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From: Ouyang Changchun <changchun.ouyang@intel.com>
To: dev@dpdk.org
Subject: [dpdk-dev] [PATCH v4 02/26] virtio: Use weaker barriers
Date: Mon,  9 Feb 2015 09:13:51 +0800	[thread overview]
Message-ID: <1423444455-11330-3-git-send-email-changchun.ouyang@intel.com> (raw)
In-Reply-To: <1423444455-11330-1-git-send-email-changchun.ouyang@intel.com>

The DPDK driver only has to deal with the case of running on PCI
and with SMP. In this case, the code can use the weaker barriers
instead of using hard (fence) barriers. This will help performance.
The rationale is explained in Linux kernel virtio_ring.h.

To make it clearer that this is a virtio thing and not some generic
barrier, prefix the barrier calls with virtio_.

Add missing (and needed) barrier between updating ring data
structure and notifying host.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
---
 lib/librte_pmd_virtio/virtio_ethdev.c |  2 +-
 lib/librte_pmd_virtio/virtio_rxtx.c   |  8 +++++---
 lib/librte_pmd_virtio/virtqueue.h     | 19 ++++++++++++++-----
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/lib/librte_pmd_virtio/virtio_ethdev.c b/lib/librte_pmd_virtio/virtio_ethdev.c
index 662a49c..dc47e72 100644
--- a/lib/librte_pmd_virtio/virtio_ethdev.c
+++ b/lib/librte_pmd_virtio/virtio_ethdev.c
@@ -175,7 +175,7 @@ virtio_send_command(struct virtqueue *vq, struct virtio_pmd_ctrl *ctrl,
 		uint32_t idx, desc_idx, used_idx;
 		struct vring_used_elem *uep;
 
-		rmb();
+		virtio_rmb();
 
 		used_idx = (uint32_t)(vq->vq_used_cons_idx
 				& (vq->vq_nentries - 1));
diff --git a/lib/librte_pmd_virtio/virtio_rxtx.c b/lib/librte_pmd_virtio/virtio_rxtx.c
index c013f97..78af334 100644
--- a/lib/librte_pmd_virtio/virtio_rxtx.c
+++ b/lib/librte_pmd_virtio/virtio_rxtx.c
@@ -456,7 +456,7 @@ virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
 
 	nb_used = VIRTQUEUE_NUSED(rxvq);
 
-	rmb();
+	virtio_rmb();
 
 	num = (uint16_t)(likely(nb_used <= nb_pkts) ? nb_used : nb_pkts);
 	num = (uint16_t)(likely(num <= VIRTIO_MBUF_BURST_SZ) ? num : VIRTIO_MBUF_BURST_SZ);
@@ -516,6 +516,7 @@ virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
 	}
 
 	if (likely(nb_enqueued)) {
+		virtio_wmb();
 		if (unlikely(virtqueue_kick_prepare(rxvq))) {
 			virtqueue_notify(rxvq);
 			PMD_RX_LOG(DEBUG, "Notified\n");
@@ -547,7 +548,7 @@ virtio_recv_mergeable_pkts(void *rx_queue,
 
 	nb_used = VIRTQUEUE_NUSED(rxvq);
 
-	rmb();
+	virtio_rmb();
 
 	if (nb_used == 0)
 		return 0;
@@ -694,7 +695,7 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 	PMD_TX_LOG(DEBUG, "%d packets to xmit", nb_pkts);
 	nb_used = VIRTQUEUE_NUSED(txvq);
 
-	rmb();
+	virtio_rmb();
 
 	num = (uint16_t)(likely(nb_used < VIRTIO_MBUF_BURST_SZ) ? nb_used : VIRTIO_MBUF_BURST_SZ);
 
@@ -735,6 +736,7 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 		}
 	}
 	vq_update_avail_idx(txvq);
+	virtio_wmb();
 
 	txvq->packets += nb_tx;
 
diff --git a/lib/librte_pmd_virtio/virtqueue.h b/lib/librte_pmd_virtio/virtqueue.h
index fdee054..f6ad98d 100644
--- a/lib/librte_pmd_virtio/virtqueue.h
+++ b/lib/librte_pmd_virtio/virtqueue.h
@@ -46,9 +46,18 @@
 #include "virtio_ring.h"
 #include "virtio_logs.h"
 
