[ovs-dev] [PATCH v9 15/15] netdev-dpdk: Use ->reconfigure() call to change rx/tx queues.

Ilya Maximets i.maximets at samsung.com
Mon May 16 06:22:06 UTC 2016


One typo inline.

Best regards, Ilya Maximets.

On 23.04.2016 04:03, Daniele Di Proietto wrote:
> This introduces in dpif-netdev and netdev-dpdk the first use for the
> newly introduce reconfigure netdev call.
> 
> When a request to change the number of queues comes, netdev-dpdk will
> remember this and notify the upper layer via
> netdev_request_reconfigure().
> 
> The datapath, instead of periodically calling netdev_set_multiq(), can
> detect this and call reconfigure().
> 
> This mechanism can also be used to:
> * Automatically match the number of rxq with the one provided by qemu
>   via the new_device callback.
> * Provide a way to change the MTU of dpdk devices at runtime.
> * Move a DPDK vhost device to the proper NUMA socket.
> 
> Signed-off-by: Daniele Di Proietto <diproiettod at vmware.com>
> ---
>  lib/dpif-netdev.c     |  69 +++++++++---------
>  lib/netdev-bsd.c      |   2 +-
>  lib/netdev-dpdk.c     | 195 ++++++++++++++++++++++++++------------------------
>  lib/netdev-dummy.c    |   2 +-
>  lib/netdev-linux.c    |   2 +-
>  lib/netdev-provider.h |  23 +++---
>  lib/netdev-vport.c    |   2 +-
>  lib/netdev.c          |  36 +++-------
>  lib/netdev.h          |   3 +-
>  9 files changed, 160 insertions(+), 174 deletions(-)
> 
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index 7531c2f..a1fa2d7 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -257,8 +257,6 @@ struct dp_netdev_port {
>      unsigned n_rxq;             /* Number of elements in 'rxq' */
>      struct netdev_rxq **rxq;
>      char *type;                 /* Port type as requested by user. */
> -    int latest_requested_n_rxq; /* Latest requested from netdev number
> -                                   of rx queues. */
>  };
>  
>  /* Contained by struct dp_netdev_flow's 'stats' member.  */
> @@ -1166,20 +1164,26 @@ port_create(const char *devname, const char *open_type, const char *type,
>          /* There can only be ovs_numa_get_n_cores() pmd threads,
>           * so creates a txq for each, and one extra for the non
>           * pmd threads. */
> -        error = netdev_set_multiq(netdev, n_cores + 1,
> -                                  netdev_requested_n_rxq(netdev));
> +        error = netdev_set_tx_multiq(netdev, n_cores + 1);
>          if (error && (error != EOPNOTSUPP)) {
>              VLOG_ERR("%s, cannot set multiq", devname);
>              goto out;
>          }
>      }
> +
> +    if (netdev_is_reconf_required(netdev)) {
> +        error = netdev_reconfigure(netdev);
> +        if (error) {
> +            goto out;
> +        }
> +    }
> +
>      port = xzalloc(sizeof *port);
>      port->port_no = port_no;
>      port->netdev = netdev;
>      port->n_rxq = netdev_n_rxq(netdev);
>      port->rxq = xcalloc(port->n_rxq, sizeof *port->rxq);
>      port->type = xstrdup(type);
> -    port->latest_requested_n_rxq = netdev_requested_n_rxq(netdev);
>  
>      for (i = 0; i < port->n_rxq; i++) {
>          error = netdev_rxq_open(netdev, &port->rxq[i], i);
