> -----Original Message-----
> From: pbhagavat...@marvell.com <pbhagavat...@marvell.com>
> Sent: Tuesday, September 17, 2024 3:11 AM
> To: jer...@marvell.com; sthot...@marvell.com; Sevincer, Abdullah
> <abdullah.sevin...@intel.com>; hemant.agra...@nxp.com;
> sachin.sax...@oss.nxp.com; Van Haaren, Harry <harry.van.haa...@intel.com>;
> mattias.ronnb...@ericsson.com; lian...@liangbit.com; Mccarthy, Peter
> <peter.mccar...@intel.com>
> Cc: dev@dpdk.org; Pavan Nikhilesh <pbhagavat...@marvell.com>
> Subject: [PATCH v2 1/3] eventdev: introduce event pre-scheduling
>
> From: Pavan Nikhilesh <pbhagavat...@marvell.com>
>
> Event pre-scheduling improves scheduling performance by assigning events to
> event ports in advance when dequeues are issued.
> The dequeue operation initiates the pre-schedule operation, which completes in
> parallel without affecting the dequeued event flow contexts and dequeue
> latency.
>
Is the prescheduling done to get the event more quickly in the next dequeue?
The first dequeue executes pre-schedule to make events available for the next
dequeue.
Is this how it is supposed to work?
> Event devices can indicate pre-scheduling capabilities using
> `RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE` and
> `RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE_ADAPTIVE` via the event device
> info function `info.event_dev_cap`.
>
> Applications can select the pre-schedule type and configure it through
> `rte_event_dev_config.preschedule_type` during `rte_event_dev_configure`.
>
> The supported pre-schedule types are:
> * `RTE_EVENT_DEV_PRESCHEDULE_NONE` - No pre-scheduling.
> * `RTE_EVENT_DEV_PRESCHEDULE` - Always issue a pre-schedule on dequeue.
> * `RTE_EVENT_DEV_PRESCHEDULE_ADAPTIVE` - Delay issuing pre-schedule
> until
> there are no forward progress constraints with the held flow contexts.
>
> Signed-off-by: Pavan Nikhilesh <pbhagavat...@marvell.com>
> ---
> app/test/test_eventdev.c | 63 +++++++++++++++++++++
> doc/guides/prog_guide/eventdev/eventdev.rst | 22 +++++++
> lib/eventdev/rte_eventdev.h | 48 ++++++++++++++++
> 3 files changed, 133 insertions(+)
>
> diff --git a/app/test/test_eventdev.c b/app/test/test_eventdev.c index
> e4e234dc98..cf496ee88d 100644
> --- a/app/test/test_eventdev.c
> +++ b/app/test/test_eventdev.c
> @@ -1250,6 +1250,67 @@ test_eventdev_profile_switch(void)
> return TEST_SUCCESS;
> }
>
> +static int
> +preschedule_test(rte_event_dev_preschedule_type_t preschedule_type,
> +const char *preschedule_name) {
> +#define NB_EVENTS 1024
> + uint64_t start, total;
> + struct rte_event ev;
> + int rc, cnt;
> +
> + ev.event_type = RTE_EVENT_TYPE_CPU;
> + ev.queue_id = 0;
> + ev.op = RTE_EVENT_OP_NEW;
> + ev.u64 = 0xBADF00D0;
> +
> + for (cnt = 0; cnt < NB_EVENTS; cnt++) {
> + ev.flow_id = cnt;
> + rc = rte_event_enqueue_burst(TEST_DEV_ID, 0, &ev, 1);
> + TEST_ASSERT(rc == 1, "Failed to enqueue event");
> + }
> +
> + RTE_SET_USED(preschedule_type);
> + total = 0;
> + while (cnt) {
> + start = rte_rdtsc_precise();
> + rc = rte_event_dequeue_burst(TEST_DEV_ID, 0, &ev, 1, 0);
> + if (rc) {
