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From: Joyce Kong <joyce.kong@arm.com>
To: maxime.coquelin@redhat.com, chenbo.xia@intel.com,
	honnappa.nagarahalli@arm.com, ruifeng.wang@arm.com
Cc: dev@dpdk.org, nd@arm.com
Subject: [dpdk-dev] [PATCH v1 5/8] vhost: relax full barriers for desc flags
Date: Mon, 21 Dec 2020 23:50:30 +0800
Message-ID: <20201221155033.6771-6-joyce.kong@arm.com> (raw)
In-Reply-To: <20201221155033.6771-1-joyce.kong@arm.com>

Relax the full read barrier to one-way barrier for desc flags in
packed vring.

Signed-off-by: Joyce Kong <joyce.kong@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
---
 lib/librte_vhost/virtio_net.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index c912ae354..b779034dc 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -222,8 +222,9 @@ vhost_flush_dequeue_shadow_packed(struct virtio_net *dev,
 	struct vring_used_elem_packed *used_elem = &vq->shadow_used_packed[0];
 
 	vq->desc_packed[vq->shadow_last_used_idx].id = used_elem->id;
-	rte_smp_wmb();
-	vq->desc_packed[vq->shadow_last_used_idx].flags = used_elem->flags;
+	/* desc flags is the synchronization point for virtio packed vring */
+	__atomic_store_n(&vq->desc_packed[vq->shadow_last_used_idx].flags,
+			 used_elem->flags, __ATOMIC_RELEASE);
 
 	vhost_log_cache_used_vring(dev, vq, vq->shadow_last_used_idx *
 				   sizeof(struct vring_packed_desc),
-- 
2.29.2


  parent reply	other threads:[~2020-12-21 15:52 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-21 15:50 [dpdk-dev] [PATCH v1 0/8] replace smp barriers in vhost with C11 atomic Joyce Kong
2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 1/8] examples/vhost: relax memory ordering when enqueue/dequeue Joyce Kong
2021-01-07 16:33   ` Maxime Coquelin
2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 2/8] examples/vhost_blk: replace smp with thread fence Joyce Kong
2021-01-07 16:35   ` Maxime Coquelin
2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 3/8] vhost: remove unnecessary smp barrier for desc flags Joyce Kong
2021-01-07 16:38   ` Maxime Coquelin
2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 4/8] vhost: remove unnecessary smp barrier for avail idx Joyce Kong
2021-01-07 16:43   ` Maxime Coquelin
2020-12-21 15:50 ` Joyce Kong [this message]
2021-01-07 16:45   ` [dpdk-dev] [PATCH v1 5/8] vhost: relax full barriers for desc flags Maxime Coquelin
2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 6/8] vhost: relax full barriers for used idx Joyce Kong
2021-01-07 16:46   ` Maxime Coquelin
2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 7/8] vhost: replace smp with thread fence for packed vring Joyce Kong
2021-01-07 17:06   ` Maxime Coquelin
2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 8/8] vhost: replace smp with thread fence for control path Joyce Kong
2021-01-07 17:15   ` Maxime Coquelin
2021-01-08  9:16 ` [dpdk-dev] [PATCH v1 0/8] replace smp barriers in vhost with C11 atomic Maxime Coquelin

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