> @@ -2467,27 +2471,6 @@ dpif_netdev_operate(struct dpif *dpif, struct dpif_op **ops, size_t n_ops)
>      }
>  }
>  
> -/* Returns true if the configuration for rx queues is changed. */
> -static bool
> -pmd_n_rxq_changed(const struct dp_netdev *dp)
> -{
> -    struct dp_netdev_port *port;
> -
> -    ovs_mutex_lock(&dp->port_mutex);
> -    HMAP_FOR_EACH (port, node, &dp->ports) {
> -        int requested_n_rxq = netdev_requested_n_rxq(port->netdev);
> -
> -        if (netdev_is_pmd(port->netdev)
> -            && port->latest_requested_n_rxq != requested_n_rxq) {
> -            ovs_mutex_unlock(&dp->port_mutex);
> -            return true;
> -        }
> -    }
> -    ovs_mutex_unlock(&dp->port_mutex);
> -
> -    return false;
> -}
> -
>  static bool
>  cmask_equals(const char *a, const char *b)
>  {
> @@ -2611,11 +2594,9 @@ static int
>  port_reconfigure(struct dp_netdev_port *port)
>  {
>      struct netdev *netdev = port->netdev;
> -    int requested_n_rxq = netdev_requested_n_rxq(netdev);
>      int i, err;
>  
> -    if (!netdev_is_pmd(port->netdev)
> -        || port->latest_requested_n_rxq != requested_n_rxq) {
> +    if (!netdev_is_reconf_required(netdev)) {
>          return 0;
>      }
>  
> @@ -2626,15 +2607,14 @@ port_reconfigure(struct dp_netdev_port *port)
>      }
>      port->n_rxq = 0;
>  
> -    /* Sets the new rx queue config. */
> -    err = netdev_set_multiq(port->netdev, ovs_numa_get_n_cores() + 1,
> -                            requested_n_rxq);
> +    /* Allows 'netdev' to apply the pending configuration changes. */
> +    err = netdev_reconfigure(netdev);
>      if (err && (err != EOPNOTSUPP)) {
> -        VLOG_ERR("Failed to set dpdk interface %s rx_queue to: %u",
> -                 netdev_get_name(port->netdev), requested_n_rxq);
> +        VLOG_ERR("Failed to set interface %s new configuration",
> +                 netdev_get_name(netdev));
>          return err;
>      }
> -    /* If the set_multiq() above succeeds, reopens the 'rxq's. */
> +    /* If the netdev_reconfigure( above succeeds, reopens the 'rxq's. */

Forgotten ')'.

>      port->rxq = xrealloc(port->rxq, sizeof *port->rxq * netdev_n_rxq(netdev));
>      for (i = 0; i < netdev_n_rxq(netdev); i++) {
>          err = netdev_rxq_open(netdev, &port->rxq[i], i);
> @@ -2678,6 +2658,22 @@ reconfigure_pmd_threads(struct dp_netdev *dp)
>      dp_netdev_reset_pmd_threads(dp);
>  }
>  
> +/* Returns true if one of the netdevs in 'dp' requires a reconfiguration */
> +static bool
> +ports_require_restart(const struct dp_netdev *dp)
> +    OVS_REQUIRES(dp->port_mutex)
> +{
> +    struct dp_netdev_port *port;
> +
> +    HMAP_FOR_EACH (port, node, &dp->ports) {
> +        if (netdev_is_reconf_required(port->netdev)) {
> +            return true;
> +        }
> +    }
> +
> +    return false;
> +}
> +
>  /* Return true if needs to revalidate datapath flows. */
>  static bool
>  dpif_netdev_run(struct dpif *dpif)
> @@ -2704,7 +2700,7 @@ dpif_netdev_run(struct dpif *dpif)
>      dp_netdev_pmd_unref(non_pmd);
>  
>      if (!cmask_equals(dp->pmd_cmask, dp->requested_pmd_cmask)
> -        || pmd_n_rxq_changed(dp)) {
> +        || ports_require_restart(dp)) {
>          reconfigure_pmd_threads(dp);
>      }
