netdev-dpdk: add support for jumbo frames

Add support for Jumbo Frames to DPDK-enabled port types, using single-segment-mbufs. Using this approach, the amount of memory allocated to each mbuf to store frame data is increased to a value greater than 1518B (typical Ethernet maximum frame length). The increased space available in the mbuf means that an entire Jumbo Frame of a specific size can be carried in a single mbuf, as opposed to partitioning it across multiple mbuf segments. The amount of space allocated to each mbuf to hold frame data is defined dynamically by the user with ovs-vsctl, via the 'mtu_request' parameter. Signed-off-by: Mark Kavanagh <[email protected]> Signed-off-by: Ilya Maximets <[email protected]> [[email protected] rebased] Signed-off-by: Daniele Di Proietto <[email protected]>
nicboul · Aug 13, 2016 · 0072e93 · 0072e93
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diff --git a/INSTALL.DPDK-ADVANCED.md b/INSTALL.DPDK-ADVANCED.md
@@ -1,5 +1,5 @@
 OVS DPDK ADVANCED INSTALL GUIDE
-=================================
+===============================
 
 ## Contents
 
@@ -13,7 +13,8 @@ OVS DPDK ADVANCED INSTALL GUIDE
 8. [Rate Limiting](#rl)
 9. [Flow Control](#fc)
 10. [Pdump](#pdump)
-11. [Vsperf](#vsperf)
+11. [Jumbo Frames](#jumbo)
+12. [Vsperf](#vsperf)
 
 ## <a name="overview"></a> 1. Overview
 
@@ -981,7 +982,58 @@ tcpdump. Issue the following command to view the contents of 'pkts.pcap':
 A performance decrease is expected when using a monitoring application like
 the DPDK pdump app.
 
-## <a name="vsperf"></a> 11. Vsperf
+## <a name="jumbo"></a> 11. Jumbo Frames
+
+By default, DPDK ports are configured with standard Ethernet MTU (1500B). To
+enable Jumbo Frames support for a DPDK port, change the Interface's `mtu_request`
+attribute to a sufficiently large value.
+
+e.g. Add a DPDK Phy port with MTU of 9000:
+
+`ovs-vsctl add-port br0 dpdk0 -- set Interface dpdk0 type=dpdk -- set Interface dpdk0 mtu_request=9000`
+
+e.g. Change the MTU of an existing port to 6200:
+
+`ovs-vsctl set Interface dpdk0 mtu_request=6200`
+
+When Jumbo Frames are enabled, the size of a DPDK port's mbuf segments are
+increased, such that a full Jumbo Frame of a specific size may be accommodated
+within a single mbuf segment.
+
+Jumbo frame support has been validated against 9728B frames (largest frame size
+supported by Fortville NIC), using the DPDK `i40e` driver, but larger frames
+(particularly in use cases involving East-West traffic only), and other DPDK NIC
+drivers may be supported.
+
+### 9.1 vHost Ports and Jumbo Frames
+
+Some additional configuration is needed to take advantage of jumbo frames with
+vhost ports:
+
+    1. `mergeable buffers` must be enabled for vHost ports, as demonstrated in
+        the QEMU command line snippet below:
+
+        ```
+        '-netdev type=vhost-user,id=mynet1,chardev=char0,vhostforce \'
+        '-device virtio-net-pci,mac=00:00:00:00:00:01,netdev=mynet1,mrg_rxbuf=on'
+        ```
+
+    2. Where virtio devices are bound to the Linux kernel driver in a guest
+       environment (i.e. interfaces are not bound to an in-guest DPDK driver),
+       the MTU of those logical network interfaces must also be increased to a
+       sufficiently large value. This avoids segmentation of Jumbo Frames
+       received in the guest. Note that 'MTU' refers to the length of the IP
+       packet only, and not that of the entire frame.
+
+       To calculate the exact MTU of a standard IPv4 frame, subtract the L2
+       header and CRC lengths (i.e. 18B) from the max supported frame size.
+       So, to set the MTU for a 9018B Jumbo Frame:
+
+       ```
+       ifconfig eth1 mtu 9000
+       ```
+
+## <a name="vsperf"></a> 12. Vsperf
 
 Vsperf project goal is to develop vSwitch test framework that can be used to
 validate the suitability of different vSwitch implementations in a Telco deployment

diff --git a/INSTALL.DPDK.md b/INSTALL.DPDK.md
@@ -590,7 +590,6 @@ can be found in [Vhost Walkthrough].
 
