[ovs-dev,v7] dpif-netdev: proper tx queue id

Currently tx_qid is equal to pmd->core_id. This leads to unexpected
behavior if pmd-cpu-mask different from '/(0*)(1|3|7)?(f*)/',
e.g. if core_ids are not sequential, or doesn't start from 0, or both.

Example:
	starting 2 pmd threads with 1 port, 2 rxqs per port,
	pmd-cpu-mask = 00000014 and let dev->real_n_txq = 2

	It that case pmd_1->tx_qid = 2, pmd_2->tx_qid = 4 and
	txq_needs_locking = true (if device hasn't ovs_numa_get_n_cores()+1
	queues).

	In that case, after truncating in netdev_dpdk_send__():
		'qid = qid % dev->real_n_txq;'
	pmd_1: qid = 2 % 2 = 0
	pmd_2: qid = 4 % 2 = 0

	So, both threads will call dpdk_queue_pkts() with same qid = 0.
	This is unexpected behavior if there is 2 tx queues in device.
	Queue #1 will not be used and both threads will lock queue #0
	on each send.

Fix that by introducing per pmd thread hash map 'tx_queues', where will
be stored all available tx queues for that pmd thread with
port_no as a key(hash). All tx_qid-s will be unique per port and
sequential to prevent described unexpected mapping after truncating.

Implemented infrastructure can be used in the future to choose
between all tx queues available for that pmd thread.

Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
---
version 7:
	* rebased on current master
	* My comment for v6 that there is a race for total number of
	  threads was wrong. So, patch actually the same as v6.

version 6:
	* fixed assigning same txq to multiple pmd threads on different
	  NUMA sockets.
	* Changed logic of txq distribution in pmd_load_queues().
version 5:
	* txqs 0 from ports of non-pmd netdevs added to all pmd threads

version 4:
	* fixed distribution of tx queues if multiqueue is not supported

version 3:
	* fixed failing of unit tests by adding tx queues of non
	  pmd devices to non pmd thread. (they haven't been used by any thread)
	* pmd_flush_tx_queues --> dp_netdev_pmd_detach_tx_queues
	* function names changed to dp_netdev_*
	* dp_netdev_pmd_lookup_txq now looks by port_no.
	* removed unnecessary dp_netdev_lookup_port in dp_execute_cb
	  for OVS_ACTION_ATTR_OUTPUT.
	* refactoring


 lib/dpif-netdev.c | 189 ++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 163 insertions(+), 26 deletions(-)

Superseded by v8 : http://openvswitch.org/pipermail/dev/2015-December/063807.html

Best regards, Ilya Maximets.

