum rte_event_timer_state state;
+	/**< State of the event timer. */
+	uint64_t timeout_ticks;
+	/**< Expiry timer ticks expressed in number of *timer_ticks_ns* from
+	 * now.
+	 * @see struct rte_event_timer_adapter_info::adapter_conf::timer_tick_ns
+	 */
+	uint64_t impl_opaque[2];
+	/**< Implementation-specific opaque data.
+	 * An event timer adapter implementation use this field to hold
+	 * implementation specific values to share between the arm and cancel
+	 * operations.  The application should not modify this field.
+	 */
+	uint8_t user_meta[];
+	/**< Memory to store user specific metadata.
+	 * The event timer adapter implementation should not modify this area.
+	 */
+} __rte_cache_aligned;
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Set an event timer's initial state and initialize the event it carries.
+ *
+ * @param evtim
+ *   A pointer to an event timer structure.
+ */
+void __rte_experimental
+rte_event_timer_init(struct rte_event_timer *evtim);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Arm a burst of event timers with separate expiration timeout tick for each
+ * event timer.
+ *
+ * Before calling this function, the application allocates
+ * ``struct rte_event_timer`` objects from mempool or huge page backed
+ * application buffers of desired size. On successful allocation,
+ * application updates the `struct rte_event_timer`` attributes such as
+ * expiry event attributes, timeout ticks from now.
+ * This function submits the event timer arm requests to the event timer adapter
+ * and on expiry, the events will be injected to designated event queue.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter structure.
+ * @param evtims
+ *   Pointer to an array of objects of type *rte_event_timer* structure.
+ * @param nb_evtims
+ *   Number of event timers in the supplied array.
+ *
+ * @return
+ *   The number of successfully armed event timers. The return value can be less
+ *   than the value of the *nb_evtims* parameter. If the return value is less
+ *   than *nb_evtims*, the remaining event timers at the end of *evtims*
+ *   are not consumed, and the caller has to take care of them, and rte_errno
+ *   is set accordingly. Possible errno values include:
+ *   - EINVAL Invalid timer adapter, expiry event queue ID is invalid, or an
+ *   expiry event's sched type doesn't match the capabilities of the
+ *   destination event queue.
+ *   - EAGAIN Specified timer adapter is not running
+ *   - EALREADY A timer was encountered that was already armed
+ */
+int __rte_experimental
+rte_event_timer_arm_burst(const struct rte_event_timer_adapter *adapter,
+		struct rte_event_timer **evtims,
+		uint16_t nb_evtims);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Arm a burst of event timers with same expiration timeout tick.
+ *
+ * Provides the same functionality as ``rte_event_timer_arm_burst()``, except
+ * that application can use this API when all the event timers have the
+ * same timeout expiration tick. This specialized function can provide the
+ * additional hint to the adapter implementation and optimize if possible.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter structure.
+ * @param evtims
+ *   Points to an array of objects of type *rte_event_timer* structure.
+ * @param timeout_ticks
+ *   The number of ticks in which the timers should expire.
+ * @param nb_evtims
+ *   Number of event timers in the supplied array.
+ *
+ * @return
+ *   The number of successfully armed event timers. The return value can be less
+ *   than the value of the *nb_evtims* parameter. If the return value is less
+ *   than *nb_evtims*, the remaining event timers at the end of *evtims*
+ *   are not consumed, and the caller has to take care of them, and rte_errno
+ *   is set accordingly. Possible errno values include:
+ *   - EINVAL Invalid timer adapter, expiry event queue ID is invalid, or an
+ *   expiry event's sched type doesn't match the capabilities of the
+ *   destination event queue.
+ *   - EAGAIN Specified event timer adapter is not running
+ *   - EALREADY A timer was encountered that was already armed
+ */
+int __rte_experimental
+rte_event_timer_arm_tmo_tick_burst(
+		const struct rte_event_timer_adapter *adapter,
+		struct rte_event_timer **evtims,
+		const uint64_t timeout_ticks,
+		const uint16_t nb_evtims);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Cancel a burst of event timers from being scheduled to the event device.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter structure.
+ * @param evtims
+ *   Points to an array of objects of type *rte_event_timer* structure
+ * @param nb_evtims
+ *   Number of event timer instances in the supplied array.
+ *
+ * @return
+ *   The number of successfully canceled event timers. The return value can be
+ *   less than the value of the *nb_evtims* parameter. If the return value is
+ *   less than *nb_evtims*, the remaining event timers at the end of *evtims*
+ *   are not consumed, and the caller has to take care of them, and rte_errno
+ *   is set accordingly. Possible errno values include:
+ *   - EINVAL Invalid timer adapter identifier
+ *   - EAGAIN Specified timer adapter is not running
+ *   - EALREADY  A timer was encountered that was already canceled
+ */
+int __rte_experimental
+rte_event_timer_cancel_burst(const struct rte_event_timer_adapter *adapter,
+		struct rte_event_timer **evtims,
+		uint16_t nb_evtims);
+
+#endif /* __RTE_EVENT_TIMER_ADAPTER_H__ */
diff --git a/lib/librte_eventdev/rte_eventdev.h b/lib/librte_eventdev/rte_eventdev.h
index b21c271..f9ad71e 100644
--- a/lib/librte_eventdev/rte_eventdev.h
+++ b/lib/librte_eventdev/rte_eventdev.h
@@ -1,35 +1,8 @@ 
-/*
- *   BSD LICENSE
- *
- *   Copyright 2016 Cavium, Inc.
- *   Copyright 2016 Intel Corporation.
- *   Copyright 2016 NXP.
- *
- *   Redistribution and use in source and binary forms, with or without
- *   modification, are permitted provided that the following conditions
- *   are met:
- *
- *     * Redistributions of source code must retain the above copyright
- *       notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above copyright
- *       notice, this list of conditions and the following disclaimer in
- *       the documentation and/or other materials provided with the
- *       distribution.
- *     * Neither the name of Cavium, Inc nor the names of its
- *       contributors may be used to endorse or promote products derived
- *       from this software without specific prior written permission.
- *
- *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2016 Cavium, Inc.
+ * Copyright(c) 2016-2018 Intel Corporation.
+ * Copyright(c) 2016 NXP.
+ * All rights reserved.
  */
 
 #ifndef _RTE_EVENTDEV_H_
@@ -923,8 +896,8 @@  rte_event_dev_close(uint8_t dev_id);
 /**< The event generated from ethdev subsystem */
 #define RTE_EVENT_TYPE_CRYPTODEV        0x1
 /**< The event generated from crypodev subsystem */
-#define RTE_EVENT_TYPE_TIMERDEV         0x2
-/**< The event generated from timerdev subsystem */
+#define RTE_EVENT_TYPE_TIMER		0x2
+/**< The event generated from event timer adapter */
 #define RTE_EVENT_TYPE_CPU              0x3
 /**< The event generated from cpu for pipelining.
  * Application may use *sub_event_type* to further classify the event