[ovs-dev] 答复: 答复: [PATCH v2] netdev-linux: Prepend the std packet in the TSO packet

Yi Yang (杨燚)-云服务集团 yangyi01 at inspur.com
Wed Feb 5 00:05:23 UTC 2020


Thanks Flavio, which kernel version can support TSO for tap device?

-----邮件原件-----
发件人: Flavio Leitner [mailto:fbl at sysclose.org] 
发送时间: 2020年2月5日 1:12
收件人: Yi Yang (杨燚)-云服务集团 <yangyi01 at inspur.com>
抄送: dev at openvswitch.org; i.maximets at ovn.org; txfh2007 at aliyun.com
主题: Re: [ovs-dev] 答复: [PATCH v2] netdev-linux: Prepend the std packet in the TSO packet

On Tue, Feb 04, 2020 at 12:00:19PM -0300, Flavio Leitner wrote:
> On Tue, Feb 04, 2020 at 12:51:24AM +0000, Yi Yang (杨 D)-云服务集团 wrote:
> > Hi, Flavio
> > 
> > With this one patch and previous several merged TSO-related patches, 
> > can veth work with "ethtool -K vethX tx on"? I always can't figure 
> > out why veth can work in dpdk data path when tx offload features are 
> > on, it looks like you're fixing this big issue, right?
> 
> If you have tso enabled with dpdk, then veth works with vethX tx on 
> (which is the default setting for veth). Otherwise TSO is not enabled 
> and then you need to turn tx offloading off.
> 
> You said "can work in dpdk data path when tx ... are on", so I think 
> it's okay? Not sure though.
> 
> > For tap interface, it can't support TSO, do you Redhat guys have 
> > plan to enable it on kernel side.
> 
> Yeah, currently it only works in one direction (OvS -> kernel). I am 
> looking into this now.

With TSO enabled on the TAP device:

Traffic Direction      TSO disabled         TSO enabled  
VM->tap                2.98 Gbits/sec       22.9 Gbits/sec
tap->VM                2.29 Gbits/sec       18.0 Gbits/sec

The code is in my github branch:
https://github.com/fleitner/ovs/tree/tso-tap-enable-tx-v1

commit 884371df3bf3df836d4c2ab2d62b420339691fe8
Author: Flavio Leitner <fbl at sysclose.org>
Date:   Tue Feb 4 11:18:49 2020 -0300

    netdev-linux: Enable TSO in the TAP device.
    
    Use ioctl TUNSETOFFLOAD if kernel supports to enable TSO
    offloading in the tap device.
    
    Fixes: 29cf9c1b3b9c ("userspace: Add TCP Segmentation Offload support")
    Signed-off-by: Flavio Leitner <fbl at sysclose.org>

Please try it out and let me know if it works for you as well.
Thanks
fbl


> VM->veth               2.96 Gbits/sec       22.6 Gbits/sec
> veth->VM               2.30 Gbits/sec       9.58 Gbits/sec



