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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 1/4] net/virtio: remove unnecessary rmb barrier
Date: Mon, 21 Dec 2020 22:23:18 +0800
Message-ID: <20201221142321.51606-2-joyce.kong@arm.com> (raw)
In-Reply-To: <20201221142321.51606-1-joyce.kong@arm.com>

As desc_is_used has a load-acquire or rte_io_rmb inside
and wait for used desc in virtqueue, it is ok to remove
virtio_rmb behind it.

Signed-off-by: Joyce Kong <joyce.kong@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
---
 drivers/net/virtio/virtio_ethdev.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 6c233b75b..0d91f7a50 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -209,12 +209,12 @@ virtio_send_command_packed(struct virtnet_ctl *cvq,
 	virtio_wmb(vq->hw->weak_barriers);
 	virtqueue_notify(vq);
 
-	/* wait for used descriptors in virtqueue */
+	/* wait for used desc in virtqueue
+	 * desc_is_used has a load-acquire or rte_io_rmb inside
+	 */
 	while (!desc_is_used(&desc[head], vq))
 		usleep(100);
 
-	virtio_rmb(vq->hw->weak_barriers);
-
 	/* now get used descriptors */
 	vq->vq_free_cnt += nb_descs;
 	vq->vq_used_cons_idx += nb_descs;
-- 
2.29.2


  reply	other threads:[~2020-12-21 14:24 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-21 14:23 [dpdk-dev] [PATCH v1 0/4] replace smp barriers in virtio with C11 atomic Joyce Kong
2020-12-21 14:23 ` Joyce Kong [this message]
2021-01-07 14:12   ` [dpdk-dev] [PATCH v1 1/4] net/virtio: remove unnecessary rmb barrier Maxime Coquelin
2020-12-21 14:23 ` [dpdk-dev] [PATCH v1 2/4] net/virtio: replace smp barrier with IO barrier Joyce Kong
2021-01-07 14:42   ` Maxime Coquelin
2020-12-21 14:23 ` [dpdk-dev] [PATCH v1 3/4] net/virtio: replace full barrier with relaxed barrier for Arm platform Joyce Kong
2021-01-07 14:47   ` Maxime Coquelin
2020-12-21 14:23 ` [dpdk-dev] [PATCH v1 4/4] net/virtio: replace full barrier with thread fence Joyce Kong
2021-01-07 16:28   ` Maxime Coquelin
2021-01-08  9:16 ` [dpdk-dev] [PATCH v1 0/4] replace smp barriers in virtio with C11 atomic Maxime Coquelin

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