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-rw-r--r--src/vnet/devices/virtio/device.c104
-rw-r--r--src/vnet/devices/virtio/pci.c1
-rw-r--r--src/vnet/devices/virtio/virtio.c5
-rw-r--r--src/vnet/devices/virtio/virtio.h1
4 files changed, 103 insertions, 8 deletions
diff --git a/src/vnet/devices/virtio/device.c b/src/vnet/devices/virtio/device.c
index e560c29e5e7..f5e9bbd441b 100644
--- a/src/vnet/devices/virtio/device.c
+++ b/src/vnet/devices/virtio/device.c
@@ -30,7 +30,8 @@
_(NO_FREE_SLOTS, "no free tx slots") \
_(TRUNC_PACKET, "packet > buffer size -- truncated in tx ring") \
_(PENDING_MSGS, "pending msgs in tx ring") \
-_(NO_TX_QUEUES, "no tx queues")
+_(NO_TX_QUEUES, "no tx queues") \
+_(OUT_OF_ORDER, "out-of-order buffers in used ring")
typedef enum
{
@@ -91,13 +92,31 @@ format_virtio_tx_trace (u8 * s, va_list * args)
}
static_always_inline void
-virtio_free_used_device_desc (vlib_main_t * vm, virtio_vring_t * vring)
+virtio_memset_ring_u32 (u32 * ring, u32 start, u32 ring_size, u32 n_buffers)
+{
+ ASSERT (n_buffers <= ring_size);
+
+ if (PREDICT_TRUE (start + n_buffers <= ring_size))
+ {
+ clib_memset_u32 (ring + start, ~0, n_buffers);
+ }
+ else
+ {
+ clib_memset_u32 (ring + start, ~0, ring_size - start);
+ clib_memset_u32 (ring, ~0, n_buffers - (ring_size - start));
+ }
+}
+
+static_always_inline void
+virtio_free_used_device_desc (vlib_main_t * vm, virtio_vring_t * vring,
+ uword node_index)
{
u16 used = vring->desc_in_use;
u16 sz = vring->size;
u16 mask = sz - 1;
u16 last = vring->last_used_idx;
u16 n_left = vring->used->idx - last;
+ u16 out_of_order_count = 0;
if (n_left == 0)
return;
@@ -108,7 +127,7 @@ virtio_free_used_device_desc (vlib_main_t * vm, virtio_vring_t * vring)
u16 slot, n_buffers;
slot = n_buffers = e->id;
- while (e->id == n_buffers)
+ while (e->id == (n_buffers & mask))
{
n_left--;
last++;
@@ -119,18 +138,29 @@ virtio_free_used_device_desc (vlib_main_t * vm, virtio_vring_t * vring)
}
vlib_buffer_free_from_ring (vm, vring->buffers, slot,
sz, (n_buffers - slot));
+ virtio_memset_ring_u32 (vring->buffers, slot, sz, (n_buffers - slot));
used -= (n_buffers - slot);
if (n_left > 0)
{
- slot = e->id;
-
- vlib_buffer_free (vm, &vring->buffers[slot], 1);
+ vlib_buffer_free (vm, &vring->buffers[e->id], 1);
+ vring->buffers[e->id] = ~0;
used--;
last++;
n_left--;
+ out_of_order_count++;
+ vring->flags |= VRING_TX_OUT_OF_ORDER;
}
}
+
+ /*
+ * Some vhost-backends give buffers back in out-of-order fashion in used ring.
+ * It impacts the overall virtio-performance.
