Re: [dpdk-dev] [PATCH 1/3] evendev: fix inconsistency in event queue config

["Van Haaren, Harry" <harry.van.haaren@intel.com>]

> From: Pavan Nikhilesh [mailto:pbhagavatula@caviumnetworks.com]
> Sent: Thursday, October 12, 2017 2:16 PM
> To: jerin.jacob@caviumnetworks.com; hemant.agrawal@nxp.com; Van Haaren,
> Harry <harry.van.haaren@intel.com>
> Cc: dev@dpdk.org; Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
> Subject: [dpdk-dev] [PATCH 1/3] evendev: fix inconsistency in event queue
> config
> 
> With the current scheme of event queue configuration the cfg schedule
> type macros (RTE_EVENT_QUEUE_CFG_*_ONLY) are inconsistent with the
> event schedule type (RTE_SCHED_TYPE_*) this requires unnecessary
> conversion between the fastpath and slowpath API's while scheduling
> events or configuring event queues.
>
> This patch aims to fix such inconsistency by using event schedule
> types (RTE_SCHED_TYPE_*) for event queue configuration.

True - worth cleaning up.

 
> This patch also fixes example/eventdev_pipeline_sw_pmd as it doesn't
> convert RTE_EVENT_QUEUE_CFG_*_ONLY to RTE_SCHED_TYPE_* which leads to
> improper events being enqueued to the eventdev.
> 
> Fixes: adb5d5486c39 ("examples/eventdev_pipeline_sw_pmd: add sample app")
> 
> Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
>
>
>  app/test-eventdev/evt_common.h           | 21 -------------
>  app/test-eventdev/test_order_queue.c     |  4 +--
>  app/test-eventdev/test_perf_queue.c      |  4 +--
>  drivers/event/dpaa2/dpaa2_eventdev.c     |  4 +--
>  drivers/event/sw/sw_evdev.c              | 28 +++++------------
>  examples/eventdev_pipeline_sw_pmd/main.c | 18 +++++------
>  lib/librte_eventdev/rte_eventdev.c       | 20 +++++-------
>  lib/librte_eventdev/rte_eventdev.h       | 54 ++++++++++-------------------
> ---
>  test/test/test_eventdev.c                | 12 +++----
>  test/test/test_eventdev_sw.c             | 16 +++++-----
>  10 files changed, 60 insertions(+), 121 deletions(-)
> 
> diff --git a/app/test-eventdev/evt_common.h b/app/test-eventdev/evt_common.h
> index 4102076..ee896a2 100644
> --- a/app/test-eventdev/evt_common.h
> +++ b/app/test-eventdev/evt_common.h
> @@ -92,25 +92,4 @@ evt_has_all_types_queue(uint8_t dev_id)
>  			true : false;
>  }
> 
> -static inline uint32_t
> -evt_sched_type2queue_cfg(uint8_t sched_type)
> -{
> -	uint32_t ret;
> -
> -	switch (sched_type) {
> -	case RTE_SCHED_TYPE_ATOMIC:
> -		ret = RTE_EVENT_QUEUE_CFG_ATOMIC_ONLY;
> -		break;
> -	case RTE_SCHED_TYPE_ORDERED:
> -		ret = RTE_EVENT_QUEUE_CFG_ORDERED_ONLY;
> -		break;
> -	case RTE_SCHED_TYPE_PARALLEL:
> -		ret = RTE_EVENT_QUEUE_CFG_PARALLEL_ONLY;
> -		break;
> -	default:
> -		rte_panic("Invalid sched_type %d\n", sched_type);
> -	}
> -	return ret;
> -}


We should note here, that SCHED_TYPE are integer values:
#define RTE_SCHED_TYPE_ORDERED          0
#define RTE_SCHED_TYPE_ATOMIC           1
#define RTE_SCHED_TYPE_PARALLEL         2

While the EVENT_QUEUE_CFG_ types were bitmasks (before being removed in this patch)
#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_LINK        (1ULL << 2)


I'm not against this change - but we must be careful that if there was any bit-masking being used previously,
that that will subtly have broken if we change to sched types. I'm reviewing with that in mind..

The RTE_EVENT_QUEUE_CFG_ALL_TYPES  config flag now means that all SCHED_TYPEs
are valid. Previously this was contained in the bitmask.. this may lead to issues.

See patch 2/3, where *only* the schedule_type is read, and returned. What if it the "ALL_TYPES" flag is
set on the queue? It will be reported wrongly. Currently there is no integer value for "ALL_TYPES",
so we cannot represent "ALL TYPES" in the return value from get_attr().

Am I explaining my reasoning clearly enough? 


The patch correctly leaves QUEUE_CFG_SINGLE_LINK as a bitmask, so that bit is ok.



>  #endif /*  _EVT_COMMON_*/
> diff --git a/app/test-eventdev/test_order_queue.c b/app/test-
> eventdev/test_order_queue.c
> index beadd9c..1fa4082 100644


<snip> Remaining diff was updating the QUEUE_CFG to SCHED_TYPE </snip>