[dpdk-dev] [RFC PATCH 4/8] driver/virtio:enqueue TSO offload

Liu, Jijiang jijiang.liu at intel.com
Wed Sep 9 19:21:06 CEST 2015



> -----Original Message-----
> From: Ouyang, Changchun
> Sent: Tuesday, September 8, 2015 6:18 PM
> To: Liu, Jijiang; dev at dpdk.org
> Cc: Ouyang, Changchun
> Subject: RE: [dpdk-dev] [RFC PATCH 4/8] driver/virtio:enqueue TSO offload
> 
> 
> 
> > -----Original Message-----
> > From: Liu, Jijiang
> > Sent: Monday, September 7, 2015 2:11 PM
> > To: Ouyang, Changchun; dev at dpdk.org
> > Subject: RE: [dpdk-dev] [RFC PATCH 4/8] driver/virtio:enqueue TSO
> > offload
> >
> >
> >
> > > -----Original Message-----
> > > From: Ouyang, Changchun
> > > Sent: Monday, August 31, 2015 8:29 PM
> > > To: Liu, Jijiang; dev at dpdk.org
> > > Cc: Ouyang, Changchun
> > > Subject: RE: [dpdk-dev] [RFC PATCH 4/8] driver/virtio:enqueue TSO
> > > offload
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Jijiang Liu
> > > > Sent: Monday, August 31, 2015 5:42 PM
> > > > To: dev at dpdk.org
> > > > Subject: [dpdk-dev] [RFC PATCH 4/8] driver/virtio:enqueue TSO
> > > > offload
> > > >
> > > > Enqueue TSO4/6 offload.
> > > >
> > > > Signed-off-by: Jijiang Liu <jijiang.liu at intel.com>
> > > > ---
> > > >  drivers/net/virtio/virtio_rxtx.c |   23 +++++++++++++++++++++++
> > > >  1 files changed, 23 insertions(+), 0 deletions(-)
> > > >
> > > > diff --git a/drivers/net/virtio/virtio_rxtx.c
> > > > b/drivers/net/virtio/virtio_rxtx.c
> > > > index c5b53bb..4c2d838 100644
> > > > --- a/drivers/net/virtio/virtio_rxtx.c
> > > > +++ b/drivers/net/virtio/virtio_rxtx.c
> > > > @@ -198,6 +198,28 @@ virtqueue_enqueue_recv_refill(struct
> > > > virtqueue *vq, struct rte_mbuf *cookie)
> > > >  	return 0;
> > > >  }
> > > >
> > > > +static void
> > > > +virtqueue_enqueue_offload(struct virtqueue *txvq, struct rte_mbuf
> > *m,
> > > > +			uint16_t idx, uint16_t hdr_sz) {
> > > > +	struct virtio_net_hdr *hdr = (struct virtio_net_hdr *)(uintptr_t)
> > > > +				(txvq->virtio_net_hdr_addr + idx * hdr_sz);
> > > > +
> > > > +	if (m->tso_segsz != 0 && m->ol_flags & PKT_TX_TCP_SEG) {
> > > > +		if (m->ol_flags & PKT_TX_IPV4) {
> > > > +			if (!vtpci_with_feature(txvq->hw,
> > > > VIRTIO_NET_F_HOST_TSO4))
> > > > +				return;
> > >
> > > Do we need return error if host can't handle tso for the packet?
> > >
> > > > +			hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
> > > > +		} else if (m->ol_flags & PKT_TX_IPV6) {
> > > > +			if (!vtpci_with_feature(txvq->hw,
> > > > VIRTIO_NET_F_HOST_TSO6))
> > > > +				return;
> > >
> > > Same as above
> > >
> > > > +			hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
> > > > +		}
> > >
> > > Do we need else branch for the case of neither tcpv4 nor tcpv6?
> > >
> > > > +		hdr->gso_size = m->tso_segsz;
> > > > +		hdr->hdr_len = m->l2_len + m->l3_len + m->l4_len;
> > > > +	}
> > > > +}
> > > > +
> > > >  static int
> > > >  virtqueue_enqueue_xmit(struct virtqueue *txvq, struct rte_mbuf
> > > > *cookie) { @@ -221,6 +243,7 @@ virtqueue_enqueue_xmit(struct
> > > > virtqueue *txvq, struct rte_mbuf *cookie)
> > > >  	dxp->cookie = (void *)cookie;
> > > >  	dxp->ndescs = needed;
> > > >
> > > > +	virtqueue_enqueue_offload(txvq, cookie, idx, head_size);
> > >
> > > If TSO is not enabled in the feature bit, how to resolve here?
> >
> > The TSO enablement  check is in the function.
> >
> > If TSO is not enabled, and don't need to fill virtio_net_hdr now.
> 
> Here I mean if (m->ol_flags & PKT_TX_TCP_SEG) is true, that is to say, the virtio-
> pmd user expect do tso in vhost or virtio, but the host feature bit doesn't
> support it, then it should handle this case, either handle it in virtio pmd, or return
> error to caller.
> Otherwise the packet with flag tso maybe can't be send out normally.
> Am I right?
Not exactly, if host feature bit doesn't support TSO, and the TSO flag cannot been set in this function,
and then continue processing the packet in host. 
Now I think it had better return an error, and don't continue processing this packet.

> >
> > > >  	start_dp = txvq->vq_ring.desc;
> > > >  	start_dp[idx].addr =
> > > >  		txvq->virtio_net_hdr_mem + idx * head_size;
> > > > --
> > > > 1.7.7.6



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