-#define mb()  rte_mb()
-#define wmb() rte_wmb()
-#define rmb() rte_rmb()
+/*
+ * Per virtio_config.h in Linux.
+ *     For virtio_pci on SMP, we don't need to order with respect to MMIO
+ *     accesses through relaxed memory I/O windows, so smp_mb() et al are
+ *     sufficient.
+ *
+ * This driver is for virtio_pci on SMP and therefore can assume
+ * weaker (compiler barriers)
+ */
+#define virtio_mb()	rte_mb()
+#define virtio_rmb()	rte_compiler_barrier()
+#define virtio_wmb()	rte_compiler_barrier()
 
 #ifdef RTE_PMD_PACKET_PREFETCH
 #define rte_packet_prefetch(p)  rte_prefetch1(p)
@@ -225,7 +234,7 @@ virtqueue_full(const struct virtqueue *vq)
 static inline void
 vq_update_avail_idx(struct virtqueue *vq)
 {
-	rte_compiler_barrier();
+	virtio_rmb();
 	vq->vq_ring.avail->idx = vq->vq_avail_idx;
 }
 
@@ -255,7 +264,7 @@ static inline void
 virtqueue_notify(struct virtqueue *vq)
 {
 	/*
-	 * Ensure updated avail->idx is visible to host. mb() necessary?
+	 * Ensure updated avail->idx is visible to host.
 	 * For virtio on IA, the notificaiton is through io port operation
 	 * which is a serialization instruction itself.
 	 */
-- 
1.8.4.2

  parent reply	other threads:[~2015-02-09  1:14 UTC|newest]

