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vhost: access header only if offloading is supported

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If offloading features are not negotiated, parsing the virtio header
is not needed.

Micro-benchmark with testpmd shows that the gain is +4% with indirect
descriptors, +1% when using direct descriptors.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
This commit is contained in:
Maxime Coquelin 2016-10-14 10:07:07 +02:00 committed by Yuanhan Liu
parent dbffbf80e9
commit c843af3aa1
1 changed files with 25 additions and 8 deletions
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33
lib/librte_vhost/virtio_net.c
View File

@ -555,6 +555,18 @@ rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
return virtio_dev_rx(dev, queue_id, pkts, count);
}
static inline bool
virtio_net_with_host_offload(struct virtio_net *dev)
{
if (dev->features &
(VIRTIO_NET_F_CSUM | VIRTIO_NET_F_HOST_ECN |
VIRTIO_NET_F_HOST_TSO4 | VIRTIO_NET_F_HOST_TSO6 |
VIRTIO_NET_F_HOST_UFO))
return true;
return false;
}
static void
parse_ethernet(struct rte_mbuf *m, uint16_t *l4_proto, void **l4_hdr)
{
@ -607,6 +619,9 @@ vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
void *l4_hdr = NULL;
struct tcp_hdr *tcp_hdr = NULL;
if (hdr->flags == 0 && hdr->gso_type == VIRTIO_NET_HDR_GSO_NONE)
return;
parse_ethernet(m, &l4_proto, &l4_hdr);
if (hdr->flags == VIRTIO_NET_HDR_F_NEEDS_CSUM) {
if (hdr->csum_start == (m->l2_len + m->l3_len)) {
@ -702,7 +717,7 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vring_desc *descs,
uint32_t mbuf_avail, mbuf_offset;
uint32_t cpy_len;
struct rte_mbuf *cur = m, *prev = m;
struct virtio_net_hdr *hdr;
struct virtio_net_hdr *hdr = NULL;
/* A counter to avoid desc dead loop chain */
uint32_t nr_desc = 1;
@ -715,8 +730,10 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vring_desc *descs,
if (unlikely(!desc_addr))
return -1;
hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
rte_prefetch0(hdr);
if (virtio_net_with_host_offload(dev)) {
hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
rte_prefetch0(hdr);
}
/*
* A virtio driver normally uses at least 2 desc buffers
@ -733,18 +750,18 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vring_desc *descs,
if (unlikely(!desc_addr))
return -1;
rte_prefetch0((void *)(uintptr_t)desc_addr);
desc_offset = 0;
desc_avail = desc->len;
nr_desc += 1;
PRINT_PACKET(dev, (uintptr_t)desc_addr, desc->len, 0);
} else {
desc_avail = desc->len - dev->vhost_hlen;
desc_offset = dev->vhost_hlen;
}
rte_prefetch0((void *)(uintptr_t)(desc_addr + desc_offset));
PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset), desc_avail, 0);
mbuf_offset = 0;
mbuf_avail = m->buf_len - RTE_PKTMBUF_HEADROOM;
while (1) {
@ -831,7 +848,7 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vring_desc *descs,
prev->data_len = mbuf_offset;
m->pkt_len += mbuf_offset;
if (hdr->flags != 0 || hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE)
if (hdr)
vhost_dequeue_offload(hdr, m);
return 0;