This patch was discussed here already. https://mail.openvswitch.org/pipermail/ovs-dev/2017-July/336145.html
We think it needs more work. -----Original Message----- From: Ilya Maximets <[email protected]> Date: Friday, July 21, 2017 at 5:51 AM To: "[email protected]" <[email protected]>, Darrell Ball <[email protected]> Cc: Heetae Ahn <[email protected]>, Daniele Di Proietto <[email protected]>, Ben Pfaff <[email protected]>, Pravin Shelar <[email protected]>, Ciara Loftus <[email protected]>, Ian Stokes <[email protected]>, Kevin Traynor <[email protected]>, Cian Ferriter <[email protected]>, Mark Kavanagh <[email protected]>, Ilya Maximets <[email protected]> Subject: [PATCH v4 2/3] dpif-netdev: Avoid port's reconfiguration on pmd-cpu-mask changes. Reconfiguration of HW NICs may lead to packet drops. In current model all physical ports will be reconfigured each time number of PMD threads changed. Since we not stopping threads on pmd-cpu-mask changes, this patch will help to further decrease port's downtime by setting the maximum possible number of wanted tx queues to avoid unnecessary reconfigurations. Signed-off-by: Ilya Maximets <[email protected]> Tested-by: Ian Stokes <[email protected]> Acked-by: Ian Stokes <[email protected]> --- lib/dpif-netdev.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c index 4de3678..a1e8c56 100644 --- a/lib/dpif-netdev.c +++ b/lib/dpif-netdev.c @@ -3457,7 +3457,7 @@ reconfigure_datapath(struct dp_netdev *dp) { struct dp_netdev_pmd_thread *pmd; struct dp_netdev_port *port; - int wanted_txqs; + int needed_txqs, wanted_txqs; dp->last_reconfigure_seq = seq_read(dp->reconfigure_seq); @@ -3465,7 +3465,15 @@ reconfigure_datapath(struct dp_netdev *dp) * on the system and the user configuration. */ reconfigure_pmd_threads(dp); - wanted_txqs = cmap_count(&dp->poll_threads); + /* We need 1 Tx queue for each thread to avoid locking, but we will try + * to allocate the maximum possible value to minimize the number of port + * reconfigurations. */ + needed_txqs = cmap_count(&dp->poll_threads); + /* (n_cores + 1) is the maximum that we might need to have. + * Additional queue is for non-PMD threads. */ + wanted_txqs = ovs_numa_get_n_cores(); + ovs_assert(wanted_txqs != OVS_CORE_UNSPEC); + wanted_txqs++; /* The number of pmd threads might have changed, or a port can be new: * adjust the txqs. */ @@ -3478,9 +3486,17 @@ reconfigure_datapath(struct dp_netdev *dp) /* Check for all the ports that need reconfiguration. We cache this in * 'port->need_reconfigure', because netdev_is_reconf_required() can - * change at any time. */ + * change at any time. + * Also mark for reconfiguration all ports which will likely change their + * 'dynamic_txqs' parameter. It's required to stop using them before + * changing this setting and it's simpler to mark ports here and allow + * 'pmd_remove_stale_ports' to remove them from threads. There will be + * no actual reconfiguration in 'port_reconfigure' because it's + * unnecessary. */ HMAP_FOR_EACH (port, node, &dp->ports) { - if (netdev_is_reconf_required(port->netdev)) { + if (netdev_is_reconf_required(port->netdev) + || (port->dynamic_txqs + != (netdev_n_txq(port->netdev) < needed_txqs))) { port->need_reconfigure = true; } } @@ -3515,7 +3531,7 @@ reconfigure_datapath(struct dp_netdev *dp) seq_change(dp->port_seq); port_destroy(port); } else { - port->dynamic_txqs = netdev_n_txq(port->netdev) < wanted_txqs; + port->dynamic_txqs = netdev_n_txq(port->netdev) < needed_txqs; } } -- 2.7.4 _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