> See below my iperf3 results as a reference:
> 
> Traffic Direction      TSO disabled         TSO enabled  
> VM->tap                2.98 Gbits/sec       22.7 Gbits/sec
> VM->veth               2.96 Gbits/sec       22.6 Gbits/sec
> veth->VM               2.30 Gbits/sec       9.58 Gbits/sec
> tap->VM                2.29 Gbits/sec       2.19 Gbits/sec
> 
> fbl
>  
> > -----邮件原件-----
> > 发件人: Flavio Leitner [mailto:fbl at sysclose.org]
> > 发送时间: 2020年2月4日 5:46
> > 收件人: dev at openvswitch.org
> > 抄送: Stokes Ian <ian.stokes at intel.com>; Loftus Ciara 
> > <ciara.loftus at intel.com>; Ilya Maximets <i.maximets at ovn.org>; Yi 
> > Yang (杨
> > ?D)-云服务集团 <yangyi01 at inspur.com>; txfh2007 <txfh2007 at aliyun.com>; Ben 
> > Pfaff <blp at ovn.org>; Flavio Leitner <fbl at sysclose.org>
> > 主题: [PATCH v2] netdev-linux: Prepend the std packet in the TSO 
> > packet
> > 
> > Usually TSO packets are close to 50k, 60k bytes long, so to to copy 
> > less bytes when receiving a packet from the kernel change the 
> > approach. Instead of extending the MTU sized packet received and 
> > append with remaining TSO data from the TSO buffer, allocate a TSO 
> > packet with enough headroom to prepend the std packet data.
> > 
> > Fixes: 29cf9c1b3b9c ("userspace: Add TCP Segmentation Offload 
> > support")
> > Suggested-by: Ben Pfaff <blp at ovn.org>
> > Signed-off-by: Flavio Leitner <fbl at sysclose.org>
> > ---
> >  lib/dp-packet.c            |   8 +--
> >  lib/dp-packet.h            |   2 +
> >  lib/netdev-linux-private.h |   3 +-
> >  lib/netdev-linux.c         | 117 ++++++++++++++++++++++---------------
> >  4 files changed, 78 insertions(+), 52 deletions(-)
> > 
> > V2:
> >   - tso packets tailroom depends on headroom in netdev_linux_rxq_recv()
> >   - iov_len uses packet's tailroom.
> > 
> >   This patch depends on a previous posted patch to work:
> >   Subject: netdev-linux-private: fix max length to be 16 bits
> >   
> > https://mail.openvswitch.org/pipermail/ovs-dev/2020-February/367469.
> > html
> > 
> >   With both patches applied, I can run iperf3 and scp on both directions
> >   with good performance and no issues.
> > 
> > diff --git a/lib/dp-packet.c b/lib/dp-packet.c index 
> > 8dfedcb7c..cd2623500
> > 100644
> > --- a/lib/dp-packet.c
> > +++ b/lib/dp-packet.c
> > @@ -243,8 +243,8 @@ dp_packet_copy__(struct dp_packet *b, uint8_t 
> > *new_base,
> >  
> >  /* Reallocates 'b' so that it has exactly 'new_headroom' and 'new_tailroom'
> >   * bytes of headroom and tailroom, respectively. */ -static void 
> > -dp_packet_resize__(struct dp_packet *b, size_t new_headroom, size_t
> > new_tailroom)
> > +void
> > +dp_packet_resize(struct dp_packet *b, size_t new_headroom, size_t
> > +new_tailroom)
> >  {
> >      void *new_base, *new_data;
> >      size_t new_allocated;
> > @@ -297,7 +297,7 @@ void
> >  dp_packet_prealloc_tailroom(struct dp_packet *b, size_t size)  {
> >      if (size > dp_packet_tailroom(b)) {
> > -        dp_packet_resize__(b, dp_packet_headroom(b), MAX(size, 64));
> > +        dp_packet_resize(b, dp_packet_headroom(b), MAX(size, 64));
> >      }
> >  }
> >  
> > @@ -308,7 +308,7 @@ void
> >  dp_packet_prealloc_headroom(struct dp_packet *b, size_t size)  {
> >      if (size > dp_packet_headroom(b)) {
> > -        dp_packet_resize__(b, MAX(size, 64), dp_packet_tailroom(b));
> > +        dp_packet_resize(b, MAX(size, 64), dp_packet_tailroom(b));
> >      }
> >  }
> >  
> > diff --git a/lib/dp-packet.h b/lib/dp-packet.h index 
> > 69ae5dfac..9a9d35183
> > 100644
> > --- a/lib/dp-packet.h
> > +++ b/lib/dp-packet.h
> > @@ -152,6 +152,8 @@ struct dp_packet 
> > *dp_packet_clone_with_headroom(const
> > struct dp_packet *,  struct dp_packet *dp_packet_clone_data(const 
> > void *, size_t);  struct dp_packet 
> > *dp_packet_clone_data_with_headroom(const void *, size_t,
> >                                                       size_t 
> > headroom);
> > +void dp_packet_resize(struct dp_packet *b, size_t new_headroom,
