[dpdk-dev] [PATCH] rte_ring: clarify preemptable nature of ring algorithm

Honnappa Nagarahalli honnappa.nagarahalli at arm.com
Tue May 29 07:06:13 CEST 2018


rte_ring implementation is not preemptable 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 at arm.com>
Reviewed-by: Gavin Hu <gavin.hu at arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl at arm.com>
---
 lib/librte_ring/rte_ring.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h
index d3d3f7f..2f9c945 100644
--- a/lib/librte_ring/rte_ring.h
+++ b/lib/librte_ring/rte_ring.h
@@ -26,8 +26,13 @@
  * - 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 can block threads from completing their
+ * operation under the following circumstances.
+ * A preempted thread can block other threads (operating on the same ring)
+ * from completing their operations, only if those threads are performing
+ * the same ring operation (enqueue/dequeue) as the preempted thread.
+ * In other words, a preempted consumer thread will not block any producer
+ * threads and vice versa.
  *
  */
 
-- 
2.7.4



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