diff options
Diffstat (limited to 'src/vnet/devices/virtio/virtio_pre_input.c')
| -rw-r--r-- | src/vnet/devices/virtio/virtio_pre_input.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/src/vnet/devices/virtio/virtio_pre_input.c b/src/vnet/devices/virtio/virtio_pre_input.c new file mode 100644 index 00000000000..ee6e848310d --- /dev/null +++ b/src/vnet/devices/virtio/virtio_pre_input.c @@ -0,0 +1,159 @@ +/* + *------------------------------------------------------------------ + * Copyright (c) 2021 Cisco and/or its affiliates. + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at: + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + *------------------------------------------------------------------ + */ + +#include <vlib/vlib.h> +#include <vnet/gso/gro_func.h> +#include <vnet/interface/tx_queue_funcs.h> +#include <vnet/devices/virtio/virtio.h> +#include <vnet/devices/virtio/virtio_inline.h> + +static_always_inline uword +virtio_pre_input_inline (vlib_main_t *vm, virtio_vring_t *txq_vring, + vnet_hw_if_tx_queue_t *txq, u8 packet_coalesce, + u8 packet_buffering) +{ + if (txq->shared_queue) + { + if (clib_spinlock_trylock (&txq_vring->lockp)) + { + if (virtio_txq_is_scheduled (txq_vring)) + return 0; + if (packet_coalesce) + vnet_gro_flow_table_schedule_node_on_dispatcher ( + vm, txq, txq_vring->flow_table); + else if (packet_buffering) + virtio_vring_buffering_schedule_node_on_dispatcher ( + vm, txq, txq_vring->buffering); + virtio_txq_set_scheduled (txq_vring); + clib_spinlock_unlock (&txq_vring->lockp); + } + } + else + { + if (packet_coalesce) + vnet_gro_flow_table_schedule_node_on_dispatcher ( + vm, txq, txq_vring->flow_table); + else if (packet_buffering) + virtio_vring_buffering_schedule_node_on_dispatcher ( + vm, txq, txq_vring->buffering); + } + return 0; +} + +static uword +virtio_pre_input (vlib_main_t *vm, vlib_node_runtime_t *node, + vlib_frame_t *frame) +{ + virtio_main_t *vim = &virtio_main; + vnet_main_t *vnm = vnet_get_main (); + virtio_if_t *vif; + + pool_foreach (vif, vim->interfaces) + { + if (vif->packet_coalesce || vif->packet_buffering) + { + virtio_vring_t *txq_vring; + vec_foreach (txq_vring, vif->txq_vrings) + { + vnet_hw_if_tx_queue_t *txq = + vnet_hw_if_get_tx_queue (vnm, txq_vring->queue_index); + if (clib_bitmap_get (txq->threads, vm->thread_index) == 1) + virtio_pre_input_inline (vm, txq_vring, txq, + vif->packet_coalesce, + vif->packet_buffering); + } + } + } + + return 0; +} + +/** + * virtio interfaces support packet coalescing and buffering which + * depends on timer expiry to flush the stored packets periodically. + * Previously, virtio input node checked timer expiry and scheduled + * tx queue accordingly. + * + * In poll mode, timer expiry was handled naturally, as input node + * runs periodically. In interrupt mode, virtio input node was dependent + * on the interrupts send from backend. Stored packets could starve, + * if there would not be interrupts to input node. + * + * This problem had been solved through a dedicated process node which + * periodically sends interrupt to virtio input node given coalescing + * or buffering feature were enabled on an interface. + * + * But that approach worked with following limitations: + * 1) Each VPP thread should have (atleast) 1 rx queue of an interface + * (with buffering enabled). And rxqs and txqs should be placed on the + * same thread. + * + * New design provides solution to above problem(s) without any limitation + * through (dedicated) pre-input node running on each VPP thread when + * atleast 1 virtio interface is enabled with coalescing or buffering. + */ +VLIB_REGISTER_NODE (virtio_pre_input_node) = { + .function = virtio_pre_input, + .type = VLIB_NODE_TYPE_PRE_INPUT, + .name = "virtio-pre-input", + .state = VLIB_NODE_STATE_DISABLED, +}; + +void +virtio_pre_input_node_enable (vlib_main_t *vm, virtio_if_t *vif) +{ + virtio_main_t *vim = &virtio_main; + if (vif->packet_coalesce || vif->packet_buffering) + { + vim->gro_or_buffering_if_count++; + if (vim->gro_or_buffering_if_count == 1) + { + foreach_vlib_main () + { + vlib_node_set_state (this_vlib_main, virtio_pre_input_node.index, + VLIB_NODE_STATE_POLLING); + } + } + } +} + +void +virtio_pre_input_node_disable (vlib_main_t *vm, virtio_if_t *vif) +{ + virtio_main_t *vim = &virtio_main; + if (vif->packet_coalesce || vif->packet_buffering) + { + if (vim->gro_or_buffering_if_count > 0) + vim->gro_or_buffering_if_count--; + if (vim->gro_or_buffering_if_count == 0) + { + foreach_vlib_main () + { + vlib_node_set_state (this_vlib_main, virtio_pre_input_node.index, + VLIB_NODE_STATE_DISABLED); + } + } + } +} + +/* + * fd.io coding-style-patch-verification: ON + * + * Local Variables: + * eval: (c-set-style "gnu") + * End: + */ |