 ## <a name="ovslimits"></a> 6. Limitations
 
-  - Supports MTU size 1500, MTU setting for DPDK netdevs will be in future OVS release.
   - Currently DPDK ports does not use HW offload functionality.
   - Network Interface Firmware requirements:
     Each release of DPDK is validated against a specific firmware version for

diff --git a/NEWS b/NEWS
@@ -70,6 +70,7 @@ Post-v2.5.0
        fragmentation or NAT support yet)
      * Support for DPDK 16.07
      * Optional support for DPDK pdump enabled.
+     * Jumbo frame support
    - Increase number of registers to 16.
    - ovs-benchmark: This utility has been removed due to lack of use and
      bitrot.

diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
@@ -84,6 +84,7 @@ static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
                                     + sizeof(struct dp_packet)    \
                                     + RTE_PKTMBUF_HEADROOM)
 #define NETDEV_DPDK_MBUF_ALIGN      1024
+#define NETDEV_DPDK_MAX_PKT_LEN     9728
 
 /* Max and min number of packets in the mempool.  OVS tries to allocate a
  * mempool with MAX_NB_MBUF: if this fails (because the system doesn't have
@@ -373,6 +374,7 @@ struct netdev_dpdk {
     /* The following properties cannot be changed when a device is running,
      * so we remember the request and update them next time
      * netdev_dpdk*_reconfigure() is called */
+    int requested_mtu;
     int requested_n_txq;
     int requested_n_rxq;
 
@@ -482,10 +484,19 @@ dpdk_mp_get(int socket_id, int mtu) OVS_REQUIRES(dpdk_mutex)
     dmp->mtu = mtu;
     dmp->refcount = 1;
     mbp_priv.mbuf_data_room_size = MBUF_SIZE(mtu) - sizeof(struct dp_packet);
-    mbp_priv.mbuf_priv_size = sizeof (struct dp_packet) -
-                              sizeof (struct rte_mbuf);
+    mbp_priv.mbuf_priv_size = sizeof (struct dp_packet)
+                              - sizeof (struct rte_mbuf);
+    /* XXX: this is a really rough method of provisioning memory.
+     * It's impossible to determine what the exact memory requirements are when
+     * the number of ports and rxqs that utilize a particular mempool can change
+     * dynamically at runtime. For the moment, use this rough heurisitic.
+     */
+    if (mtu >= ETHER_MTU) {
+        mp_size = MAX_NB_MBUF;
+    } else {
+        mp_size = MIN_NB_MBUF;
+    }
 
-    mp_size = MAX_NB_MBUF;
     do {
         if (snprintf(mp_name, RTE_MEMPOOL_NAMESIZE, "ovs_mp_%d_%d_%u",
                      dmp->mtu, dmp->socket_id, mp_size) < 0) {
@@ -525,6 +536,35 @@ dpdk_mp_put(struct dpdk_mp *dmp) OVS_REQUIRES(dpdk_mutex)
     }
 }
 
+/* Tries to allocate new mempool on requested_socket_id with
+ * mbuf size corresponding to requested_mtu.
+ * On success new configuration will be applied.
+ * On error, device will be left unchanged. */
+static int
+netdev_dpdk_mempool_configure(struct netdev_dpdk *dev)
+    OVS_REQUIRES(dpdk_mutex)
+    OVS_REQUIRES(dev->mutex)
+{
+    uint32_t buf_size = dpdk_buf_size(dev->requested_mtu);
+    struct dpdk_mp *mp;
+
+    mp = dpdk_mp_get(dev->requested_socket_id, FRAME_LEN_TO_MTU(buf_size));
+    if (!mp) {
+        VLOG_ERR("Insufficient memory to create memory pool for netdev "
+                 "%s, with MTU %d on socket %d\n",
+                 dev->up.name, dev->requested_mtu, dev->requested_socket_id);
+        return ENOMEM;
+    } else {
+        dpdk_mp_put(dev->dpdk_mp);
+        dev->dpdk_mp = mp;
+        dev->mtu = dev->requested_mtu;
+        dev->socket_id = dev->requested_socket_id;
+        dev->max_packet_len = MTU_TO_FRAME_LEN(dev->mtu);
+    }
+
+    return 0;
+}
+
 static void
 check_link_status(struct netdev_dpdk *dev)
 {
@@ -576,7 +616,15 @@ dpdk_eth_dev_queue_setup(struct netdev_dpdk *dev, int n_rxq, int n_txq)
 {
     int diag = 0;
     int i;
+    struct rte_eth_conf conf = port_conf;
 
+    if (dev->mtu > ETHER_MTU) {
+        conf.rxmode.jumbo_frame = 1;
+        conf.rxmode.max_rx_pkt_len = dev->max_packet_len;
+    } else {
+        conf.rxmode.jumbo_frame = 0;
+        conf.rxmode.max_rx_pkt_len = 0;
+    }
     /* A device may report more queues than it makes available (this has
      * been observed for Intel xl710, which reserves some of them for
      * SRIOV):  rte_eth_*_queue_setup will fail if a queue is not
@@ -587,8 +635,10 @@ dpdk_eth_dev_queue_setup(struct netdev_dpdk *dev, int n_rxq, int n_txq)
             VLOG_INFO("Retrying setup with (rxq:%d txq:%d)", n_rxq, n_txq);
         }
 