> > +                      size_t new_tailroom);
> >  static inline void dp_packet_delete(struct dp_packet *);
> >  
> >  static inline void *dp_packet_at(const struct dp_packet *, size_t 
> > offset, diff --git a/lib/netdev-linux-private.h 
> > b/lib/netdev-linux-private.h index
> > be2d7b10b..c7c515f70 100644
> > --- a/lib/netdev-linux-private.h
> > +++ b/lib/netdev-linux-private.h
> > @@ -45,7 +45,8 @@ struct netdev_rxq_linux {
> >      struct netdev_rxq up;
> >      bool is_tap;
> >      int fd;
> > -    char *aux_bufs[NETDEV_MAX_BURST]; /* Batch of preallocated TSO buffers.
> > */
> > +    struct dp_packet *aux_bufs[NETDEV_MAX_BURST]; /* Preallocated TSO
> > +                                                     packets. */
> >  };
> >  
> >  int netdev_linux_construct(struct netdev *); diff --git a/lib/netdev-linux.
> > c b/lib/netdev-linux.c index 6add3e2fc..c6f3d2740 100644
> > --- a/lib/netdev-linux.c
> > +++ b/lib/netdev-linux.c
> > @@ -1052,15 +1052,6 @@ static struct netdev_rxq *
> >  netdev_linux_rxq_alloc(void)
> >  {
> >      struct netdev_rxq_linux *rx = xzalloc(sizeof *rx);
> > -    if (userspace_tso_enabled()) {
> > -        int i;
> > -
> > -        /* Allocate auxiliay buffers to receive TSO packets. */
> > -        for (i = 0; i < NETDEV_MAX_BURST; i++) {
> > -            rx->aux_bufs[i] = xmalloc(LINUX_RXQ_TSO_MAX_LEN);
> > -        }
> > -    }
> > -
> >      return &rx->up;
> >  }
> >  
> > @@ -1172,7 +1163,7 @@ netdev_linux_rxq_destruct(struct netdev_rxq *rxq_)
> >      }
> >  
> >      for (i = 0; i < NETDEV_MAX_BURST; i++) {
> > -        free(rx->aux_bufs[i]);
> > +        dp_packet_delete(rx->aux_bufs[i]);
> >      }
> >  }
> >  
> > @@ -1238,13 +1229,18 @@ netdev_linux_batch_rxq_recv_sock(struct
> > netdev_rxq_linux *rx, int mtu,
> >          virtio_net_hdr_size = 0;
> >      }
> >  
> > -    std_len = VLAN_ETH_HEADER_LEN + mtu + virtio_net_hdr_size;
> > +    /* The length here needs to be accounted in the same way when the
> > +     * aux_buf is allocated so that it can be prepended to TSO buffer. */
> > +    std_len = virtio_net_hdr_size + VLAN_ETH_HEADER_LEN + mtu;
> >      for (i = 0; i < NETDEV_MAX_BURST; i++) {
> >           buffers[i] = dp_packet_new_with_headroom(std_len,
> > DP_NETDEV_HEADROOM);
> >           iovs[i][IOV_PACKET].iov_base = dp_packet_data(buffers[i]);
> >           iovs[i][IOV_PACKET].iov_len = std_len;
> > -         iovs[i][IOV_AUXBUF].iov_base = rx->aux_bufs[i];
> > -         iovs[i][IOV_AUXBUF].iov_len = LINUX_RXQ_TSO_MAX_LEN;
> > +         if (iovlen == IOV_TSO_SIZE) {
> > +             iovs[i][IOV_AUXBUF].iov_base =
> > dp_packet_data(rx->aux_bufs[i]);
> > +             iovs[i][IOV_AUXBUF].iov_len =
> > dp_packet_tailroom(rx->aux_bufs[i]);
> > +         }
> > +
> >           mmsgs[i].msg_hdr.msg_name = NULL;
> >           mmsgs[i].msg_hdr.msg_namelen = 0;
> >           mmsgs[i].msg_hdr.msg_iov = iovs[i]; @@ -1268,6 +1264,8 @@ 
> > netdev_linux_batch_rxq_recv_sock(struct netdev_rxq_linux *rx, int mtu,
> >      }
> >  
> >      for (i = 0; i < retval; i++) {
> > +        struct dp_packet *pkt;
> > +
> >          if (mmsgs[i].msg_len < ETH_HEADER_LEN) {
> >              struct netdev *netdev_ = netdev_rxq_get_netdev(&rx->up);
> >              struct netdev_linux *netdev = 
> > netdev_linux_cast(netdev_); @@
> > -1280,29 +1278,29 @@ netdev_linux_batch_rxq_recv_sock(struct
> > netdev_rxq_linux *rx, int mtu,
> >          }
> >  
> >          if (mmsgs[i].msg_len > std_len) {
> > -            /* Build a single linear TSO packet by expanding the current
> > packet
> > -             * to append the data received in the aux_buf. */
> > -            size_t extra_len = mmsgs[i].msg_len - std_len;
> > -
> > -            dp_packet_set_size(buffers[i], dp_packet_size(buffers[i])
> > -                               + std_len);
> > -            dp_packet_prealloc_tailroom(buffers[i], extra_len);
> > -            memcpy(dp_packet_tail(buffers[i]), rx->aux_bufs[i], extra_len);
