[dpdk-dev] [PATCH v1 6/8] vhost: relax full barriers for used idx
Joyce Kong
joyce.kong at arm.com
Mon Dec 21 16:50:31 CET 2020
Used idx can be synchronized by one-way barrier instead of full
write barrier for split vring.
Signed-off-by: Joyce Kong <joyce.kong at arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>
---
lib/librte_vhost/vdpa.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lib/librte_vhost/vdpa.c b/lib/librte_vhost/vdpa.c
index ae6fdd24e..99a926a77 100644
--- a/lib/librte_vhost/vdpa.c
+++ b/lib/librte_vhost/vdpa.c
@@ -217,8 +217,8 @@ rte_vdpa_relay_vring_used(int vid, uint16_t qid, void *vring_m)
idx++;
}
- rte_smp_wmb();
- vq->used->idx = idx_m;
+ /* used idx is the synchronization point for the split vring */
+ __atomic_store_n(&vq->used->idx, idx_m, __ATOMIC_RELEASE);
if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX))
vring_used_event(s_vring) = idx_m;
--
2.29.2
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