>      ovs_mutex_unlock(&dp->port_mutex);
> @@ -2729,6 +2725,7 @@ dpif_netdev_wait(struct dpif *dpif)
>      ovs_mutex_lock(&dp_netdev_mutex);
>      ovs_mutex_lock(&dp->port_mutex);
>      HMAP_FOR_EACH (port, node, &dp->ports) {
> +        netdev_wait_reconf_required(port->netdev);
>          if (!netdev_is_pmd(port->netdev)) {
>              int i;
>  
> diff --git a/lib/netdev-bsd.c b/lib/netdev-bsd.c
> index 32e8f74..43fa982 100644
> --- a/lib/netdev-bsd.c
> +++ b/lib/netdev-bsd.c
> @@ -1497,7 +1497,7 @@ netdev_bsd_update_flags(struct netdev *netdev_, enum netdev_flags off,
>      NULL, /* push header */                          \
>      NULL, /* pop header */                           \
>      NULL, /* get_numa_id */                          \
> -    NULL, /* set_multiq */                           \
> +    NULL, /* set_tx_multiq */                        \
>                                                       \
>      netdev_bsd_send,                                 \
>      netdev_bsd_send_wait,                            \
> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> index c4ff039..d4e8bf0 100644
> --- a/lib/netdev-dpdk.c
> +++ b/lib/netdev-dpdk.c
> @@ -342,6 +342,11 @@ struct netdev_dpdk {
>      struct qos_conf *qos_conf;
>      rte_spinlock_t qos_lock;
>  
> +    /* 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_n_txq;
> +    int requested_n_rxq;
>  };
>  
>  struct netdev_rxq_dpdk {
> @@ -723,7 +728,8 @@ netdev_dpdk_init(struct netdev *netdev, unsigned int port_no,
>  
>      netdev->n_txq = NR_QUEUE;
>      netdev->n_rxq = NR_QUEUE;
> -    netdev->requested_n_rxq = NR_QUEUE;
> +    dev->requested_n_rxq = NR_QUEUE;
> +    dev->requested_n_txq = NR_QUEUE;
>      dev->real_n_txq = NR_QUEUE;
>  
>      if (type == DPDK_DEV_ETH) {
> @@ -909,7 +915,7 @@ netdev_dpdk_get_config(const struct netdev *netdev, struct smap *args)
>  
>      ovs_mutex_lock(&dev->mutex);
>  
> -    smap_add_format(args, "requested_rx_queues", "%d", netdev->requested_n_rxq);
> +    smap_add_format(args, "requested_rx_queues", "%d", dev->requested_n_rxq);
>      smap_add_format(args, "configured_rx_queues", "%d", netdev->n_rxq);
>      smap_add_format(args, "requested_tx_queues", "%d", netdev->n_txq);
>      smap_add_format(args, "configured_tx_queues", "%d", dev->real_n_txq);
> @@ -922,11 +928,14 @@ static int
>  netdev_dpdk_set_config(struct netdev *netdev, const struct smap *args)
>  {
>      struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
> +    int new_n_rxq;
>  
>      ovs_mutex_lock(&dev->mutex);
> -    netdev->requested_n_rxq = MAX(smap_get_int(args, "n_rxq",
> -                                               netdev->requested_n_rxq), 1);
> -    netdev_change_seq_changed(netdev);
> +    new_n_rxq = MAX(smap_get_int(args, "n_rxq", dev->requested_n_rxq), 1);
> +    if (new_n_rxq != dev->requested_n_rxq) {
> +        dev->requested_n_rxq = new_n_rxq;
> +        netdev_request_reconfigure(netdev);
> +    }
>      ovs_mutex_unlock(&dev->mutex);
>  
>      return 0;
> @@ -940,95 +949,24 @@ netdev_dpdk_get_numa_id(const struct netdev *netdev)
>      return dev->socket_id;
>  }
>  
> -/* Sets the number of tx queues and rx queues for the dpdk interface.