> + total += rte_rdtsc_precise() - start;
> + cnt--;
> + }
> + }
> + printf("Preschedule type : %s, avg cycles %" PRIu64 "\n",
> preschedule_name,
> + total / NB_EVENTS);
> +
> + return TEST_SUCCESS;
> +}
> +
> +static int
> +test_eventdev_preschedule_configure(void)
> +{
> + struct rte_event_dev_config dev_conf;
> + struct rte_event_dev_info info;
> + int rc;
> +
> + rte_event_dev_info_get(TEST_DEV_ID, &info);
> +
> + if ((info.event_dev_cap & RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE)
> == 0)
> + return TEST_SKIPPED;
> +
> + devconf_set_default_sane_values(&dev_conf, &info);
> + dev_conf.preschedule_type = RTE_EVENT_DEV_PRESCHEDULE;
> + rc = rte_event_dev_configure(TEST_DEV_ID, &dev_conf);
> + TEST_ASSERT_SUCCESS(rc, "Failed to configure eventdev");
> +
> + rc = preschedule_test(RTE_EVENT_DEV_PRESCHEDULE_NONE,
> "RTE_EVENT_DEV_PRESCHEDULE_NONE");
> + rc |= preschedule_test(RTE_EVENT_DEV_PRESCHEDULE,
> "RTE_EVENT_DEV_PRESCHEDULE");
> + if (info.event_dev_cap &
> RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE_ADAPTIVE)
> + rc |=
> preschedule_test(RTE_EVENT_DEV_PRESCHEDULE_ADAPTIVE,
> +
> "RTE_EVENT_DEV_PRESCHEDULE_ADAPTIVE");
> +
> + return rc;
> +}
> +
> static int
> test_eventdev_close(void)
> {
> @@ -1310,6 +1371,8 @@ static struct unit_test_suite
> eventdev_common_testsuite = {
> test_eventdev_start_stop),
> TEST_CASE_ST(eventdev_configure_setup,
> eventdev_stop_device,
> test_eventdev_profile_switch),
> + TEST_CASE_ST(eventdev_configure_setup, NULL,
> + test_eventdev_preschedule_configure),
> TEST_CASE_ST(eventdev_setup_device, eventdev_stop_device,
> test_eventdev_link),
> TEST_CASE_ST(eventdev_setup_device, eventdev_stop_device,
> diff --git a/doc/guides/prog_guide/eventdev/eventdev.rst
> b/doc/guides/prog_guide/eventdev/eventdev.rst
> index fb6dfce102..341b9bb2c6 100644
> --- a/doc/guides/prog_guide/eventdev/eventdev.rst
> +++ b/doc/guides/prog_guide/eventdev/eventdev.rst
> @@ -357,6 +357,28 @@ Worker path:
> // Process the event received.
> }
>
> +Event Pre-scheduling
> +~~~~~~~~~~~~~~~~~~~~
> +
> +Event pre-scheduling improves scheduling performance by assigning
> +events to event ports in advance when dequeues are issued.
> +The `rte_event_dequeue_burst` operation initiates the pre-schedule
> +operation, which completes in parallel without affecting the dequeued event
> flow contexts and dequeue latency.
> +On the next dequeue operation, the pre-scheduled events are dequeued
> +and pre-schedule is initiated again.
> +
> +An application can use event pre-scheduling if the event device
> +supports it at either device level or at a individual port level.
> +The application can check pre-schedule capability by checking if
> +``rte_event_dev_info.event_dev_cap``
> +has the bit ``RTE_EVENT_DEV_CAP_PRESCHEDULE`` set, if present
> +pre-scheduling can be enabled at device configuration time by setting
> appropriate pre-schedule type in ``rte_event_dev_config.preschedule``.
> +
> +Currently, the following pre-schedule types are supported:
> + * ``RTE_EVENT_DEV_PRESCHEDULE_NONE`` - No pre-scheduling.