-        diag = rte_eth_dev_configure(dev->port_id, n_rxq, n_txq, &port_conf);
+        diag = rte_eth_dev_configure(dev->port_id, n_rxq, n_txq, &conf);
         if (diag) {
+            VLOG_WARN("Interface %s eth_dev setup error %s\n",
+                      dev->up.name, rte_strerror(-diag));
             break;
         }
 
@@ -741,7 +791,6 @@ netdev_dpdk_init(struct netdev *netdev, unsigned int port_no,
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
     int sid;
     int err = 0;
-    uint32_t buf_size;
 
     ovs_mutex_init(&dev->mutex);
     ovs_mutex_lock(&dev->mutex);
@@ -762,15 +811,13 @@ netdev_dpdk_init(struct netdev *netdev, unsigned int port_no,
     dev->port_id = port_no;
     dev->type = type;
     dev->flags = 0;
-    dev->mtu = ETHER_MTU;
+    dev->requested_mtu = dev->mtu = ETHER_MTU;
     dev->max_packet_len = MTU_TO_FRAME_LEN(dev->mtu);
     ovsrcu_index_init(&dev->vid, -1);
     dev->vhost_reconfigured = false;
 
-    buf_size = dpdk_buf_size(dev->mtu);
-    dev->dpdk_mp = dpdk_mp_get(dev->socket_id, FRAME_LEN_TO_MTU(buf_size));
-    if (!dev->dpdk_mp) {
-        err = ENOMEM;
+    err = netdev_dpdk_mempool_configure(dev);
+    if (err) {
         goto unlock;
     }
 
@@ -1008,6 +1055,7 @@ netdev_dpdk_get_config(const struct netdev *netdev, struct smap *args)
     smap_add_format(args, "configured_rx_queues", "%d", netdev->n_rxq);
     smap_add_format(args, "requested_tx_queues", "%d", dev->requested_n_txq);
     smap_add_format(args, "configured_tx_queues", "%d", netdev->n_txq);
+    smap_add_format(args, "mtu", "%d", dev->mtu);
     ovs_mutex_unlock(&dev->mutex);
 
     return 0;
@@ -1382,6 +1430,7 @@ __netdev_dpdk_vhost_send(struct netdev *netdev, int qid,
     struct rte_mbuf **cur_pkts = (struct rte_mbuf **) pkts;
     unsigned int total_pkts = cnt;
     unsigned int qos_pkts = 0;
+    unsigned int mtu_dropped = 0;
     int i, retries = 0;
 
     qid = dev->tx_q[qid % netdev->n_txq].map;
@@ -1403,25 +1452,41 @@ __netdev_dpdk_vhost_send(struct netdev *netdev, int qid,
     do {
         int vhost_qid = qid * VIRTIO_QNUM + VIRTIO_RXQ;
         unsigned int tx_pkts;
+        unsigned int try_tx_pkts = cnt;
 
+        for (i = 0; i < cnt; i++) {
+            if (cur_pkts[i]->pkt_len > dev->max_packet_len) {
+                try_tx_pkts = i;
+                break;
+            }
+        }
+        if (!try_tx_pkts) {
+            cur_pkts++;
+            mtu_dropped++;
+            cnt--;
+            continue;
+        }
         tx_pkts = rte_vhost_enqueue_burst(netdev_dpdk_get_vid(dev),
-                                          vhost_qid, cur_pkts, cnt);
+                                          vhost_qid, cur_pkts, try_tx_pkts);
         if (OVS_LIKELY(tx_pkts)) {
             /* Packets have been sent.*/
             cnt -= tx_pkts;
             /* Prepare for possible retry.*/
             cur_pkts = &cur_pkts[tx_pkts];
+            if (tx_pkts != try_tx_pkts) {
+                retries++;
+            }
         } else {
             /* No packets sent - do not retry.*/
             break;
         }
-    } while (cnt && (retries++ < VHOST_ENQ_RETRY_NUM));
+    } while (cnt && (retries <= VHOST_ENQ_RETRY_NUM));
 
     rte_spinlock_unlock(&dev->tx_q[qid].tx_lock);
 
     rte_spinlock_lock(&dev->stats_lock);
-    cnt += qos_pkts;
-    netdev_dpdk_vhost_update_tx_counters(&dev->stats, pkts, total_pkts, cnt);
+    netdev_dpdk_vhost_update_tx_counters(&dev->stats, pkts, total_pkts,
+                                         cnt + mtu_dropped + qos_pkts);
     rte_spinlock_unlock(&dev->stats_lock);
 
 out:
@@ -1649,6 +1714,27 @@ netdev_dpdk_get_mtu(const struct netdev *netdev, int *mtup)
     return 0;
 }
 