> - * If the configuration fails, do not try restoring its old configuration
> - * and just returns the error. */
> +/* Sets the number of tx queues for the dpdk interface. */
>  static int
> -netdev_dpdk_set_multiq(struct netdev *netdev, unsigned int n_txq,
> -                       unsigned int n_rxq)
> +netdev_dpdk_set_tx_multiq(struct netdev *netdev, unsigned int n_txq)
>  {
>      struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
> -    int err = 0;
> -    int old_rxq, old_txq;
> -
> -    if (netdev->n_txq == n_txq && netdev->n_rxq == n_rxq) {
> -        return err;
> -    }
>  
> -    ovs_mutex_lock(&dpdk_mutex);
>      ovs_mutex_lock(&dev->mutex);
>  
> -    rte_eth_dev_stop(dev->port_id);
> -
> -    old_txq = netdev->n_txq;
> -    old_rxq = netdev->n_rxq;
> -    netdev->n_txq = n_txq;
> -    netdev->n_rxq = n_rxq;
> -
> -    rte_free(dev->tx_q);
> -    err = dpdk_eth_dev_init(dev);
> -    netdev_dpdk_alloc_txq(dev, dev->real_n_txq);
> -    if (err) {
> -        /* If there has been an error, it means that the requested queues
> -         * have not been created.  Restore the old numbers. */
> -        netdev->n_txq = old_txq;
> -        netdev->n_rxq = old_rxq;
> -    }
> -
> -    dev->txq_needs_locking = dev->real_n_txq != netdev->n_txq;
> -
> -    ovs_mutex_unlock(&dev->mutex);
> -    ovs_mutex_unlock(&dpdk_mutex);
> -
> -    return err;
> -}
> -
> -static int
> -netdev_dpdk_vhost_cuse_set_multiq(struct netdev *netdev, unsigned int n_txq,
> -                                  unsigned int n_rxq)
> -{
> -    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
> -    int err = 0;
> -
> -    if (netdev->n_txq == n_txq && netdev->n_rxq == n_rxq) {
> -        return err;
> -    }
> -
> -    ovs_mutex_lock(&dpdk_mutex);
> -    ovs_mutex_lock(&dev->mutex);
> -
> -    netdev->n_txq = n_txq;
> -    dev->real_n_txq = 1;
> -    netdev->n_rxq = 1;
> -    dev->txq_needs_locking = dev->real_n_txq != netdev->n_txq;
> -
> -    ovs_mutex_unlock(&dev->mutex);
> -    ovs_mutex_unlock(&dpdk_mutex);
> -
> -    return err;
> -}
> -
> -static int
> -netdev_dpdk_vhost_set_multiq(struct netdev *netdev, unsigned int n_txq,
> -                             unsigned int n_rxq)
> -{
> -    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
> -    int err = 0;
> -
> -    if (netdev->n_txq == n_txq && netdev->n_rxq == n_rxq) {
> -        return err;
> +    if (dev->requested_n_txq == n_txq) {
> +        goto out;
>      }
>  
> -    ovs_mutex_lock(&dpdk_mutex);
> -    ovs_mutex_lock(&dev->mutex);
> -
> -    netdev->n_txq = n_txq;
> -    netdev->n_rxq = n_rxq;
> +    dev->requested_n_txq = n_txq;
> +    netdev_request_reconfigure(netdev);
>  
> +out:
>      ovs_mutex_unlock(&dev->mutex);
> -    ovs_mutex_unlock(&dpdk_mutex);
> -
> -    return err;
> +    return 0;
>  }
>  
>  static struct netdev_rxq *
> @@ -2592,6 +2530,7 @@ egress_policer_qos_get(const struct netdev *netdev, struct smap *details)
>                      1ULL * policer->app_srtcm_params.cir);
>      smap_add_format(details, "cbs", "%llu",
>                      1ULL * policer->app_srtcm_params.cbs);
> +
>      return 0;
>  }
>  
> @@ -2661,8 +2600,80 @@ static const struct dpdk_qos_ops egress_policer_ops = {
>      egress_policer_run
>  };
>  
> -#define NETDEV_DPDK_CLASS(NAME, INIT, CONSTRUCT, DESTRUCT, MULTIQ, SEND, \
> -    GET_CARRIER, GET_STATS, GET_FEATURES, GET_STATUS, RXQ_RECV)          \
> +static int
> +netdev_dpdk_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);
> +
> +    if (netdev->n_txq == dev->requested_n_txq
> +        && netdev->n_rxq == dev->requested_n_rxq) {
