[ovs-dev] [RFC v3 PATCH 3/5] dpif-netdev: Skip encap action during datapath execution
Sriharsha Basavapatna
sriharsha.basavapatna at broadcom.com
Mon Jun 1 17:29:32 UTC 2020
On Mon, Jun 1, 2020 at 9:18 PM Eli Britstein <elibr at mellanox.com> wrote:
>
>
> On 6/1/2020 6:15 PM, Sriharsha Basavapatna wrote:
> > On Mon, Jun 1, 2020 at 7:58 PM Eli Britstein <elibr at mellanox.com> wrote:
> >>
> >> On 5/28/2020 11:19 AM, Sriharsha Basavapatna wrote:
> >>> In this patch we check if action processing (apart from OUTPUT action),
> >>> should be skipped for a given dp_netdev_flow. Specifically, we check if
> >>> the action is TNL_PUSH and if it has been offloaded to HW, then we do not
> >>> push the tunnel header in SW. The datapath only executes the OUTPUT action.
> >>> The packet will be encapsulated in HW during transmit.
> >>>
> >>> Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna at broadcom.com>
> >>> ---
> >>> lib/dpif-netdev.c | 46 ++++++++++++++++++++++++++++++++++++----------
> >>> 1 file changed, 36 insertions(+), 10 deletions(-)
> >>>
> >>> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> >>> index 781b233f4..3e175c25e 100644
> >>> --- a/lib/dpif-netdev.c
> >>> +++ b/lib/dpif-netdev.c
> >>> @@ -112,6 +112,7 @@ COVERAGE_DEFINE(datapath_drop_recirc_error);
> >>> COVERAGE_DEFINE(datapath_drop_invalid_port);
> >>> COVERAGE_DEFINE(datapath_drop_invalid_tnl_port);
> >>> COVERAGE_DEFINE(datapath_drop_rx_invalid_packet);
> >>> +COVERAGE_DEFINE(datapath_skip_tunnel_push);
> >>>
> >>> /* Protects against changes to 'dp_netdevs'. */
> >>> static struct ovs_mutex dp_netdev_mutex = OVS_MUTEX_INITIALIZER;
> >>> @@ -538,6 +539,16 @@ struct dp_netdev_flow {
> >>> bool dead;
> >>> uint32_t mark; /* Unique flow mark assigned to a flow */
> >>>
> >>> + /* The next two members are used to support partial offloading of
> >>> + * actions. The boolean flag tells if this flow has its actions partially
> >>> + * offloaded. The egress port# tells if the action should be offloaded
> >>> + * on the egress (output) port instead of the in-port for the flow. Note
> >>> + * that we support flows with a single egress port action.
> >>> + * (see MAX_ACTION_ATTRS for related comments).
> >>> + */
> >>> + bool partial_actions_offloaded;
> >>> + odp_port_t egress_offload_port;
> >>> +
> >>> /* Statistics. */
> >>> struct dp_netdev_flow_stats stats;
> >>>
> >>> @@ -791,7 +802,8 @@ static void dp_netdev_execute_actions(struct dp_netdev_pmd_thread *pmd,
> >>> bool should_steal,
> >>> const struct flow *flow,
> >>> const struct nlattr *actions,
> >>> - size_t actions_len);
> >>> + size_t actions_len,
> >>> + const struct dp_netdev_flow *dp_flow);
> >>> static void dp_netdev_input(struct dp_netdev_pmd_thread *,
> >>> struct dp_packet_batch *, odp_port_t port_no);
> >>> static void dp_netdev_recirculate(struct dp_netdev_pmd_thread *,
> >>> @@ -3828,7 +3840,7 @@ dpif_netdev_execute(struct dpif *dpif, struct dpif_execute *execute)
> >>> dp_packet_batch_init_packet(&pp, execute->packet);
> >>> pp.do_not_steal = true;
> >>> dp_netdev_execute_actions(pmd, &pp, false, execute->flow,
> >>> - execute->actions, execute->actions_len);
> >>> + execute->actions, execute->actions_len, NULL);
> >>> dp_netdev_pmd_flush_output_packets(pmd, true);
> >>>
> >>> if (pmd->core_id == NON_PMD_CORE_ID) {
> >>> @@ -6456,7 +6468,7 @@ packet_batch_per_flow_execute(struct packet_batch_per_flow *batch,
> >>> actions = dp_netdev_flow_get_actions(flow);
> >>>
> >>> dp_netdev_execute_actions(pmd, &batch->array, true, &flow->flow,
> >>> - actions->actions, actions->size);
> >>> + actions->actions, actions->size, flow);
> >>> }
> >>>
> >>> static inline void
> >>> @@ -6764,7 +6776,7 @@ handle_packet_upcall(struct dp_netdev_pmd_thread *pmd,
> >>> * we'll send the packet up twice. */
> >>> dp_packet_batch_init_packet(&b, packet);
> >>> dp_netdev_execute_actions(pmd, &b, true, &match.flow,
> >>> - actions->data, actions->size);
> >>> + actions->data, actions->size, NULL);
> >>>
> >>> add_actions = put_actions->size ? put_actions : actions;
> >>> if (OVS_LIKELY(error != ENOSPC)) {
> >>> @@ -6999,6 +7011,7 @@ dp_netdev_recirculate(struct dp_netdev_pmd_thread *pmd,