> > -            dp_packet_set_size(buffers[i], dp_packet_size(buffers[i])
> > -                               + extra_len);
> > -        } else {
> > -            dp_packet_set_size(buffers[i], dp_packet_size(buffers[i])
> > -                               + mmsgs[i].msg_len);
> > -        }
> > +            /* Build a single linear TSO packet by prepending the data from
> > +             * std_len buffer to the aux_buf. */
> > +            pkt = rx->aux_bufs[i];
> > +            dp_packet_set_size(pkt, mmsgs[i].msg_len - std_len);
> > +            dp_packet_push(pkt, dp_packet_data(buffers[i]), std_len);
> > +            /* The headroom should be the same in buffers[i], pkt and
> > +             * DP_NETDEV_HEADROOM. */
> > +            dp_packet_resize(pkt, DP_NETDEV_HEADROOM, 0);
> > +            dp_packet_delete(buffers[i]);
> > +            rx->aux_bufs[i] = NULL;
> > +         } else {
> > +            dp_packet_set_size(buffers[i], mmsgs[i].msg_len);
> > +            pkt = buffers[i];
> > +         }
> >  
> > -        if (virtio_net_hdr_size && netdev_linux_parse_vnet_hdr(buffers[i]))
> > {
> > +        if (virtio_net_hdr_size && 
> > + netdev_linux_parse_vnet_hdr(pkt)) {
> >              struct netdev *netdev_ = netdev_rxq_get_netdev(&rx->up);
> >              struct netdev_linux *netdev = 
> > netdev_linux_cast(netdev_);
> >  
> >              /* Unexpected error situation: the virtio header is not present
> >               * or corrupted. Drop the packet but continue in case next ones
> >               * are correct. */
> > -            dp_packet_delete(buffers[i]);
> > +            dp_packet_delete(pkt);
> >              netdev->rx_dropped += 1;
> >              VLOG_WARN_RL(&rl, "%s: Dropped packet: Invalid virtio 
> > net header",
> >                           netdev_get_name(netdev_)); @@ -1325,16 
> > +1323,16 @@ netdev_linux_batch_rxq_recv_sock(struct netdev_rxq_linux *rx, int mtu,
> >                  struct eth_header *eth;
> >                  bool double_tagged;
> >  
> > -                eth = dp_packet_data(buffers[i]);
> > +                eth = dp_packet_data(pkt);
> >                  double_tagged = eth->eth_type == 
> > htons(ETH_TYPE_VLAN_8021Q);
> >  
> > -                eth_push_vlan(buffers[i],
> > +                eth_push_vlan(pkt,
> >                                auxdata_to_vlan_tpid(aux, double_tagged),
> >                                htons(aux->tp_vlan_tci));
> >                  break;
> >              }
> >          }
> > -        dp_packet_batch_add(batch, buffers[i]);
> > +        dp_packet_batch_add(batch, pkt);
> >      }
> >  
> >      /* Delete unused buffers. */
> > @@ -1354,7 +1352,6 @@ static int
> >  netdev_linux_batch_rxq_recv_tap(struct netdev_rxq_linux *rx, int mtu,
> >                                  struct dp_packet_batch *batch)  {
> > -    struct dp_packet *buffer;
> >      int virtio_net_hdr_size;
> >      ssize_t retval;
> >      size_t std_len;
> > @@ -1372,16 +1369,22 @@ netdev_linux_batch_rxq_recv_tap(struct
> > netdev_rxq_linux *rx, int mtu,
> >          virtio_net_hdr_size = 0;
> >      }
> >  
> > -    std_len = VLAN_ETH_HEADER_LEN + mtu + virtio_net_hdr_size;
> > +    /* The length here needs to be accounted in the same way when the
> > +     * aux_buf is allocated so that it can be prepended to TSO buffer. */
> > +    std_len = virtio_net_hdr_size + VLAN_ETH_HEADER_LEN + mtu;
> >      for (i = 0; i < NETDEV_MAX_BURST; i++) {
> > +        struct dp_packet *buffer;
> > +        struct dp_packet *pkt;
> >          struct iovec iov[IOV_TSO_SIZE];
> >  
> >          /* Assume Ethernet port. No need to set packet_type. */
> >          buffer = dp_packet_new_with_headroom(std_len, DP_NETDEV_HEADROOM);
> >          iov[IOV_PACKET].iov_base = dp_packet_data(buffer);
> >          iov[IOV_PACKET].iov_len = std_len;
> > -        iov[IOV_AUXBUF].iov_base = rx->aux_bufs[i];
> > -        iov[IOV_AUXBUF].iov_len = LINUX_RXQ_TSO_MAX_LEN;
> > +        if (iovlen == IOV_TSO_SIZE) {