On 14.12.2015 17:58, Ilya Maximets wrote:
> Currently tx_qid is equal to pmd->core_id. This leads to unexpected
> behavior if pmd-cpu-mask different from '/(0*)(1|3|7)?(f*)/',
> e.g. if core_ids are not sequential, or doesn't start from 0, or both.
> 
> Example:
> 	starting 2 pmd threads with 1 port, 2 rxqs per port,
> 	pmd-cpu-mask = 00000014 and let dev->real_n_txq = 2
> 
> 	It that case pmd_1->tx_qid = 2, pmd_2->tx_qid = 4 and
> 	txq_needs_locking = true (if device hasn't ovs_numa_get_n_cores()+1
> 	queues).
> 
> 	In that case, after truncating in netdev_dpdk_send__():
> 		'qid = qid % dev->real_n_txq;'
> 	pmd_1: qid = 2 % 2 = 0
> 	pmd_2: qid = 4 % 2 = 0
> 
> 	So, both threads will call dpdk_queue_pkts() with same qid = 0.
> 	This is unexpected behavior if there is 2 tx queues in device.
> 	Queue #1 will not be used and both threads will lock queue #0
> 	on each send.
> 
> Fix that by introducing per pmd thread hash map 'tx_queues', where will
> be stored all available tx queues for that pmd thread with
> port_no as a key(hash). All tx_qid-s will be unique per port and
> sequential to prevent described unexpected mapping after truncating.
> 
> Implemented infrastructure can be used in the future to choose
> between all tx queues available for that pmd thread.
> 
> Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
> ---
> version 7:
> 	* rebased on current master
> 	* My comment for v6 that there is a race for total number of
> 	  threads was wrong. So, patch actually the same as v6.
> 
> version 6:
> 	* fixed assigning same txq to multiple pmd threads on different
> 	  NUMA sockets.
> 	* Changed logic of txq distribution in pmd_load_queues().
> version 5:
> 	* txqs 0 from ports of non-pmd netdevs added to all pmd threads
> 
> version 4:
> 	* fixed distribution of tx queues if multiqueue is not supported
> 
> version 3:
> 	* fixed failing of unit tests by adding tx queues of non
> 	  pmd devices to non pmd thread. (they haven't been used by any thread)
> 	* pmd_flush_tx_queues --> dp_netdev_pmd_detach_tx_queues
> 	* function names changed to dp_netdev_*
> 	* dp_netdev_pmd_lookup_txq now looks by port_no.
> 	* removed unnecessary dp_netdev_lookup_port in dp_execute_cb
> 	  for OVS_ACTION_ATTR_OUTPUT.
> 	* refactoring
> 
> 
>  lib/dpif-netdev.c | 189 ++++++++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 163 insertions(+), 26 deletions(-)
> 
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index 8794ca0..1586852 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -372,6 +372,13 @@ struct dp_netdev_pmd_cycles {
>      atomic_ullong n[PMD_N_CYCLES];
>  };
>  
> +struct dp_netdev_pmd_txq {
> +    struct cmap_node node;        /* In owning dp_netdev_pmd_thread's */
> +                                  /* 'tx_queues'. */
> +    struct dp_netdev_port *port;
> +    int tx_qid;
> +};
> +
>  /* PMD: Poll modes drivers.  PMD accesses devices via polling to eliminate
>   * the performance overhead of interrupt processing.  Therefore netdev can
>   * not implement rx-wait for these devices.  dpif-netdev needs to poll
> @@ -425,10 +432,12 @@ struct dp_netdev_pmd_thread {
>      pthread_t thread;
>      int index;                      /* Idx of this pmd thread among pmd*/
>                                      /* threads on same numa node. */
> +    int global_index;               /* Idx of this pmd thread among all*/
> +                                    /* pmd threads in dp. */
>      unsigned core_id;               /* CPU core id of this pmd thread. */
>      int numa_id;                    /* numa node id of this pmd thread. */
> -    int tx_qid;                     /* Queue id used by this pmd thread to
> -                                     * send packets on all netdevs */
> +    struct cmap tx_queues;          /* Queue ids used by this pmd thread to
> +                                     * send packets to ports */
>  
>      /* Only a pmd thread can write on its own 'cycles' and 'stats'.