> >>> struct dp_netdev_execute_aux {
> >>> struct dp_netdev_pmd_thread *pmd;
> >>> const struct flow *flow;
> >>> + const struct dp_netdev_flow *dp_flow; /* for partial action offload */
> >>> };
> >>>
> >>> static void
> >>> @@ -7143,7 +7156,7 @@ dp_execute_userspace_action(struct dp_netdev_pmd_thread *pmd,
> >>> if (!error || error == ENOSPC) {
> >>> dp_packet_batch_init_packet(&b, packet);
> >>> dp_netdev_execute_actions(pmd, &b, should_steal, flow,
> >>> - actions->data, actions->size);
> >>> + actions->data, actions->size, NULL);
> >>> } else if (should_steal) {
> >>> dp_packet_delete(packet);
> >>> COVERAGE_INC(datapath_drop_userspace_action_error);
> >>> @@ -7162,6 +7175,7 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
> >>> int type = nl_attr_type(a);
> >>> struct tx_port *p;
> >>> uint32_t packet_count, packets_dropped;
> >>> + struct dp_netdev_flow *dp_flow = aux->dp_flow;
> >>>
> >>> switch ((enum ovs_action_attr)type) {
> >>> case OVS_ACTION_ATTR_OUTPUT:
> >>> @@ -7219,9 +7233,20 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
> >>> }
> >>> dp_packet_batch_apply_cutlen(packets_);
> >>> packet_count = dp_packet_batch_size(packets_);
> >>> - if (push_tnl_action(pmd, a, packets_)) {
> >>> - COVERAGE_ADD(datapath_drop_tunnel_push_error,
> >>> - packet_count);
> >>> + /* Execute tnl_push action in SW, if it is not offloaded as a partial
> >>> + * action in HW. Otherwise, HW pushes the tunnel header during output
> >>> + * processing. There's a small window here in which the offload thread
> >>> + * offloads the flow, but the partial_actions_offloaded flag is still
> >>> + * not set. In this case, as the packet is already encapsulated, it
> >>> + * wouldn't match the offloaded flow and the action won't be executed
> >>> + * in HW.
> >> I have created a scenario in which it would hit. Just set the inner
> >> properties as the outer. Of course it is not the common case, but it
> >> takes only an example.
> >>
> >> Maybe add a logic not to offload if the matches would apply to the outer.
> > The outer properties specifically outer mac addresses are resolved by
> > OVS and then added to the header to be pushed. So I'm not sure how you
> > created this scenario if I'm correctly understanding your comment. Can
> > you please provide some details (example/commands that you used etc)
> > to hit the condition ? More clarity on this would help me to add the
> > additional logic to decline offload in this case.
> I've just manually set the properties of the inner according to my
> setup's outers. Regarding suggestion where to check, please see patch 5/5.
Outer headers can't be the same as inner, unless it is some kind of
misconfiguration. This misconfiguration could occur in full-offload
and non-offload modes too, not just in partial offload mode, right ?
It's like having duplicate addresses (address conflicts) in the
network. Code to handle this condition might look more confusing ?
There are facilities in the networking infrastructure to detect/report
such conditions and I feel flow offload layer is not the right place
to handle such issues. What do you think ?
Thanks,
-Harsha
> >
> > Thanks,
> > -Harsha
> >>> + */
> >>> + if (!dp_flow || !dp_flow->partial_actions_offloaded) {
> >>> + if (push_tnl_action(pmd, a, packets_)) {
> >>> + COVERAGE_ADD(datapath_drop_tunnel_push_error, packet_count);
> >>> + }
> >>> + } else {
> >>> + COVERAGE_ADD(datapath_skip_tunnel_push, packet_count);
> >>> }
> >>> return;
> >>>
> >>> @@ -7509,9 +7534,10 @@ static void
> >>> dp_netdev_execute_actions(struct dp_netdev_pmd_thread *pmd,
> >>> struct dp_packet_batch *packets,
> >>> bool should_steal, const struct flow *flow,
> >>> - const struct nlattr *actions, size_t actions_len)
> >>> + const struct nlattr *actions, size_t actions_len,
> >>> + const struct dp_netdev_flow *dp_flow)
> >>> {
> >>> - struct dp_netdev_execute_aux aux = { pmd, flow };
> >>> + struct dp_netdev_execute_aux aux = { pmd, flow, dp_flow };
> >>>
> >>> odp_execute_actions(&aux, packets, should_steal, actions,
> >>> actions_len, dp_execute_cb);
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