Thread overview: 132+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-15  5:15 [dpdk-dev] [PATCH 00/22] Single virtio implementation Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 01/22] virtio: Rearrange resource initialization Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 02/22] virtio: Use weaker barriers Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 03/22] virtio: Allow starting with link down Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 04/22] virtio: Add support for Link State interrupt Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 05/22] ether: Add soft vlan encap/decap functions Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 06/22] virtio: Use software vlan stripping Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 07/22] virtio: Remove unnecessary adapter structure Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 08/22] virtio: Remove redundant vq_alignment Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 09/22] virtio: Fix how states are handled during initialization Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 10/22] virtio: Make vtpci_get_status local Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 11/22] virtio: Check for packet headroom at compile time Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 12/22] virtio: Move allocation before initialization Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 13/22] virtio: Add support for vlan filtering Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 14/22] virtio: Add suport for multiple mac addresses Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 15/22] virtio: Add ability to set MAC address Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 16/22] virtio: Free mbuf's with threshold Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 17/22] virtio: Use port IO to get PCI resource Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 18/22] virtio: Fix descriptor index issue Ouyang Changchun
2015-01-15 16:54   ` Stephen Hemminger
2015-01-16  0:55     ` Ouyang, Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 19/22] ether: Fix vlan strip/insert issue Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 20/22] example/vhost: Avoid inserting vlan twice Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 21/22] example/vhost: Add vlan-strip cmd line option Ouyang Changchun
2015-01-15  5:15 ` [dpdk-dev] [PATCH 22/22] virtio: Use soft vlan strip in mergeable Rx path Ouyang Changchun
2015-01-15 16:55   ` Stephen Hemminger
2015-01-16  0:56     ` Ouyang, Changchun
2015-01-27  2:35 ` [dpdk-dev] [PATCH v2 00/24] Single virtio implementation Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 01/24] virtio: Rearrange resource initialization Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 02/24] virtio: Use weaker barriers Ouyang Changchun
2015-01-27  7:03     ` Xie, Huawei
2015-01-27  9:58       ` Stephen Hemminger
2015-01-27 16:16         ` Xie, Huawei
2015-01-28  6:12           ` Ouyang, Changchun
2015-01-27  7:56     ` Xie, Huawei
2015-01-27  8:04       ` Ouyang, Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 03/24] virtio: Allow starting with link down Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 04/24] virtio: Add support for Link State interrupt Ouyang Changchun
2015-01-27  9:04     ` Xie, Huawei
2015-01-27 10:00       ` Stephen Hemminger
2015-01-28  3:03         ` Ouyang, Changchun
2015-01-28 15:11           ` Stephen Hemminger
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 05/24] ether: Add soft vlan encap/decap functions Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 06/24] virtio: Use software vlan stripping Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 07/24] virtio: Remove unnecessary adapter structure Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 08/24] virtio: Remove redundant vq_alignment Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 09/24] virtio: Fix how states are handled during initialization Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 10/24] virtio: Make vtpci_get_status local Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 11/24] virtio: Check for packet headroom at compile time Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 12/24] virtio: Move allocation before initialization Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 13/24] virtio: Add support for vlan filtering Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 14/24] virtio: Add suport for multiple mac addresses Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 15/24] virtio: Add ability to set MAC address Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 16/24] virtio: Free mbuf's with threshold Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 17/24] virtio: Use port IO to get PCI resource Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 18/24] virtio: Fix descriptor index issue Ouyang Changchun
2015-01-27  2:35   ` [dpdk-dev] [PATCH v2 19/24] ether: Fix vlan strip/insert issue Ouyang Changchun
2015-01-27  2:36   ` [dpdk-dev] [PATCH v2 20/24] example/vhost: Avoid inserting vlan twice Ouyang Changchun
2015-01-27  2:36   ` [dpdk-dev] [PATCH v2 21/24] example/vhost: Add vlan-strip cmd line option Ouyang Changchun
2015-01-27  2:36   ` [dpdk-dev] [PATCH v2 22/24] virtio: Use soft vlan strip in mergeable Rx path Ouyang Changchun
2015-01-27  2:36   ` [dpdk-dev] [PATCH v2 23/24] virtio: Fix zero copy break issue Ouyang Changchun
2015-01-27  2:36   ` [dpdk-dev] [PATCH v2 24/24] virtio: Remove hotspots Ouyang Changchun
2015-01-27  3:06   ` [dpdk-dev] [PATCH v2 00/24] Single virtio implementation Matthew Hall
2015-01-27  3:42     ` Wiles, Keith
2015-01-27  9:41       ` Matthew Hall
2015-01-27 10:02     ` Stephen Hemminger
2015-01-27 18:59       ` Matthew Hall