> +        /* Reconfiguration is unnecessary */
> +
> +        goto out;
> +    }
> +
> +    rte_eth_dev_stop(dev->port_id);
> +
> +    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, dev->real_n_txq);
> +
> +    dev->txq_needs_locking = dev->real_n_txq != netdev->n_txq;
> +
> +out:
> +
> +    ovs_mutex_unlock(&dev->mutex);
> +    ovs_mutex_unlock(&dpdk_mutex);
> +
> +    return err;
> +}
> +
> +static int
> +netdev_dpdk_vhost_user_reconfigure(struct netdev *netdev)
> +{
> +    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
> +
> +    ovs_mutex_lock(&dpdk_mutex);
> +    ovs_mutex_lock(&dev->mutex);
> +
> +    netdev->n_txq = dev->requested_n_txq;
> +    netdev->n_rxq = dev->requested_n_rxq;
> +
> +    ovs_mutex_unlock(&dev->mutex);
> +    ovs_mutex_unlock(&dpdk_mutex);
> +
> +    return 0;
> +}
> +
> +static int
> +netdev_dpdk_vhost_cuse_reconfigure(struct netdev *netdev)
> +{
> +    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
> +
> +    ovs_mutex_lock(&dpdk_mutex);
> +    ovs_mutex_lock(&dev->mutex);
> +
> +    netdev->n_txq = dev->requested_n_txq;
> +    dev->real_n_txq = 1;
> +    netdev->n_rxq = 1;
> +    dev->txq_needs_locking = dev->real_n_txq != netdev->n_txq;
> +
> +    ovs_mutex_unlock(&dev->mutex);
> +    ovs_mutex_unlock(&dpdk_mutex);
> +
> +    return 0;
> +}
> +
> +#define NETDEV_DPDK_CLASS(NAME, INIT, CONSTRUCT, DESTRUCT, SEND, \
> +                          GET_CARRIER, GET_STATS, GET_FEATURES,  \
> +                          GET_STATUS, RECONFIGURE, RXQ_RECV)     \
>  {                                                             \
>      NAME,                                                     \
>      true,                       /* is_pmd */                  \
> @@ -2681,7 +2692,7 @@ static const struct dpdk_qos_ops egress_policer_ops = {
>      NULL,                       /* push header */             \
>      NULL,                       /* pop header */              \
>      netdev_dpdk_get_numa_id,    /* get_numa_id */             \
> -    MULTIQ,                     /* set_multiq */              \
> +    netdev_dpdk_set_tx_multiq,                                \
>                                                                \
>      SEND,                       /* send */                    \
>      NULL,                       /* send_wait */               \
> @@ -2720,7 +2731,7 @@ static const struct dpdk_qos_ops egress_policer_ops = {
>      NULL,                       /* arp_lookup */              \
>                                                                \
>      netdev_dpdk_update_flags,                                 \
> -    NULL,                       /* reconfigure */             \
> +    RECONFIGURE,                                              \
>                                                                \
>      netdev_dpdk_rxq_alloc,                                    \
>      netdev_dpdk_rxq_construct,                                \
> @@ -2835,12 +2846,12 @@ static const struct netdev_class dpdk_class =
>          NULL,
>          netdev_dpdk_construct,
>          netdev_dpdk_destruct,
> -        netdev_dpdk_set_multiq,
>          netdev_dpdk_eth_send,
>          netdev_dpdk_get_carrier,
>          netdev_dpdk_get_stats,
>          netdev_dpdk_get_features,
>          netdev_dpdk_get_status,
> +        netdev_dpdk_reconfigure,
>          netdev_dpdk_rxq_recv);
>  
>  static const struct netdev_class dpdk_ring_class =
> @@ -2849,12 +2860,12 @@ static const struct netdev_class dpdk_ring_class =
>          NULL,
>          netdev_dpdk_ring_construct,
>          netdev_dpdk_destruct,
