From e347acbc31111504c015531e8ad764a86d489309 Mon Sep 17 00:00:00 2001 From: Mohsin Kazmi Date: Mon, 28 Sep 2020 10:26:33 +0000 Subject: virtio: add packet buffering on tx Type: feature This patch adds packet buffering on tx for slow backend which have some jitter/delays in freeing the vrings. There are some limitations to the current design: 1) It only works in poll mode. 2) Atleast 1 rx queue of an interface (with buffering enabled) should be placed on each worker and main thread. Signed-off-by: Mohsin Kazmi Change-Id: Ib93c350298b228e80426e58ac77f3bbc93b8be27 --- src/vnet/devices/virtio/device.c | 63 +++++++++++++++++++++++++++++++++++----- 1 file changed, 56 insertions(+), 7 deletions(-) (limited to 'src/vnet/devices/virtio/device.c') diff --git a/src/vnet/devices/virtio/device.c b/src/vnet/devices/virtio/device.c index dcd565dd475..a414f821428 100644 --- a/src/vnet/devices/virtio/device.c +++ b/src/vnet/devices/virtio/device.c @@ -546,7 +546,7 @@ virtio_interface_tx_gso_inline (vlib_main_t * vm, vlib_node_runtime_t * node, virtio_vring_t *vring; u16 qid = vm->thread_index % vif->num_txqs; vring = vec_elt_at_index (vif->txq_vrings, qid); - u16 used, next, avail; + u16 used, next, avail, n_buffers = 0, n_buffers_left = 0; u16 sz = vring->size; u16 mask = sz - 1; u16 retry_count = 2; @@ -588,6 +588,42 @@ retry: else free_desc_count = sz - used; + if (vif->packet_buffering) + { + n_buffers = n_buffers_left = virtio_vring_n_buffers (vring->buffering); + + while (n_buffers_left && free_desc_count) + { + u16 n_added = 0; + + u32 bi = virtio_vring_buffering_read_from_front (vring->buffering); + if (bi == ~0) + break; + vlib_buffer_t *b0 = vlib_get_buffer (vm, bi); + if (b0->flags & VLIB_BUFFER_IS_TRACED) + { + virtio_tx_trace (vm, node, type, b0, buffers[0]); + } + n_added = + add_buffer_to_slot (vm, vif, type, vring, bi, free_desc_count, + avail, next, mask, do_gso, csum_offload, + node->node_index); + if (PREDICT_FALSE (n_added == 0)) + { + n_buffers_left--; + continue; + } + else if (PREDICT_FALSE (n_added > free_desc_count)) + break; + + avail++; + next = (next + n_added) & mask; + used += n_added; + n_buffers_left--; + free_desc_count -= n_added; + } + } + while (n_left && free_desc_count) { u16 n_added = 0; @@ -619,7 +655,7 @@ retry: free_desc_count -= n_added; } - if (n_left != frame->n_vectors) + if (n_left != frame->n_vectors || n_buffers != n_buffers_left) { CLIB_MEMORY_STORE_BARRIER (); vring->avail->idx = avail; @@ -634,9 +670,19 @@ retry: if (retry_count--) goto retry; - virtio_interface_drop_inline (vm, node->node_index, - buffers, n_left, - VIRTIO_TX_ERROR_NO_FREE_SLOTS); + if (vif->packet_buffering) + { + + u16 n_buffered = + virtio_vring_buffering_store_packets (vring->buffering, buffers, + n_left); + buffers += n_buffered; + n_left -= n_buffered; + } + if (n_left) + virtio_interface_drop_inline (vm, node->node_index, + buffers, n_left, + VIRTIO_TX_ERROR_NO_FREE_SLOTS); } clib_spinlock_unlock_if_init (&vring->lockp); @@ -740,20 +786,23 @@ virtio_interface_rx_mode_change (vnet_main_t * vnm, u32 hw_if_index, u32 qid, { /* only enable packet coalesce in poll mode */ gro_flow_table_set_is_enable (tx_vring->flow_table, 1); + /* only enable packet buffering in poll mode */ + virtio_vring_buffering_set_is_enable (tx_vring->buffering, 1); } rx_vring->avail->flags |= VRING_AVAIL_F_NO_INTERRUPT; } else { - if (vif->packet_coalesce) + if (vif->packet_coalesce || vif->packet_buffering) { virtio_log_warning (vif, - "interface %U is in interrupt mode, disabling packet coalescing", + "interface %U is in interrupt mode, disabling packet coalescing or buffering", format_vnet_sw_if_index_name, vnet_get_main (), vif->sw_if_index); vec_foreach (tx_vring, vif->txq_vrings) { gro_flow_table_set_is_enable (tx_vring->flow_table, 0); + virtio_vring_buffering_set_is_enable (tx_vring->buffering, 0); } } rx_vring->avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; -- cgit 1.2.3-korg