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From: Ouyang Changchun <changchun.ouyang@intel.com>
To: dev@dpdk.org
Date: Mon, 9 Feb 2015 09:14:15 +0800
Message-Id: <1423444455-11330-27-git-send-email-changchun.ouyang@intel.com>
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Subject: [dpdk-dev] [PATCH v4 26/26] virtio: Fix updating vring descriptor
index issue
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Updating the vring descriptor index should be done before notifying host;
Remove 2 duplicated store memory barriers in both Rx and Tx path because there is
store memory barrier in vq_update_avail_idx function;
Notify the host only if packets actually transmitted(nb_tx > 0).
Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
---
lib/librte_pmd_virtio/virtio_rxtx.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/lib/librte_pmd_virtio/virtio_rxtx.c b/lib/librte_pmd_virtio/virtio_rxtx.c
index 0225cc9..1d74b34 100644
--- a/lib/librte_pmd_virtio/virtio_rxtx.c
+++ b/lib/librte_pmd_virtio/virtio_rxtx.c
@@ -555,15 +555,14 @@ virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
}
if (likely(nb_enqueued)) {
- virtio_wmb();
+ vq_update_avail_idx(rxvq);
+
if (unlikely(virtqueue_kick_prepare(rxvq))) {
virtqueue_notify(rxvq);
PMD_RX_LOG(DEBUG, "Notified\n");
}
}
- vq_update_avail_idx(rxvq);
-
return nb_rx;
}
@@ -719,14 +718,14 @@ virtio_recv_mergeable_pkts(void *rx_queue,
}
if (likely(nb_enqueued)) {
+ vq_update_avail_idx(rxvq);
+
if (unlikely(virtqueue_kick_prepare(rxvq))) {
virtqueue_notify(rxvq);
PMD_RX_LOG(DEBUG, "Notified");
}
}
- vq_update_avail_idx(rxvq);
-
return nb_rx;
}
@@ -800,14 +799,16 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
break;
}
}
- vq_update_avail_idx(txvq);
- virtio_wmb();
txvq->packets += nb_tx;
- if (unlikely(virtqueue_kick_prepare(txvq))) {
- virtqueue_notify(txvq);
- PMD_TX_LOG(DEBUG, "Notified backend after xmit");
+ if (likely(nb_tx)) {
+ vq_update_avail_idx(txvq);
+
+ if (unlikely(virtqueue_kick_prepare(txvq))) {
+ virtqueue_notify(txvq);
+ PMD_TX_LOG(DEBUG, "Notified backend after xmit");
+ }
}
return nb_tx;
--
1.8.4.2