> + * ``RTE_EVENT_DEV_PRESCHEDULE`` - Always issue a pre-schedule when
> dequeue is issued.
> + * ``RTE_EVENT_DEV_PRESCHEDULE_ADAPTIVE`` - Issue pre-schedule when
> dequeue is issued and there are
> + no forward progress constraints.
> +
> Starting the EventDev
> ~~~~~~~~~~~~~~~~~~~~~
>
> diff --git a/lib/eventdev/rte_eventdev.h b/lib/eventdev/rte_eventdev.h index
> 08e5f9320b..5ea7f5a07b 100644
> --- a/lib/eventdev/rte_eventdev.h
> +++ b/lib/eventdev/rte_eventdev.h
> @@ -446,6 +446,30 @@ struct rte_event;
> * @see RTE_SCHED_TYPE_PARALLEL
> */
>
> +#define RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE (1ULL << 16) /**< Event
> +device supports event pre-scheduling.
> + *
> + * When this capability is available, the application can enable event
> +pre-scheduling on the event
> + * device to pre-schedule events to a event port when
> +`rte_event_dequeue_burst()`
> + * is issued.
> + * The pre-schedule process starts with the `rte_event_dequeue_burst()`
> +call and the
> + * pre-scheduled events are returned on the next `rte_event_dequeue_burst()`
> call.
> + *
> + * @see rte_event_dev_configure()
> + */
> +
> +#define RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE_ADAPTIVE (1ULL << 17)
> /**<
> +Event device supports adaptive event pre-scheduling.
> + *
> + * When this capability is available, the application can enable
> +adaptive pre-scheduling
> + * on the event device where the events are pre-scheduled when there
> +are no forward
> + * progress constraints with the currently held flow contexts.
> + * The pre-schedule process starts with the `rte_event_dequeue_burst()`
> +call and the
> + * pre-scheduled events are returned on the next `rte_event_dequeue_burst()`
> call.
> + *
> + * @see rte_event_dev_configure()
> + */
> +
> /* Event device priority levels */
> #define RTE_EVENT_DEV_PRIORITY_HIGHEST 0
> /**< Highest priority level for events and queues.
> @@ -680,6 +704,25 @@ rte_event_dev_attr_get(uint8_t dev_id, uint32_t
> attr_id,
> * @see rte_event_dequeue_timeout_ticks(), rte_event_dequeue_burst()
> */
>
> +typedef enum {
> + RTE_EVENT_DEV_PRESCHEDULE_NONE = 0,
> + /* Disable pre-schedule across the event device or on a given event
> port.
> + * @ref rte_event_dev_config.preschedule_type
> + */
> + RTE_EVENT_DEV_PRESCHEDULE,
> + /* Enable pre-schedule always across the event device or a given event
> port.
> + * @ref rte_event_dev_config.preschedule_type
> + * @see RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE
> + */
> + RTE_EVENT_DEV_PRESCHEDULE_ADAPTIVE,
> + /* Enable adaptive pre-schedule across the event device or a given event
> port.
> + * Delay issuing pre-schedule until there are no forward progress
> constraints with
> + * the held flow contexts.
> + * @ref rte_event_dev_config.preschedule_type
> + * @see RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE_ADAPTIVE
> + */
> +} rte_event_dev_preschedule_type_t;
> +
> /** Event device configuration structure */ struct rte_event_dev_config {
> uint32_t dequeue_timeout_ns;
> @@ -752,6 +795,11 @@ struct rte_event_dev_config {
> * optimized for single-link usage, this field is a hint for how many
> * to allocate; otherwise, regular event ports and queues will be used.
> */
> + rte_event_dev_preschedule_type_t preschedule_type;
> + /**< Event pre-schedule type to use across the event device, if
> supported.
> + * @see RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE
> + * @see RTE_EVENT_DEV_CAP_EVENT_PRESCHEDULE_ADAPTIVE
> + */
> };
>
> /**
> --
> 2.25.1