2015-01-29  7:23   ` [dpdk-dev] [PATCH v3 00/25] " Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 01/25] virtio: Rearrange resource initialization Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 02/25] virtio: Use weaker barriers Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 03/25] virtio: Allow starting with link down Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 04/25] virtio: Add support for Link State interrupt Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 05/25] ether: Add soft vlan encap/decap functions Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 06/25] virtio: Use software vlan stripping Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 07/25] virtio: Remove unnecessary adapter structure Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 08/25] virtio: Remove redundant vq_alignment Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 09/25] virtio: Fix how states are handled during initialization Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 10/25] virtio: Make vtpci_get_status local Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 11/25] virtio: Check for packet headroom at compile time Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 12/25] virtio: Move allocation before initialization Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 13/25] virtio: Add support for vlan filtering Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 14/25] virtio: Add suport for multiple mac addresses Ouyang Changchun
2015-01-29  7:23     ` [dpdk-dev] [PATCH v3 15/25] virtio: Add ability to set MAC address Ouyang Changchun
2015-01-29  7:24     ` [dpdk-dev] [PATCH v3 16/25] virtio: Free mbuf's with threshold Ouyang Changchun
2015-01-29  7:24     ` [dpdk-dev] [PATCH v3 17/25] virtio: Use port IO to get PCI resource Ouyang Changchun
2015-01-29 23:14       ` Thomas Monjalon
2015-02-04  1:31         ` Ouyang, Changchun
2015-01-29  7:24     ` [dpdk-dev] [PATCH v3 18/25] virtio: Fix descriptor index issue Ouyang Changchun
2015-01-29  7:24     ` [dpdk-dev] [PATCH v3 19/25] ether: Fix vlan strip/insert issue Ouyang Changchun
2015-02-04 10:54       ` Xie, Huawei
2015-02-05  0:54         ` Ouyang, Changchun
2015-01-29  7:24     ` [dpdk-dev] [PATCH v3 20/25] example/vhost: Avoid inserting vlan twice Ouyang Changchun
2015-01-29  7:24     ` [dpdk-dev] [PATCH v3 21/25] example/vhost: Add vlan-strip cmd line option Ouyang Changchun
2015-01-29  7:24     ` [dpdk-dev] [PATCH v3 22/25] virtio: Use soft vlan strip in mergeable Rx path Ouyang Changchun
2015-01-29  7:24     ` [dpdk-dev] [PATCH v3 23/25] virtio: Fix zero copy break issue Ouyang Changchun
2015-01-29  7:24     ` [dpdk-dev] [PATCH v3 24/25] virtio: Remove hotspots Ouyang Changchun
2015-01-29  7:24     ` [dpdk-dev] [PATCH v3 25/25] virtio: Fix wmb issue Ouyang Changchun
2015-02-09  1:13     ` [dpdk-dev] [PATCH v4 00/26] Single virtio implementation Ouyang Changchun
2015-02-09  1:13       ` [dpdk-dev] [PATCH v4 01/26] virtio: Rearrange resource initialization Ouyang Changchun
2015-02-09  1:13       ` Ouyang Changchun [this message]
2015-02-09  1:13       ` [dpdk-dev] [PATCH v4 03/26] virtio: Allow starting with link down Ouyang Changchun
2015-02-09  1:13       ` [dpdk-dev] [PATCH v4 04/26] virtio: Add support for Link State interrupt Ouyang Changchun
2015-02-09  1:13       ` [dpdk-dev] [PATCH v4 05/26] ether: Add soft vlan encap/decap functions Ouyang Changchun
2015-02-09  1:13       ` [dpdk-dev] [PATCH v4 06/26] virtio: Use software vlan stripping Ouyang Changchun
2015-02-09  1:13       ` [dpdk-dev] [PATCH v4 07/26] virtio: Remove unnecessary adapter structure Ouyang Changchun
2015-02-09  1:13       ` [dpdk-dev] [PATCH v4 08/26] virtio: Remove redundant vq_alignment Ouyang Changchun
2015-02-09  1:13       ` [dpdk-dev] [PATCH v4 09/26] virtio: Fix how states are handled during initialization Ouyang Changchun
2015-02-09  1:13       ` [dpdk-dev] [PATCH v4 10/26] virtio: Make vtpci_get_status local Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 11/26] virtio: Check for packet headroom at compile time Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 12/26] virtio: Move allocation before initialization Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 13/26] virtio: Add support for vlan filtering Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 14/26] virtio: Add suport for multiple mac addresses Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 15/26] virtio: Add ability to set MAC address Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 16/26] virtio: Free mbuf's with threshold Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 17/26] virtio: Use port IO to get PCI resource Ouyang Changchun
2015-02-11  4:32         ` Stephen Hemminger
2015-02-11  4:50           ` Ouyang, Changchun
2015-02-11  7:29             ` Vincent JARDIN
2015-02-11 13:50               ` Stephen Hemminger
2015-02-11 14:16                 ` Thomas Monjalon
2015-02-12  0:52                   ` Ouyang, Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 18/26] virtio: Fix descriptor index issue Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 19/26] ether: Fix vlan strip/insert issue Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 20/26] example/vhost: Avoid inserting vlan twice Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 21/26] example/vhost: Add vlan-strip cmd line option Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 22/26] virtio: Use soft vlan strip in mergeable Rx path Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 23/26] virtio: Fix zero copy break issue Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 24/26] virtio: Remove hotspots Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 25/26] virtio: Fix wmb issue Ouyang Changchun
2015-02-09  1:14       ` [dpdk-dev] [PATCH v4 26/26] virtio: Fix updating vring descriptor index issue Ouyang Changchun
2015-02-17  6:04       ` [dpdk-dev] [PATCH v4 00/26] Single virtio implementation Xie, Huawei
2015-02-20 18:06         ` Thomas Monjalon

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