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b2a4654)
rte_ring implementation is not preemptible only under certain
circumstances. This clarification is helpful for data plane and
control plane communication using rte_ring.
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
Bypassing this constraint may cause the 2nd pthread to spin until the 1st one is scheduled again.
Moreover, if the 1st pthread is preempted by a context that has an higher priority, it may even cause a dead lock.
Bypassing this constraint may cause the 2nd pthread to spin until the 1st one is scheduled again.
Moreover, if the 1st pthread is preempted by a context that has an higher priority, it may even cause a dead lock.
- This does not mean it cannot be used, simply, there is a need to narrow down the situation when it is used by multi-pthread on the same core.
+ This means, use cases involving preemptible pthreads should consider using rte_ring carefully.
- 1. It CAN be used for any single-producer or single-consumer situation.
+ 1. It CAN be used for preemptible single-producer and single-consumer use case.
- 2. It MAY be used by multi-producer/consumer pthread whose scheduling policy are all SCHED_OTHER(cfs). User SHOULD be aware of the performance penalty before using it.
+ 2. It CAN be used for non-preemptible multi-producer and preemptible single-consumer use case.
- 3. It MUST not be used by multi-producer/consumer pthreads, whose scheduling policies are SCHED_FIFO or SCHED_RR.
+ 3. It CAN be used for preemptible single-producer and non-preemptible multi-consumer use case.
+
+ 4. It MAY be used by preemptible multi-producer and/or preemptible multi-consumer pthreads whose scheduling policy are all SCHED_OTHER(cfs), SCHED_IDLE or SCHED_BATCH. User SHOULD be aware of the performance penalty before using it.
+
+ 5. It MUST not be used by multi-producer/consumer pthreads, whose scheduling policies are SCHED_FIFO or SCHED_RR.
* - Bulk dequeue.
* - Bulk enqueue.
*
* - Bulk dequeue.
* - Bulk enqueue.
*
- * Note: the ring implementation is not preemptable. A lcore must not
- * be interrupted by another task that uses the same ring.
+ * Note: the ring implementation is not preemptible. Refer to Programmer's
+ * guide/Environment Abstraction Layer/Multiple pthread/Known Issues/rte_ring
+ * for more information.