From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v4 8/8] virtio/lib:add guest offload handle
Date: Wed, 11 Nov 2015 11:19:32 +0100 [thread overview]
Message-ID: <3146122.45QdW36GMG@xps13> (raw)
In-Reply-To: <20151111082318.GY2326@yliu-dev.sh.intel.com>
Yuanhan,
You deserve a "review award"!
Thanks a lot
2015-11-11 16:23, Yuanhan Liu:
> Regarding to your patch title, there are two minor pits:
>
> - the prefix should be "vhost" but not "virtio/lib".
>
> - you should add an extra space after ":"
>
> On Wed, Nov 11, 2015 at 02:40:46PM +0800, Jijiang Liu wrote:
> > Enqueue guest offload(CSUM and TSO) handle.
>
> (ALL) Your patch lacks some explanation. And I don't think it's about
> guest offload handling, it's about setting the right offload fields for
> RX side, such as VIRTIO_NET_HDR_F_NEEDS_CSUM.
>
> And you need spend few words to state why that is required. Something
> like following might help others to review:
>
> For packet going through from one VM to another VM without passing
> the NIC, and the VM claiming that it supports checksum offload,
> no one will actually calculate the checksum, hence, the packet
> will be dropped at TCP layer, due to checksum validation is failed.
>
> However, for VM2VM case, there is no need to do checksum, for we
> think the data should be reliable enough, and setting VIRTIO_NET_HDR_F_NEEDS_CSUM
> at RX side will let the TCP layer to bypass the checksum validation,
> so that the RX side could receive the packet in the end.
>
> At RX side, the offload information is inherited from mbuf, which is
> in turn inherited from TX side. If we can still get those info at RX
> side, it means the packet is from another VM at same host. So, it's
> safe to set the VIRTIO_NET_HDR_F_NEEDS_CSUM, to skip checksum validation.
>
>
> > Signed-off-by: Jijiang Liu <jijiang.liu@intel.com>
> > ---
> > lib/librte_vhost/vhost_rxtx.c | 45 +++++++++++++++++++++++++++++++++++++++-
> > 1 files changed, 43 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
> > index 9e70990..468fed8 100644
> > --- a/lib/librte_vhost/vhost_rxtx.c
> > +++ b/lib/librte_vhost/vhost_rxtx.c
> > @@ -54,6 +54,42 @@ is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t qp_nb)
> > return (is_tx ^ (idx & 1)) == 0 && idx < qp_nb * VIRTIO_QNUM;
> > }
> >
> > +static void
> > +virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
> > +{
>
> As virtio_hdr is set per mbuf, you'd better reset net_hdr first before
> setting it. Otherwise, if this mbuf has no offload related stuff, you
> may still get a net_hdr with offload related fields set, due to last
> mbuf has that.
>
> I know the chance is rare, but it's for code logic.
>
>
> --yliu
prev parent reply other threads:[~2015-11-11 10:20 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-11 6:40 [dpdk-dev] [PATCH v4 0/8] add virtio offload support in us-vhost Jijiang Liu
2015-11-11 6:40 ` [dpdk-dev] [PATCH v4 1/8] driver/virtio:add virtual address for virtio net header Jijiang Liu
2015-11-11 6:40 ` [dpdk-dev] [PATCH v4 2/8] driver/virtio:record virtual address of " Jijiang Liu
2015-11-11 6:40 ` [dpdk-dev] [PATCH v4 3/8] virtio/lib:add vhost TX checksum support capabilities Jijiang Liu
2015-11-11 8:26 ` Yuanhan Liu
2015-11-11 17:31 ` Stephen Hemminger
2015-11-12 1:41 ` Yuanhan Liu
2015-11-11 6:40 ` [dpdk-dev] [PATCH v4 4/8] virtio/lib:dequeue vhost TX offload Jijiang Liu
2015-11-11 6:40 ` [dpdk-dev] [PATCH v4 5/8] sample/vhost:remove ip_hdr structure defination Jijiang Liu
2015-11-11 8:34 ` Yuanhan Liu
2015-11-11 10:05 ` Thomas Monjalon
2015-11-11 6:40 ` [dpdk-dev] [PATCH v4 6/8] examples/vhost:support TX offload in vhost sample Jijiang Liu
2015-11-11 6:40 ` [dpdk-dev] [PATCH v4 7/8] virtio/lib:add virtio guest offload capabilities Jijiang Liu
2015-11-11 8:31 ` Yuanhan Liu
2015-11-11 8:38 ` Liu, Jijiang
2015-11-11 8:44 ` Yuanhan Liu
2015-11-11 8:53 ` Liu, Jijiang
2015-11-11 8:57 ` Xu, Qian Q
2015-11-11 11:10 ` Liu, Jijiang
2015-11-11 10:08 ` Thomas Monjalon
2015-11-11 12:53 ` Yuanhan Liu
2015-11-11 6:40 ` [dpdk-dev] [PATCH v4 8/8] virtio/lib:add guest offload handle Jijiang Liu
2015-11-11 8:23 ` Yuanhan Liu
2015-11-11 10:19 ` Thomas Monjalon [this message]
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