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vhost: remove rte_memcpy from header copy

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First of all, rte_memcpy() is mostly useful for copying big packets
by leveraging hardware advanced instructions like AVX. But for virtio
net hdr, which is 12 bytes at most, invoking rte_memcpy() will not
introduce any performance boost.

And, to my suprise, rte_memcpy() is VERY huge. Since rte_memcpy()
is inlined, it increases the binary code size linearly every time
we call it at a different place. Replacing the two rte_memcpy()
with directly copy saves nearly 12K bytes of code size!

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
This commit is contained in:
Yuanhan Liu 2016-03-10 12:32:42 +08:00 committed by Thomas Monjalon
parent 932a00b85a
commit a98240621d
1 changed files with 12 additions and 4 deletions
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16
lib/librte_vhost/vhost_rxtx.c
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@ -129,6 +129,16 @@ virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
return;
}
static inline void
copy_virtio_net_hdr(struct vhost_virtqueue *vq, uint64_t desc_addr,
struct virtio_net_hdr_mrg_rxbuf hdr)
{
if (vq->vhost_hlen == sizeof(struct virtio_net_hdr_mrg_rxbuf))
*(struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)desc_addr = hdr;
else
*(struct virtio_net_hdr *)(uintptr_t)desc_addr = hdr.hdr;
}
static inline int __attribute__((always_inline))
copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
struct rte_mbuf *m, uint16_t desc_idx, uint32_t *copied)
@ -145,8 +155,7 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
rte_prefetch0((void *)(uintptr_t)desc_addr);
virtio_enqueue_offload(m, &virtio_hdr.hdr);
rte_memcpy((void *)(uintptr_t)desc_addr,
(const void *)&virtio_hdr, vq->vhost_hlen);
copy_virtio_net_hdr(vq, desc_addr, virtio_hdr);
vhost_log_write(dev, desc->addr, vq->vhost_hlen);
PRINT_PACKET(dev, (uintptr_t)desc_addr, vq->vhost_hlen, 0);
@ -444,8 +453,7 @@ copy_mbuf_to_desc_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
dev->device_fh, virtio_hdr.num_buffers);
virtio_enqueue_offload(m, &virtio_hdr.hdr);
rte_memcpy((void *)(uintptr_t)desc_addr,
(const void *)&virtio_hdr, vq->vhost_hlen);
copy_virtio_net_hdr(vq, desc_addr, virtio_hdr);
vhost_log_write(dev, vq->buf_vec[vec_idx].buf_addr, vq->vhost_hlen);
PRINT_PACKET(dev, (uintptr_t)desc_addr, vq->vhost_hlen, 0);