> -----Original Message----- > From: Maxime Coquelin <maxime.coque...@redhat.com> > Sent: 2022年6月8日 16:14 > To: Ma, WenwuX <wenwux...@intel.com>; dev@dpdk.org; > jasow...@redhat.com; Xia, Chenbo <chenbo....@intel.com>; > david.march...@redhat.com; Matz, Olivier <olivier.m...@6wind.com> > Cc: sta...@dpdk.org > Subject: Re: [PATCH 6/6] net/vhost: perform SW checksum in Tx path > > Hi Wenwu, > > On 6/6/22 11:44, Ma, WenwuX wrote: > > > > > >> -----Original Message----- > >> From: Maxime Coquelin <maxime.coque...@redhat.com> > >> Sent: 2022年6月2日 17:07 > >> To: Ma, WenwuX <wenwux...@intel.com>; dev@dpdk.org; > >> jasow...@redhat.com; Xia, Chenbo <chenbo....@intel.com>; > >> david.march...@redhat.com; Matz, Olivier <olivier.m...@6wind.com> > >> Cc: sta...@dpdk.org > >> Subject: Re: [PATCH 6/6] net/vhost: perform SW checksum in Tx path > >> > >> Hi Wenwu, > >> > >> Sorry, I missed your review. > >> > >> On 5/7/22 05:20, Ma, WenwuX wrote: > >>> > >>>> -----Original Message----- > >>>> From: Maxime Coquelin <maxime.coque...@redhat.com> > >>>> Sent: 2022年5月5日 18:27 > >>>> To: dev@dpdk.org; jasow...@redhat.com; Xia, Chenbo > >>>> <chenbo....@intel.com>; david.march...@redhat.com; > >>>> olivier.m...@6wind.com > >>>> Cc: sta...@dpdk.org; Maxime Coquelin > <maxime.coque...@redhat.com> > >>>> Subject: [PATCH 6/6] net/vhost: perform SW checksum in Tx path > >>>> > >>>> Virtio specification supports guest checksum offloading for L4, > >>>> which is enabled with VIRTIO_NET_F_GUEST_CSUM feature > negotiation. > >> However, > >>>> the Vhost PMD does not advertise Tx checksum offload capabilities. > >>>> > >>>> Advertising these offload capabilities at the ethdev level is not > >>>> enough, because we could still end-up with the application enabling > >>>> these offloads while the guest not negotiating it. > >>>> > >>>> This patch advertizes the Tx checksum offload capabilities, and > >>>> introduces a compatibility layer to cover the case > >>>> VIRTIO_NET_F_GUEST_CSUM has not been negotiated but the > >> application > >>>> does configure the Tx checksum offloads. This function performs the > >>>> L4 Tx > >> checksum in SW for UDP and TCP. > >>>> Compared to Rx SW checksum, the Tx SW checksum function needs to > >>>> compute the pseudo-header checksum, as we cannot knwo whether it > >> was > >>>> done before. > >>>> > >>>> This patch does not advertize SCTP checksum offloading capability > >>>> for now, but it could be handled later if the need arises. > >>> > >>> In virtio_enqueue_offload(), if RTE_MBUF_F_TX_IP_CKSUM is set, we > >>> will performs the L3 Tx checksum, why do not we advertise IPV4 > >>> checksum > >> offloading capability? > >>> Will we advertise it later? > >>> > >> > >> Indeed, we have an IPv4 SW checksum fallback in Vhost library. > >> We could think about adding the capability, but that's not urgent I > >> think. Do you have a use-case where it is needed? > >> > > The GRO/GSO library doesn't re-calculate IPv4 checksums for > merged/fragmented packets, it will cause iperf in the vm to fail. > > Can you please elaborate? > > If we don't expose the IPv4 checksum availability, it would be done by the > application using the Vhost PMD, so the result will be the same from the VM > point of view. Am I missing something? > Ok, it is not urgent.
> Thanks, > Maxime > > >> Regards, > >> Maxime > >
