On Tue, Jun 05, 2018 at 01:58:00PM +0200, Maxime Coquelin wrote: > On 06/05/2018 01:20 PM, Tiwei Bie wrote: > > On Tue, Jun 05, 2018 at 11:43:11AM +0200, Maxime Coquelin wrote: > > > On 06/05/2018 05:10 AM, Tiwei Bie wrote: > > > > On Mon, Jun 04, 2018 at 04:29:56PM +0200, Maxime Coquelin wrote: > > > > > On 06/04/2018 01:55 PM, Tiwei Bie wrote: > > > > > > On Fri, Jun 01, 2018 at 02:47:58PM +0200, Maxime Coquelin wrote: > > > > [...] > > > > > > > @@ -253,13 +246,15 @@ virtqueue_enqueue_xmit(struct virtnet_tx > > > > > > > *txvq, struct rte_mbuf *cookie, > > > > > > > struct virtio_net_hdr *hdr; > > > > > > > int offload; > > > > > > > - offload = tx_offload_enabled(vq->hw); > > > > > > > head_idx = vq->vq_desc_head_idx; > > > > > > > idx = head_idx; > > > > > > > dxp = &vq->vq_descx[idx]; > > > > > > > dxp->cookie = (void *)cookie; > > > > > > > dxp->ndescs = needed; > > > > > > > + offload = vq->hw->has_tx_offload && > > > > > > > + (cookie->ol_flags & PKT_TX_OFFLOAD_MASK); > > > > > > > > > > > > If features aren't negotiated, I think there is no need to > > > > > > check ol_flags and update the net header. > > > > > > > > > > Isn't what the code is doing? > > > > > has_tx_offload will be false if none of the Tx offload features have > > > > > been negotiated, so ol_flags won't be checked in that case. > > > > > > > > Hmm.. Somehow I treated 'and' as 'or'.. > > > > > > > > I have another question. When 'can_push' is false > > > > and 'vq->hw->has_tx_offload' is true, there will > > > > be a chance that virtio net hdr won't be zeroed > > > > when ol_flags doesn't specify any Tx offloads. > > > > > > Right, good catch. > > > It may be better to remove this small optimization. > > > Indeed, with the series, if the application does not enable offloads, > > > then the Virtio features are re-negotiated with the offload features. > > > > Yeah. It's a good idea to disable the features when > > the corresponding Tx offloads aren't requested by > > the applications! I like it! > > > > This issue happens for the mbufs whose ol_flags > > doesn't specify Tx offloads when applications > > enable Tx offloads and can_push is false. I think > > when applications enable Tx offloads, although > > most packets to be sent will have Tx offloads > > specified in their ol_flags, it's still possible > > that some packets don't have Tx offloads specified > > in their ol_flags. > > Reading again my reply, I think it wasn't clear enough, > let me rephrase it. > > My proposal is to keep disabling the features if the corresponding > Tx offloads aren't negotiated by the application, but just to remove the > check on mbuf's ol_flags, so: > offload = vq->hw->has_tx_offload; > > Doing that, we retrieve the old behaviour, i.e. if Virtio features are > negotiated but no ol_flags set, virtio-net header will be cleared.
It sounds good! Thanks! Best regards, Tiwei Bie