>       * The main thread keeps 'stats_zero' and 'cycles_zero' as base
> @@ -470,6 +479,15 @@ static void dp_netdev_input(struct dp_netdev_pmd_thread *,
>  
>  static void dp_netdev_disable_upcall(struct dp_netdev *);
>  void dp_netdev_pmd_reload_done(struct dp_netdev_pmd_thread *pmd);
> +static void dp_netdev_configure_non_pmd_txqs(struct dp_netdev_pmd_thread *pmd);
> +static void dp_netdev_pmd_add_txq(struct dp_netdev_pmd_thread *pmd,
> +                                  struct dp_netdev_port *port, int queue_id);
> +static void dp_netdev_pmd_del_txq(struct dp_netdev_pmd_thread *pmd,
> +                                  struct dp_netdev_pmd_txq *txq);
> +static void dp_netdev_pmd_detach_tx_queues(struct dp_netdev_pmd_thread *pmd);
> +static struct dp_netdev_pmd_txq *
> +dp_netdev_pmd_lookup_txq(const struct dp_netdev_pmd_thread *pmd,
> +                         odp_port_t port_no);
>  static void dp_netdev_configure_pmd(struct dp_netdev_pmd_thread *pmd,
>                                      struct dp_netdev *dp, int index,
>                                      unsigned core_id, int numa_id);
> @@ -1051,6 +1069,7 @@ do_add_port(struct dp_netdev *dp, const char *devname, const char *type,
>      struct netdev_saved_flags *sf;
>      struct dp_netdev_port *port;
>      struct netdev *netdev;
> +    struct dp_netdev_pmd_thread *non_pmd;
>      enum netdev_flags flags;
>      const char *open_type;
>      int error;
> @@ -1127,10 +1146,15 @@ do_add_port(struct dp_netdev *dp, const char *devname, const char *type,
>      ovs_refcount_init(&port->ref_cnt);
>      cmap_insert(&dp->ports, &port->node, hash_port_no(port_no));
>  
> -    if (netdev_is_pmd(netdev)) {
> -        dp_netdev_set_pmds_on_numa(dp, netdev_get_numa_id(netdev));
> -        dp_netdev_reload_pmds(dp);
> +    non_pmd = dp_netdev_get_pmd(dp, NON_PMD_CORE_ID);
> +    if (non_pmd) {
> +        dp_netdev_pmd_add_txq(non_pmd, port, ovs_numa_get_n_cores());
> +        dp_netdev_pmd_unref(non_pmd);
>      }
> +    if (netdev_is_pmd(netdev))
> +        dp_netdev_set_pmds_on_numa(dp, netdev_get_numa_id(netdev));
> +    dp_netdev_reload_pmds(dp);
> +
>      seq_change(dp->port_seq);
>  
>      return 0;
> @@ -1272,6 +1296,13 @@ get_port_by_name(struct dp_netdev *dp,
>  }
>  
>  static int
> +get_n_pmd_threads(struct dp_netdev *dp)
> +{
> +    /* There is one non pmd thread in dp->poll_threads */
> +    return cmap_count(&dp->poll_threads) - 1;
> +}
> +
> +static int
>  get_n_pmd_threads_on_numa(struct dp_netdev *dp, int numa_id)
>  {
>      struct dp_netdev_pmd_thread *pmd;
> @@ -1308,18 +1339,32 @@ static void
>  do_del_port(struct dp_netdev *dp, struct dp_netdev_port *port)
>      OVS_REQUIRES(dp->port_mutex)
>  {
> +    struct dp_netdev_pmd_thread *non_pmd;
> +
>      cmap_remove(&dp->ports, &port->node, hash_odp_port(port->port_no));
>      seq_change(dp->port_seq);
> +
> +    non_pmd = dp_netdev_get_pmd(dp, NON_PMD_CORE_ID);
> +    if (non_pmd) {
> +        /* There is only one txq for each port for non pmd thread */
> +        struct dp_netdev_pmd_txq *txq;
> +        txq = dp_netdev_pmd_lookup_txq(non_pmd, port->port_no);
> +        if (OVS_LIKELY(txq))
> +            dp_netdev_pmd_del_txq(non_pmd, txq);
> +        dp_netdev_pmd_unref(non_pmd);
> +    }
> +
>      if (netdev_is_pmd(port->netdev)) {
>          int numa_id = netdev_get_numa_id(port->netdev);
>  
>          /* If there is no netdev on the numa node, deletes the pmd threads
> -         * for that numa.  Else, just reloads the queues.  */
> +         * for that numa. */
>          if (!has_pmd_port_for_numa(dp, numa_id)) {
>              dp_netdev_del_pmds_on_numa(dp, numa_id);
>          }
> -        dp_netdev_reload_pmds(dp);
>      }
> +    /* Reload queues of pmd threads. */
> +    dp_netdev_reload_pmds(dp);
>  
>      port_unref(port);
>  }
> @@ -2583,6 +2628,80 @@ dpif_netdev_wait(struct dpif *dpif)
>      seq_wait(tnl_conf_seq, dp->last_tnl_conf_seq);
>  }
>  
> +static void
