[dpdk-dev] [PATCH 2/3] net/virtio: allocate fake mbuf in Rx queue
Maxime Coquelin
maxime.coquelin at redhat.com
Mon Dec 21 17:14:55 CET 2020
While it is worth clarifying whether the fake mbuf
in virtnet_rx struct is really necessary, it is sure
that it heavily impacts cache usage by being part of
the struct. Indeed, it takes uses cachelines, and
requires alignement on a cacheline.
Before this series, it means it took 120 bytes in
virtnet_rx struct:
struct virtnet_rx {
struct virtqueue * vq; /* 0 8 */
/* XXX 56 bytes hole, try to pack */
/* --- cacheline 1 boundary (64 bytes) --- */
struct rte_mbuf fake_mbuf __attribute__((__aligned__(64))); /* 64 128 */
/* --- cacheline 3 boundary (192 bytes) --- */
This patch allocates it using malloc in order to optimize
virtnet_rx cache usage and so virtqueue cache usage.
Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
drivers/net/virtio/virtio_ethdev.c | 10 ++++++++++
drivers/net/virtio/virtio_rxtx.c | 8 +++-----
drivers/net/virtio/virtio_rxtx.h | 2 +-
3 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 297c01a70d..a1351b36ca 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -539,6 +539,7 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t queue_idx)
}
if (queue_type == VTNET_RQ) {
+ struct rte_mbuf *fake_mbuf;
size_t sz_sw = (RTE_PMD_VIRTIO_RX_MAX_BURST + vq_size) *
sizeof(vq->sw_ring[0]);
@@ -550,10 +551,18 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t queue_idx)
goto fail_q_alloc;
}
+ fake_mbuf = malloc(sizeof(*fake_mbuf));
+ if (!fake_mbuf) {
+ PMD_INIT_LOG(ERR, "can not allocate fake mbuf");
+ ret = -ENOMEM;
+ goto fail_q_alloc;
+ }
+
vq->sw_ring = sw_ring;
rxvq = &vq->rxq;
rxvq->port_id = dev->data->port_id;
rxvq->mz = mz;
+ rxvq->fake_mbuf = fake_mbuf;
} else if (queue_type == VTNET_TQ) {
txvq = &vq->txq;
txvq->port_id = dev->data->port_id;
@@ -636,6 +645,7 @@ virtio_free_queues(struct virtio_hw *hw)
queue_type = virtio_get_queue_type(hw, i);
if (queue_type == VTNET_RQ) {
+ free(vq->rxq.fake_mbuf);
rte_free(vq->sw_ring);
rte_memzone_free(vq->rxq.mz);
} else if (queue_type == VTNET_TQ) {
diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 1fcce36cbd..d147d7300a 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -703,11 +703,9 @@ virtio_dev_rx_queue_setup_finish(struct rte_eth_dev *dev, uint16_t queue_idx)
virtio_rxq_vec_setup(rxvq);
}
- memset(&rxvq->fake_mbuf, 0, sizeof(rxvq->fake_mbuf));
- for (desc_idx = 0; desc_idx < RTE_PMD_VIRTIO_RX_MAX_BURST;
- desc_idx++) {
- vq->sw_ring[vq->vq_nentries + desc_idx] =
- &rxvq->fake_mbuf;
+ memset(rxvq->fake_mbuf, 0, sizeof(*rxvq->fake_mbuf));
+ for (desc_idx = 0; desc_idx < RTE_PMD_VIRTIO_RX_MAX_BURST; desc_idx++) {
+ vq->sw_ring[vq->vq_nentries + desc_idx] = rxvq->fake_mbuf;
}
if (hw->use_vec_rx && !virtio_with_packed_queue(hw)) {
diff --git a/drivers/net/virtio/virtio_rxtx.h b/drivers/net/virtio/virtio_rxtx.h
index 7f1036be6f..6ce5d67d15 100644
--- a/drivers/net/virtio/virtio_rxtx.h
+++ b/drivers/net/virtio/virtio_rxtx.h
@@ -19,7 +19,7 @@ struct virtnet_stats {
struct virtnet_rx {
/* dummy mbuf, for wraparound when processing RX ring. */
- struct rte_mbuf fake_mbuf;
+ struct rte_mbuf *fake_mbuf;
uint64_t mbuf_initializer; /**< value to init mbufs. */
struct rte_mempool *mpool; /**< mempool for mbuf allocation */
--
2.29.2
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