On 13/12/17(Wed) 09:54, David Gwynne wrote:
> im still looking at vlan performance problems, as discussed by mpi@
> at http://www.grenadille.net/post/2017/02/13/What-happened-to-my-vlan.
>
> recently it occurred to me that we're making an implicit assumption
> that having the chip handle the injection of vlan tags has zero
> cost, and that all the loss in performance is purely a software
> problem. to test this assumption i knocked up the diff below to
> disable hw vlan tagging in ix(4), which was used in the tests mpi
> and hrvoje did.
>
> hrvoje tested this diff for me and noted a 10% improvement in pps
> when forwarding between vlan interfaces on ix(4). to quote hrvoje:
>
> without diff
> send - receive
> vlan - vlan = 830Kpps
>
> with diff
> send - receive
> vlan - vlan = 995Kpps
>
> my conclusion is that assumption that nics are fast at offloads is
> wrong. therefore id like to put this in. unfortunately 10% doesnt
> account for the entire loss in forwarding over vlan, but it does
> help a bit.
>
> would anyone else like to test? or ok it?
I don't have hardware to test but I'd like to add that in bridge(4)
scenario hardware tagging also decrease performance.
>From my point of view removing this per-chip option makes the stack
simpler, so I'm all for it. However I'd like to hear more test reports
on different ix(4) models.
> Index: if_ix.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/pci/if_ix.c,v
> retrieving revision 1.152
> diff -u -p -r1.152 if_ix.c
> --- if_ix.c 22 Jun 2017 02:44:37 -0000 1.152
> +++ if_ix.c 12 Dec 2017 23:39:41 -0000
> @@ -154,8 +154,6 @@ void ixgbe_set_ivar(struct ix_softc *, u
> void ixgbe_configure_ivars(struct ix_softc *);
> uint8_t *ixgbe_mc_array_itr(struct ixgbe_hw *, uint8_t **, uint32_t *);
>
> -void ixgbe_setup_vlan_hw_support(struct ix_softc *);
> -
> /* Support for pluggable optic modules */
> void ixgbe_setup_optics(struct ix_softc *);
> void ixgbe_handle_mod(struct ix_softc *);
> @@ -702,9 +700,6 @@ ixgbe_init(void *arg)
> IXGBE_WRITE_REG(&sc->hw, IXGBE_RDT(i), rxr->last_desc_filled);
> }
>
> - /* Set up VLAN support and filter */
> - ixgbe_setup_vlan_hw_support(sc);
> -
> /* Enable Receive engine */
> rxctrl = IXGBE_READ_REG(&sc->hw, IXGBE_RXCTRL);
> if (sc->hw.mac.type == ixgbe_mac_82598EB)
> @@ -1621,10 +1616,6 @@ ixgbe_setup_interface(struct ix_softc *s
>
> ifp->if_capabilities = IFCAP_VLAN_MTU;
>
> -#if NVLAN > 0
> - ifp->if_capabilities |= IFCAP_VLAN_HWTAGGING;
> -#endif
> -
> #ifdef IX_CSUM_OFFLOAD
> ifp->if_capabilities |= IFCAP_CSUM_TCPv4 | IFCAP_CSUM_UDPv4;
> #endif
> @@ -2922,12 +2913,6 @@ ixgbe_rxeof(struct ix_queue *que)
> /* first desc of a non-ps chain */
> sendmp = mp;
> sendmp->m_pkthdr.len = mp->m_len;
> -#if NVLAN > 0
> - if (staterr & IXGBE_RXD_STAT_VP) {
> - sendmp->m_pkthdr.ether_vtag = vtag;
> - sendmp->m_flags |= M_VLANTAG;
> - }
> -#endif
> }
>
> /* Pass the head pointer on */
> @@ -2989,44 +2974,6 @@ ixgbe_rx_checksum(uint32_t staterr, stru
> if (!(errors & IXGBE_RXD_ERR_TCPE))
> mp->m_pkthdr.csum_flags |=
> M_TCP_CSUM_IN_OK | M_UDP_CSUM_IN_OK;
> - }
> -}
> -
> -void
> -ixgbe_setup_vlan_hw_support(struct ix_softc *sc)
> -{
> - uint32_t ctrl;
> - int i;
> -
> - /*
> - * A soft reset zero's out the VFTA, so
> - * we need to repopulate it now.
> - */
> - for (i = 0; i < IXGBE_VFTA_SIZE; i++) {
> - if (sc->shadow_vfta[i] != 0)
> - IXGBE_WRITE_REG(&sc->hw, IXGBE_VFTA(i),
> - sc->shadow_vfta[i]);
> - }
> -
> - ctrl = IXGBE_READ_REG(&sc->hw, IXGBE_VLNCTRL);
> -#if 0
> - /* Enable the Filter Table if enabled */
> - if (ifp->if_capenable & IFCAP_VLAN_HWFILTER) {
> - ctrl &= ~IXGBE_VLNCTRL_CFIEN;
> - ctrl |= IXGBE_VLNCTRL_VFE;
> - }
> -#endif
> - if (sc->hw.mac.type == ixgbe_mac_82598EB)
> - ctrl |= IXGBE_VLNCTRL_VME;
> - IXGBE_WRITE_REG(&sc->hw, IXGBE_VLNCTRL, ctrl);
> -
> - /* On 82599 the VLAN enable is per/queue in RXDCTL */
> - if (sc->hw.mac.type != ixgbe_mac_82598EB) {
> - for (i = 0; i < sc->num_queues; i++) {
> - ctrl = IXGBE_READ_REG(&sc->hw, IXGBE_RXDCTL(i));
> - ctrl |= IXGBE_RXDCTL_VME;
> - IXGBE_WRITE_REG(&sc->hw, IXGBE_RXDCTL(i), ctrl);
> - }
> }
> }
>
>