> +dp_netdev_pmd_add_txq(struct dp_netdev_pmd_thread *pmd,
> +                      struct dp_netdev_port *port, int queue_id)
> +{
> +    if (port_try_ref(port)) {
> +        struct dp_netdev_pmd_txq * txq = xmalloc(sizeof *txq);
> +        txq->port = port;
> +        txq->tx_qid = queue_id;
> +        cmap_insert(&pmd->tx_queues, &txq->node,
> +                        hash_port_no(port->port_no));
> +    }
> +}
> +
> +/* Configures tx_queues for non pmd thread. */
> +static void
> +dp_netdev_configure_non_pmd_txqs(struct dp_netdev_pmd_thread *pmd)
> +{
> +    if (!cmap_is_empty(&pmd->tx_queues))
> +        dp_netdev_pmd_detach_tx_queues(pmd);
> +
> +    struct dp_netdev_port *port;
> +    CMAP_FOR_EACH (port, node, &pmd->dp->ports) {
> +        dp_netdev_pmd_add_txq(pmd, port, ovs_numa_get_n_cores());
> +    }
> +}
> +
> +static void
> +dp_netdev_pmd_del_txq(struct dp_netdev_pmd_thread *pmd,
> +                      struct dp_netdev_pmd_txq *txq)
> +{
> +    cmap_remove(&pmd->tx_queues, &txq->node,
> +                hash_port_no(txq->port->port_no));
> +    port_unref(txq->port);
> +    free(txq);
> +}
> +
> +/* Removes all queues from 'tx_queues' of pmd thread. */
> +static void
> +dp_netdev_pmd_detach_tx_queues(struct dp_netdev_pmd_thread *pmd)
> +{
> +    struct dp_netdev_pmd_txq *txq;
> +
> +    CMAP_FOR_EACH (txq, node, &pmd->tx_queues) {
> +        dp_netdev_pmd_del_txq(pmd, txq);
> +    }
> +}
> +
> +static void OVS_UNUSED
> +dp_netdev_pmd_tx_queues_print(struct dp_netdev_pmd_thread *pmd)
> +{
> +    struct dp_netdev_pmd_txq *txq;
> +
> +    CMAP_FOR_EACH (txq, node, &pmd->tx_queues) {
> +        VLOG_INFO("Core_id: %d, Port: %s, tx_qid: %d\n",
> +                   pmd->core_id, netdev_get_name(txq->port->netdev),
> +                   txq->tx_qid);
> +    }
> +}
> +
> +static struct dp_netdev_pmd_txq *
> +dp_netdev_pmd_lookup_txq(const struct dp_netdev_pmd_thread *pmd,
> +                         odp_port_t port_no)
> +{
> +    struct dp_netdev_pmd_txq *txq;
> +
> +    CMAP_FOR_EACH_WITH_HASH (txq, node, hash_port_no(port_no),
> +                             &pmd->tx_queues) {
> +        if (txq->port->port_no == port_no) {
> +            return txq;
> +        }
> +    }
> +    return NULL;
> +}
> +
>  struct rxq_poll {
>      struct dp_netdev_port *port;
>      struct netdev_rxq *rx;
> @@ -2594,16 +2713,19 @@ pmd_load_queues(struct dp_netdev_pmd_thread *pmd,
>  {
>      struct rxq_poll *poll_list = *ppoll_list;
>      struct dp_netdev_port *port;
> -    int n_pmds_on_numa, index, i;
> +    int n_pmds, n_pmds_on_numa, rx_index, i, n_txq;
>  
>      /* Simple scheduler for netdev rx polling. */
> +    dp_netdev_pmd_detach_tx_queues(pmd);
> +
>      for (i = 0; i < poll_cnt; i++) {
>          port_unref(poll_list[i].port);
>      }
>  
>      poll_cnt = 0;
> +    n_pmds = get_n_pmd_threads(pmd->dp);
>      n_pmds_on_numa = get_n_pmd_threads_on_numa(pmd->dp, pmd->numa_id);
> -    index = 0;
> +    rx_index = 0;
>  
>      CMAP_FOR_EACH (port, node, &pmd->dp->ports) {
>          /* Calls port_try_ref() to prevent the main thread
> @@ -2614,7 +2736,7 @@ pmd_load_queues(struct dp_netdev_pmd_thread *pmd,
>                  int i;
>  
>                  for (i = 0; i < netdev_n_rxq(port->netdev); i++) {
> -                    if ((index % n_pmds_on_numa) == pmd->index) {
> +                    if ((rx_index % n_pmds_on_numa) == pmd->index) {
>                          poll_list = xrealloc(poll_list,
>                                          sizeof *poll_list * (poll_cnt + 1));
>  
> @@ -2623,9 +2745,26 @@ pmd_load_queues(struct dp_netdev_pmd_thread *pmd,
>                          poll_list[poll_cnt].rx = port->rxq[i];
>                          poll_cnt++;
>                      }
> -                    index++;
> +                    rx_index++;
> +                }
> +
> +            }
> +
> +            n_txq = netdev_n_txq(port->netdev);
> +            /* If multi-queue isn't supported by netdev, add txq 0