+static int
+netdev_dpdk_set_mtu(struct netdev *netdev, int mtu)
+{
+    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
+
+    if (MTU_TO_FRAME_LEN(mtu) > NETDEV_DPDK_MAX_PKT_LEN
+        || mtu < ETHER_MIN_MTU) {
+        VLOG_WARN("%s: unsupported MTU %d\n", dev->up.name, mtu);
+        return EINVAL;
+    }
+
+    ovs_mutex_lock(&dev->mutex);
+    if (dev->requested_mtu != mtu) {
+        dev->requested_mtu = mtu;
+        netdev_request_reconfigure(netdev);
+    }
+    ovs_mutex_unlock(&dev->mutex);
+
+    return 0;
+}
+
 static int
 netdev_dpdk_get_carrier(const struct netdev *netdev, bool *carrier);
 
@@ -2834,21 +2920,28 @@ netdev_dpdk_reconfigure(struct netdev *netdev)
     ovs_mutex_lock(&dev->mutex);
 
     if (netdev->n_txq == dev->requested_n_txq
-        && netdev->n_rxq == dev->requested_n_rxq) {
+        && netdev->n_rxq == dev->requested_n_rxq
+        && dev->mtu == dev->requested_mtu) {
         /* Reconfiguration is unnecessary */
 
         goto out;
     }
 
     rte_eth_dev_stop(dev->port_id);
 
+    if (dev->mtu != dev->requested_mtu) {
+        netdev_dpdk_mempool_configure(dev);
+    }
+
     netdev->n_txq = dev->requested_n_txq;
     netdev->n_rxq = dev->requested_n_rxq;
 
     rte_free(dev->tx_q);
     err = dpdk_eth_dev_init(dev);
     netdev_dpdk_alloc_txq(dev, netdev->n_txq);
 
+    netdev_change_seq_changed(netdev);
+
 out:
 
     ovs_mutex_unlock(&dev->mutex);
@@ -2861,7 +2954,6 @@ static int
 netdev_dpdk_vhost_user_reconfigure(struct netdev *netdev)
 {
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
-    int err = 0;
 
     ovs_mutex_lock(&dpdk_mutex);
     ovs_mutex_lock(&dev->mutex);
@@ -2876,13 +2968,10 @@ netdev_dpdk_vhost_user_reconfigure(struct netdev *netdev)
 
     netdev_dpdk_remap_txqs(dev);
 
-    if (dev->requested_socket_id != dev->socket_id) {
-        dev->socket_id = dev->requested_socket_id;
-        /* Change mempool to new NUMA Node */
-        dpdk_mp_put(dev->dpdk_mp);
-        dev->dpdk_mp = dpdk_mp_get(dev->socket_id, dev->mtu);
-        if (!dev->dpdk_mp) {
-            err = ENOMEM;
+    if (dev->requested_socket_id != dev->socket_id
+        || dev->requested_mtu != dev->mtu) {
+        if (!netdev_dpdk_mempool_configure(dev)) {
+            netdev_change_seq_changed(netdev);
         }
     }
 
@@ -2893,7 +2982,7 @@ netdev_dpdk_vhost_user_reconfigure(struct netdev *netdev)
     ovs_mutex_unlock(&dev->mutex);
     ovs_mutex_unlock(&dpdk_mutex);
 
-    return err;
+    return 0;
 }
 
 static int
@@ -2907,6 +2996,12 @@ netdev_dpdk_vhost_cuse_reconfigure(struct netdev *netdev)
     netdev->n_txq = dev->requested_n_txq;
     netdev->n_rxq = 1;
 
+    if (dev->requested_mtu != dev->mtu) {
+        if (!netdev_dpdk_mempool_configure(dev)) {
+            netdev_change_seq_changed(netdev);
+        }
+    }
+
     ovs_mutex_unlock(&dev->mutex);
     ovs_mutex_unlock(&dpdk_mutex);
 
@@ -2944,7 +3039,7 @@ netdev_dpdk_vhost_cuse_reconfigure(struct netdev *netdev)
     netdev_dpdk_set_etheraddr,                                \
     netdev_dpdk_get_etheraddr,                                \
     netdev_dpdk_get_mtu,                                      \
-    NULL,                       /* set_mtu */                 \
+    netdev_dpdk_set_mtu,                                      \
     netdev_dpdk_get_ifindex,                                  \
     GET_CARRIER,                                              \
     netdev_dpdk_get_carrier_resets,                           \