> > +            iov[IOV_AUXBUF].iov_base = dp_packet_data(rx->aux_bufs[i]);
> > +            iov[IOV_AUXBUF].iov_len = dp_packet_tailroom(rx->aux_bufs[i]);
> > +        }
> >  
> >          do {
> >              retval = readv(rx->fd, iov, iovlen); @@ -1393,33 
> > +1396,36 @@ netdev_linux_batch_rxq_recv_tap(struct netdev_rxq_linux *rx, int mtu,
> >          }
> >  
> >          if (retval > std_len) {
> > -            /* Build a single linear TSO packet by expanding the current
> > packet
> > -             * to append the data received in the aux_buf. */
> > -            size_t extra_len = retval - std_len;
> > -
> > -            dp_packet_set_size(buffer, dp_packet_size(buffer) + std_len);
> > -            dp_packet_prealloc_tailroom(buffer, extra_len);
> > -            memcpy(dp_packet_tail(buffer), rx->aux_bufs[i], extra_len);
> > -            dp_packet_set_size(buffer, dp_packet_size(buffer) + extra_len);
> > +            /* Build a single linear TSO packet by prepending the data from
> > +             * std_len buffer to the aux_buf. */
> > +            pkt = rx->aux_bufs[i];
> > +            dp_packet_set_size(pkt, retval - std_len);
> > +            dp_packet_push(pkt, dp_packet_data(buffer), std_len);
> > +            /* The headroom should be the same in buffers[i], pkt and
> > +             * DP_NETDEV_HEADROOM. */
> > +            dp_packet_resize(pkt, DP_NETDEV_HEADROOM, 0);
> > +            dp_packet_delete(buffer);
> > +            rx->aux_bufs[i] = NULL;
> >          } else {
> >              dp_packet_set_size(buffer, dp_packet_size(buffer) + 
> > retval);
> > +            pkt = buffer;
> >          }
> >  
> > -        if (virtio_net_hdr_size && netdev_linux_parse_vnet_hdr(buffer)) {
> > +        if (virtio_net_hdr_size && 
> > + netdev_linux_parse_vnet_hdr(pkt)) {
> >              struct netdev *netdev_ = netdev_rxq_get_netdev(&rx->up);
> >              struct netdev_linux *netdev = 
> > netdev_linux_cast(netdev_);
> >  
> >              /* Unexpected error situation: the virtio header is not present
> >               * or corrupted. Drop the packet but continue in case next ones
> >               * are correct. */
> > -            dp_packet_delete(buffer);
> > +            dp_packet_delete(pkt);
> >              netdev->rx_dropped += 1;
> >              VLOG_WARN_RL(&rl, "%s: Dropped packet: Invalid virtio 
> > net header",
> >                           netdev_get_name(netdev_));
> >              continue;
> >          }
> >  
> > -        dp_packet_batch_add(batch, buffer);
> > +        dp_packet_batch_add(batch, pkt);
> >      }
> >  
> >      if ((i == 0) && (retval < 0)) { @@ -1442,6 +1448,23 @@ 
> > netdev_linux_rxq_recv(struct netdev_rxq *rxq_, struct 
> > dp_packet_batch *batch,
> >          mtu = ETH_PAYLOAD_MAX;
> >      }
> >  
> > +    if (userspace_tso_enabled()) {
> > +        /* Allocate TSO packets. The packet has enough headroom to store
> > +         * a full non-TSO packet. When a TSO packet is received, the data
> > +         * from non-TSO buffer (std_len) is prepended to the TSO packet
> > +         * (aux_buf). */
> > +        size_t std_len = sizeof(struct virtio_net_hdr) +
> > VLAN_ETH_HEADER_LEN
> > +                         + DP_NETDEV_HEADROOM + mtu;
> > +        size_t data_len = LINUX_RXQ_TSO_MAX_LEN - std_len;
> > +        for (int i = 0; i < NETDEV_MAX_BURST; i++) {
> > +            if (rx->aux_bufs[i]) {
> > +                continue;
> > +            }
> > +
> > +            rx->aux_bufs[i] = dp_packet_new_with_headroom(data_len,
> > std_len);
> > +        }
> > +    }
> > +
> >      dp_packet_batch_init(batch);
> >      retval = (rx->is_tap
> >                ? netdev_linux_batch_rxq_recv_tap(rx, mtu, batch)
> > --
> > 2.24.1
> > 
> 
> 
> 
> --
> fbl
> _______________________________________________
> dev mailing list
> dev at openvswitch.org
> https://mail.openvswitch.org/mailman/listinfo/ovs-dev

--
fbl


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