> +             * to that pmd thread. Otherwise, add all queues available
> +             * for that thread. pmd->global_index used to prevent
> +             * assigning same txq to multiple pmd threads on different
> +             * NUMA sockets.*/
> +            if (n_txq == 1) {
> +                dp_netdev_pmd_add_txq(pmd, port, 0);
> +            } else {
> +                /* Last queue reserved for non pmd threads */
> +                for (i = pmd->global_index; i < n_txq - 1; i += n_pmds) {
> +                    dp_netdev_pmd_add_txq(pmd, port, i);
>                  }
>              }
> +
>              /* Unrefs the port_try_ref(). */
>              port_unref(port);
>          }
> @@ -2694,6 +2833,8 @@ reload:
>          goto reload;
>      }
>  
> +    dp_netdev_pmd_detach_tx_queues(pmd);
> +
>      for (i = 0; i < poll_cnt; i++) {
>           port_unref(poll_list[i].port);
>      }
> @@ -2807,16 +2948,6 @@ dp_netdev_pmd_get_next(struct dp_netdev *dp, struct cmap_position *pos)
>      return next;
>  }
>  
> -static int
> -core_id_to_qid(unsigned core_id)
> -{
> -    if (core_id != NON_PMD_CORE_ID) {
> -        return core_id;
> -    } else {
> -        return ovs_numa_get_n_cores();
> -    }
> -}
> -
>  /* Configures the 'pmd' based on the input argument. */
>  static void
>  dp_netdev_configure_pmd(struct dp_netdev_pmd_thread *pmd, struct dp_netdev *dp,
> @@ -2824,8 +2955,8 @@ dp_netdev_configure_pmd(struct dp_netdev_pmd_thread *pmd, struct dp_netdev *dp,
>  {
>      pmd->dp = dp;
>      pmd->index = index;
> +    pmd->global_index = get_n_pmd_threads(dp);
>      pmd->core_id = core_id;
> -    pmd->tx_qid = core_id_to_qid(core_id);
>      pmd->numa_id = numa_id;
>  
>      ovs_refcount_init(&pmd->ref_cnt);
> @@ -2836,9 +2967,11 @@ dp_netdev_configure_pmd(struct dp_netdev_pmd_thread *pmd, struct dp_netdev *dp,
>      ovs_mutex_init(&pmd->flow_mutex);
>      dpcls_init(&pmd->cls);
>      cmap_init(&pmd->flow_table);
> -    /* init the 'flow_cache' since there is no
> +    cmap_init(&pmd->tx_queues);
> +    /* init the 'flow_cache' and 'tx_queues' since there is no
>       * actual thread created for NON_PMD_CORE_ID. */
>      if (core_id == NON_PMD_CORE_ID) {
> +        dp_netdev_configure_non_pmd_txqs(pmd);
>          emc_cache_init(&pmd->flow_cache);
>      }
>      cmap_insert(&dp->poll_threads, CONST_CAST(struct cmap_node *, &pmd->node),
> @@ -2851,6 +2984,7 @@ dp_netdev_destroy_pmd(struct dp_netdev_pmd_thread *pmd)
>      dp_netdev_pmd_flow_flush(pmd);
>      dpcls_destroy(&pmd->cls);
>      cmap_destroy(&pmd->flow_table);
> +    cmap_destroy(&pmd->tx_queues);
>      ovs_mutex_destroy(&pmd->flow_mutex);
>      latch_destroy(&pmd->exit_latch);
>      xpthread_cond_destroy(&pmd->cond);
> @@ -2867,6 +3001,7 @@ dp_netdev_del_pmd(struct dp_netdev *dp, struct dp_netdev_pmd_thread *pmd)
>       * no actual thread uninit it for NON_PMD_CORE_ID. */
>      if (pmd->core_id == NON_PMD_CORE_ID) {
>          emc_cache_uninit(&pmd->flow_cache);
> +        dp_netdev_pmd_detach_tx_queues(pmd);
>      } else {
>          latch_set(&pmd->exit_latch);
>          dp_netdev_reload_pmd__(pmd);
> @@ -3488,13 +3623,15 @@ dp_execute_cb(void *aux_, struct dp_packet **packets, int cnt,
>      struct dp_netdev *dp = pmd->dp;
>      int type = nl_attr_type(a);
>      struct dp_netdev_port *p;
> +    struct dp_netdev_pmd_txq *txq;
>      int i;
>  
>      switch ((enum ovs_action_attr)type) {
>      case OVS_ACTION_ATTR_OUTPUT:
> -        p = dp_netdev_lookup_port(dp, u32_to_odp(nl_attr_get_u32(a)));
> -        if (OVS_LIKELY(p)) {
> -            netdev_send(p->netdev, pmd->tx_qid, packets, cnt, may_steal);
> +        txq = dp_netdev_pmd_lookup_txq(pmd, u32_to_odp(nl_attr_get_u32(a)));
> +        if (OVS_LIKELY(txq)) {
> +            netdev_send(txq->port->netdev, txq->tx_qid,
> +                        packets, cnt, may_steal);
>              return;
>          }
>          break;
>