> -        netdev_dpdk_set_multiq,
>          netdev_dpdk_ring_send,
>          netdev_dpdk_get_carrier,
>          netdev_dpdk_get_stats,
>          netdev_dpdk_get_features,
>          netdev_dpdk_get_status,
> +        netdev_dpdk_reconfigure,
>          netdev_dpdk_rxq_recv);
>  
>  static const struct netdev_class OVS_UNUSED dpdk_vhost_cuse_class =
> @@ -2863,12 +2874,12 @@ static const struct netdev_class OVS_UNUSED dpdk_vhost_cuse_class =
>          dpdk_vhost_cuse_class_init,
>          netdev_dpdk_vhost_cuse_construct,
>          netdev_dpdk_vhost_destruct,
> -        netdev_dpdk_vhost_cuse_set_multiq,
>          netdev_dpdk_vhost_send,
>          netdev_dpdk_vhost_get_carrier,
>          netdev_dpdk_vhost_get_stats,
>          NULL,
>          NULL,
> +        netdev_dpdk_vhost_cuse_reconfigure,
>          netdev_dpdk_vhost_rxq_recv);
>  
>  static const struct netdev_class OVS_UNUSED dpdk_vhost_user_class =
> @@ -2877,12 +2888,12 @@ static const struct netdev_class OVS_UNUSED dpdk_vhost_user_class =
>          dpdk_vhost_user_class_init,
>          netdev_dpdk_vhost_user_construct,
>          netdev_dpdk_vhost_destruct,
> -        netdev_dpdk_vhost_set_multiq,
>          netdev_dpdk_vhost_send,
>          netdev_dpdk_vhost_get_carrier,
>          netdev_dpdk_vhost_get_stats,
>          NULL,
>          NULL,
> +        netdev_dpdk_vhost_user_reconfigure,
>          netdev_dpdk_vhost_rxq_recv);
>  
>  void
> diff --git a/lib/netdev-dummy.c b/lib/netdev-dummy.c
> index a001322..ac3e491 100644
> --- a/lib/netdev-dummy.c
> +++ b/lib/netdev-dummy.c
> @@ -1235,7 +1235,7 @@ static const struct netdev_class dummy_class = {
>      NULL,                       /* push header */
>      NULL,                       /* pop header */
>      NULL,                       /* get_numa_id */
> -    NULL,                       /* set_multiq */
> +    NULL,                       /* set_tx_multiq */
>  
>      netdev_dummy_send,          /* send */
>      NULL,                       /* send_wait */
> diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
> index 427b3e2..3cc39b4 100644
> --- a/lib/netdev-linux.c
> +++ b/lib/netdev-linux.c
> @@ -2766,7 +2766,7 @@ netdev_linux_update_flags(struct netdev *netdev_, enum netdev_flags off,
>      NULL,                       /* push header */               \
>      NULL,                       /* pop header */                \
>      NULL,                       /* get_numa_id */               \
> -    NULL,                       /* set_multiq */                \
> +    NULL,                       /* set_tx_multiq */             \
>                                                                  \
>      netdev_linux_send,                                          \
>      netdev_linux_send_wait,                                     \
> diff --git a/lib/netdev-provider.h b/lib/netdev-provider.h
> index 853fc44..be31e31 100644
> --- a/lib/netdev-provider.h
> +++ b/lib/netdev-provider.h
> @@ -67,8 +67,6 @@ struct netdev {
>       * modify them. */
>      int n_txq;
>      int n_rxq;
> -    /* Number of rx queues requested by user. */
> -    int requested_n_rxq;
>      int ref_cnt;                        /* Times this devices was opened. */
>      struct shash_node *node;            /* Pointer to element in global map. */
>      struct ovs_list saved_flags_list; /* Contains "struct netdev_saved_flags". */
> @@ -298,13 +296,8 @@ struct netdev_class {
>       * such info, returns NETDEV_NUMA_UNSPEC. */
>      int (*get_numa_id)(const struct netdev *netdev);
>  
> -    /* Configures the number of tx queues and rx queues of 'netdev'.