+ */
+ if (out_of_order_count)
+ vlib_error_count (vm, node_index, VIRTIO_TX_ERROR_OUT_OF_ORDER,
+ out_of_order_count);
+
vring->desc_in_use = used;
vring->last_used_idx = last;
}
@@ -263,6 +293,43 @@ add_buffer_to_slot (vlib_main_t * vm, virtio_if_t * vif,
return n_added;
}
+static_always_inline u32
+virtio_find_free_desc (virtio_vring_t * vring, u16 size, u16 mask,
+ u16 req, u16 next, u32 * first_free_desc_index,
+ u16 * free_desc_count)
+{
+ u16 start = 0;
+ /* next is used as hint: from where to start looking */
+ for (u16 i = 0; i < size; i++, next++)
+ {
+ if (vring->buffers[next & mask] == ~0)
+ {
+ if (*first_free_desc_index == ~0)
+ {
+ *first_free_desc_index = (next & mask);
+ start = i;
+ (*free_desc_count)++;
+ req--;
+ if (req == 0)
+ break;
+ }
+ else
+ {
+ if (start + *free_desc_count == i)
+ {
+ (*free_desc_count)++;
+ req--;
+ if (req == 0)
+ break;
+ }
+ else
+ break;
+ }
+ }
+ }
+ return *first_free_desc_index;
+}
+
static_always_inline uword
virtio_interface_tx_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
vlib_frame_t * frame, virtio_if_t * vif,
@@ -275,6 +342,7 @@ virtio_interface_tx_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
u16 used, next, avail;
u16 sz = vring->size;
u16 mask = sz - 1;
+ u16 retry_count = 2;
u32 *buffers = vlib_frame_vector_args (frame);
clib_spinlock_lock_if_init (&vring->lockp);
@@ -283,14 +351,30 @@ virtio_interface_tx_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
(vring->last_kick_avail_idx != vring->avail->idx))
virtio_kick (vm, vring, vif);
+retry:
/* free consumed buffers */
- virtio_free_used_device_desc (vm, vring);
+ virtio_free_used_device_desc (vm, vring, node->node_index);
used = vring->desc_in_use;
next = vring->desc_next;
avail = vring->avail->idx;
- while (n_left && used < sz)
+ u16 free_desc_count = 0;
+
+ if (PREDICT_FALSE (vring->flags & VRING_TX_OUT_OF_ORDER))
+ {
+ u32 first_free_desc_index = ~0;
+
+ virtio_find_free_desc (vring, sz, mask, n_left, next,
+ &first_free_desc_index, &free_desc_count);
+
+ if (free_desc_count)
+ next = first_free_desc_index;
+ }
+ else
+ free_desc_count = sz - used;
+
+ while (n_left && free_desc_count)
{
u16 n_added = 0;
n_added =
@@ -303,6 +387,7 @@ virtio_interface_tx_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
used += n_added;
buffers++;
n_left--;
+ free_desc_count--;
}
if (n_left != frame->n_vectors)
@@ -317,6 +402,9 @@ virtio_interface_tx_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
if (n_left)
{
+ if (retry_count--)
+ goto retry;
+
vlib_error_count (vm, node->node_index, VIRTIO_TX_ERROR_NO_FREE_SLOTS,
n_left);
vlib_buffer_free (vm, buffers, n_left);
diff --git a/src/vnet/devices/virtio/pci.c b/src/vnet/devices/virtio/pci.c
index 7ebc0d359e7..10820c8d8f2 100644
--- a/src/vnet/devices/virtio/pci.c
+++ b/src/vnet/devices/virtio/pci.c
@@ -719,6 +719,7 @@ virtio_pci_vring_init (vlib_main_t * vm, virtio_if_t * vif, u16 queue_num)
{
virtio_log_debug (vim, vif, "tx-queue: number %u, size %u", queue_num,
queue_size);
+ clib_memset_u32 (vring->buffers, ~0, queue_size);
}
else
{
diff --git a/src/vnet/devices/virtio/virtio.c b/src/vnet/devices/virtio/virtio.c
index 88511d74411..5e23bef0889 100644
--- a/src/vnet/devices/virtio/virtio.c
+++ b/src/vnet/devices/virtio/virtio.c
@@ -117,6 +117,11 @@ virtio_vring_init (vlib_main_t * vm, virtio_if_t * vif, u16 idx, u16 sz)
ASSERT (vring->buffers == 0);
vec_validate_aligned (vring->buffers, sz, CLIB_CACHE_LINE_BYTES);
+ if (idx & 1)
+ {
+ clib_memset_u32 (vring->buffers, ~0, sz);
+ }
+
vring->size = sz;
vring->call_fd = eventfd (0, EFD_NONBLOCK | EFD_CLOEXEC);
vring->kick_fd = eventfd (0, EFD_CLOEXEC);
diff --git a/src/vnet/devices/virtio/virtio.h b/src/vnet/devices/virtio/virtio.h
index 070d0a45262..03654b63b73 100644
--- a/src/vnet/devices/virtio/virtio.h
+++ b/src/vnet/devices/virtio/virtio.h
@@ -112,6 +112,7 @@ typedef struct
u8 buffer_pool_index;
u16 size;
u16 queue_id;
+#define VRING_TX_OUT_OF_ORDER 1
u16 flags;
u32 call_file_index;
u32 *buffers;