Agree Stephen. But rte_ring is not as basic as spinlock. IMO, existing note results in more questions than answers.
From: Stephen Hemminger <[email protected]> Sent: Tuesday, May 29, 2018 9:39 PM To: Honnappa Nagarahalli <[email protected]> Cc: Olivier Matz <[email protected]>; [email protected] Subject: Re: [dpdk-dev] [PATCH] rte_ring: clarify preemptable nature of ring algorithm Spinlock has same problem On Tue, May 29, 2018, 1:06 AM Honnappa Nagarahalli <[email protected]<mailto:[email protected]>> wrote: 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 <[email protected]<mailto:[email protected]>> Reviewed-by: Gavin Hu <[email protected]<mailto:[email protected]>> Reviewed-by: Ola Liljedahl <[email protected]<mailto:[email protected]>> --- 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 IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