> -     * Return 0 if successful, otherwise a positive errno value.
> -     *
> -     * 'n_rxq' specifies the maximum number of receive queues to create.
> -     * The netdev provider might choose to create less (e.g. if the hardware
> -     * supports only a smaller number).  The actual number of queues created
> -     * is stored in the 'netdev->n_rxq' field.
> +    /* Configures the number of tx queues of 'netdev'. Returns 0 if successful,
> +     * otherwise a positive errno value.
>       *
>       * 'n_txq' specifies the exact number of transmission queues to create.
>       * The caller will call netdev_send() concurrently from 'n_txq' different
> @@ -312,12 +305,12 @@ struct netdev_class {
>       * making sure that these concurrent calls do not create a race condition
>       * by using multiple hw queues or locking.
>       *
> -     * On error, the tx queue and rx queue configuration is indeterminant.
> -     * Caller should make decision on whether to restore the previous or
> -     * the default configuration.  Also, caller must make sure there is no
> -     * other thread accessing the queues at the same time. */
> -    int (*set_multiq)(struct netdev *netdev, unsigned int n_txq,
> -                      unsigned int n_rxq);
> +     * The caller will call netdev_reconfigure() (if necessary) before using
> +     * netdev_send() on any of the newly configured queues, giving the provider
> +     * a chance to adjust its settings.
> +     *
> +     * On error, the tx queue configuration is unchanged. */
> +    int (*set_tx_multiq)(struct netdev *netdev, unsigned int n_txq);
>  
>      /* Sends buffers on 'netdev'.
>       * Returns 0 if successful (for every buffer), otherwise a positive errno
> diff --git a/lib/netdev-vport.c b/lib/netdev-vport.c
> index 4a1d711..4e5137e 100644
> --- a/lib/netdev-vport.c
> +++ b/lib/netdev-vport.c
> @@ -1488,7 +1488,7 @@ netdev_vport_range(struct unixctl_conn *conn, int argc,
>      PUSH_HEADER,                                            \
>      POP_HEADER,                                             \
>      NULL,                       /* get_numa_id */           \
> -    NULL,                       /* set_multiq */            \
> +    NULL,                       /* set_tx_multiq */         \
>                                                              \
>      NULL,                       /* send */                  \
>      NULL,                       /* send_wait */             \
> diff --git a/lib/netdev.c b/lib/netdev.c
> index d226bb1..a3cf2fe 100644
> --- a/lib/netdev.c
> +++ b/lib/netdev.c
> @@ -114,12 +114,6 @@ netdev_n_rxq(const struct netdev *netdev)
>      return netdev->n_rxq;
>  }
>  
> -int
> -netdev_requested_n_rxq(const struct netdev *netdev)
> -{
> -    return netdev->requested_n_rxq;
> -}
> -
>  bool
>  netdev_is_pmd(const struct netdev *netdev)
>  {
> @@ -390,7 +384,6 @@ netdev_open(const char *name, const char *type, struct netdev **netdevp)
>                  /* By default enable one tx and rx queue per netdev. */
>                  netdev->n_txq = netdev->netdev_class->send ? 1 : 0;
>                  netdev->n_rxq = netdev->netdev_class->rxq_alloc ? 1 : 0;
> -                netdev->requested_n_rxq = netdev->n_rxq;
>  
>                  ovs_list_init(&netdev->saved_flags_list);
>  
> @@ -691,37 +684,30 @@ netdev_rxq_drain(struct netdev_rxq *rx)
>              : 0);
>  }
>  
> -/* Configures the number of tx queues and rx queues of 'netdev'.
