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/*
*------------------------------------------------------------------
* 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, vnet_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))
goto unlock;
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);
unlock:
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)
{
vnet_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:
*/
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