From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: dev@dpdk.org, mst@redhat.com, jianfeng.tan@intel.com,
olivier.matz@6wind.com, stephen@networkplumber.org
Subject: Re: [dpdk-dev] [PATCH v2] vhost: Only access header if offloading is supported in dequeue path
Date: Tue, 11 Oct 2016 17:01:46 +0800 [thread overview]
Message-ID: <20161011090146.GP1597@yliu-dev.sh.intel.com> (raw)
In-Reply-To: <1476171927-10134-1-git-send-email-maxime.coquelin@redhat.com>
On Tue, Oct 11, 2016 at 09:45:27AM +0200, Maxime Coquelin wrote:
> @@ -684,12 +699,12 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vring_desc *descs,
> struct rte_mempool *mbuf_pool)
> {
> struct vring_desc *desc;
> - uint64_t desc_addr;
> + uint64_t desc_addr = 0;
> uint32_t desc_avail, desc_offset;
> 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;
>
> @@ -698,12 +713,14 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vring_desc *descs,
> (desc->flags & VRING_DESC_F_INDIRECT))
> return -1;
>
> - desc_addr = gpa_to_vva(dev, desc->addr);
> - if (unlikely(!desc_addr))
> - return -1;
> + if (virtio_net_with_host_offload(dev)) {
> + desc_addr = gpa_to_vva(dev, desc->addr);
> + if (unlikely(!desc_addr))
> + return -1;
>
> - hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
> - rte_prefetch0(hdr);
> + hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
> + rte_prefetch0(hdr);
> + }
>
> /*
> * A virtio driver normally uses at least 2 desc buffers
> @@ -720,18 +737,24 @@ 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 {
> + if (!desc_addr) {
> + desc_addr = gpa_to_vva(dev, desc->addr);
> + if (unlikely(!desc_addr))
> + return -1;
> + }
> +
I think this piece of code make things a bit complex. I think what you
want to achieve is, besides saving hdr prefetch, to save one call to
gpa_to_vva() for the non-ANY_LAYOUT case. Does that matter too much?
How about just saving the hdr prefetch?
if (virtio_net_with_host_offload(dev)) {
hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
rte_prefetch0(hdr);
}
--yliu
> 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) {
> @@ -795,7 +818,7 @@ 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 (virtio_net_with_host_offload(dev))
> vhost_dequeue_offload(hdr, m);
>
> return 0;
> --
> 2.7.4
next prev parent reply other threads:[~2016-10-11 9:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-06 17:00 [dpdk-dev] [PATCH] " Maxime Coquelin
2016-10-06 17:06 ` Maxime Coquelin
2016-10-11 7:45 ` [dpdk-dev] [PATCH v2] " Maxime Coquelin
2016-10-11 9:01 ` Yuanhan Liu [this message]
2016-10-14 7:24 ` Maxime Coquelin
2016-10-14 8:07 ` [dpdk-dev] [PATCH v3] " Maxime Coquelin
2016-10-18 14:30 ` Yuanhan Liu
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