> - * Return 0 if successful, otherwise a positive errno value.
> - *
> - * 'n_rxq' specifies the maximum number of receive queues to create.
> - * The netdev provider might choose to create less (e.g. if the hardware
> - * supports only a smaller number).  The caller can check how many have been
> - * actually created by calling 'netdev_n_rxq()'
> +/* Configures the number of tx queues of 'netdev'. Returns 0 if successful,
> + * otherwise a positive errno value.
>   *
>   * 'n_txq' specifies the exact number of transmission queues to create.
>   * If this function returns successfully, the caller can make 'n_txq'
>   * concurrent calls to netdev_send() (each one with a different 'qid' in the
>   * range [0..'n_txq'-1]).
>   *
> - * On error, the tx queue and rx queue configuration is indeterminant.
> - * Caller should make decision on whether to restore the previous or
> - * the default configuration.  Also, caller must make sure there is no
> - * other thread accessing the queues at the same time. */
> + * The change might not effective immediately.  The caller must check if a
> + * reconfiguration is required with netdev_is_reconf_required() and eventually
> + * call netdev_reconfigure() before using the new queues.
> + *
> + * On error, the tx queue configuration is unchanged */
>  int
> -netdev_set_multiq(struct netdev *netdev, unsigned int n_txq,
> -                  unsigned int n_rxq)
> +netdev_set_tx_multiq(struct netdev *netdev, unsigned int n_txq)
>  {
>      int error;
>  
> -    error = (netdev->netdev_class->set_multiq
> -             ? netdev->netdev_class->set_multiq(netdev,
> -                                                MAX(n_txq, 1),
> -                                                MAX(n_rxq, 1))
> +    error = (netdev->netdev_class->set_tx_multiq
> +             ? netdev->netdev_class->set_tx_multiq(netdev, MAX(n_txq, 1))
>               : EOPNOTSUPP);
>  
>      if (error && error != EOPNOTSUPP) {
> -        VLOG_DBG_RL(&rl, "failed to set tx/rx queue for network device %s:"
> +        VLOG_DBG_RL(&rl, "failed to set tx queue for network device %s:"
>                      "%s", netdev_get_name(netdev), ovs_strerror(error));
>      }
>  
> diff --git a/lib/netdev.h b/lib/netdev.h
> index 857e2ae..aeac97c 100644
> --- a/lib/netdev.h
> +++ b/lib/netdev.h
> @@ -108,7 +108,6 @@ bool netdev_is_reserved_name(const char *name);
>  
>  int netdev_n_txq(const struct netdev *netdev);
>  int netdev_n_rxq(const struct netdev *netdev);
> -int netdev_requested_n_rxq(const struct netdev *netdev);
>  bool netdev_is_pmd(const struct netdev *netdev);
>  
>  /* Open and close. */
> @@ -134,7 +133,7 @@ const char *netdev_get_type_from_name(const char *);
>  int netdev_get_mtu(const struct netdev *, int *mtup);
>  int netdev_set_mtu(const struct netdev *, int mtu);
>  int netdev_get_ifindex(const struct netdev *);
> -int netdev_set_multiq(struct netdev *, unsigned int n_txq, unsigned int n_rxq);
> +int netdev_set_tx_multiq(struct netdev *, unsigned int n_txq);
>  
>  /* Packet reception. */
>  int netdev_rxq_open(struct netdev *, struct netdev_rxq **, int id);
> 



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