vlib: handoff rework
Type: improvement
Change-Id: I1e199ae31e969154319e94c5cd286b8d8adc6660
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vlib/buffer_funcs.c b/src/vlib/buffer_funcs.c
index 83ff296..624b6e6 100644
--- a/src/vlib/buffer_funcs.c
+++ b/src/vlib/buffer_funcs.c
@@ -87,7 +87,10 @@
while (n_left)
{
while (PREDICT_FALSE (used_elt_bmp[off] == ~0))
- off++;
+ {
+ off++;
+ ASSERT (off < ARRAY_LEN (used_elt_bmp));
+ }
next_index =
nexts[off * 64 + count_trailing_zeros (~used_elt_bmp[off])];
@@ -113,7 +116,10 @@
while (n_left)
{
while (PREDICT_FALSE (used_elt_bmp[off] == ~0))
- off++;
+ {
+ off++;
+ ASSERT (off < ARRAY_LEN (used_elt_bmp));
+ }
next_index =
nexts[off * 64 + count_trailing_zeros (~used_elt_bmp[off])];
@@ -161,100 +167,88 @@
}
CLIB_MARCH_FN_REGISTRATION (vlib_buffer_enqueue_to_single_next_fn);
-u32 __clib_section (".vlib_buffer_enqueue_to_thread_fn")
-CLIB_MULTIARCH_FN (vlib_buffer_enqueue_to_thread_fn)
-(vlib_main_t *vm, vlib_node_runtime_t *node, u32 frame_queue_index,
- u32 *buffer_indices, u16 *thread_indices, u32 n_packets,
- int drop_on_congestion)
+static inline vlib_frame_queue_elt_t *
+vlib_get_frame_queue_elt (vlib_frame_queue_main_t *fqm, u32 index,
+ int dont_wait)
{
- vlib_thread_main_t *tm = vlib_get_thread_main ();
- vlib_frame_queue_main_t *fqm;
- vlib_frame_queue_per_thread_data_t *ptd;
- u32 n_left = n_packets;
- u32 drop_list[VLIB_FRAME_SIZE], *dbi = drop_list, n_drop = 0;
- vlib_frame_queue_elt_t *hf = 0;
- u32 n_left_to_next_thread = 0, *to_next_thread = 0;
- u32 next_thread_index, current_thread_index = ~0;
- int i;
+ vlib_frame_queue_t *fq;
+ u64 nelts, tail, new_tail;
- fqm = vec_elt_at_index (tm->frame_queue_mains, frame_queue_index);
- ptd = vec_elt_at_index (fqm->per_thread_data, vm->thread_index);
+ fq = fqm->vlib_frame_queues[index];
+ ASSERT (fq);
+ nelts = fq->nelts;
- while (n_left)
+retry:
+ tail = __atomic_load_n (&fq->tail, __ATOMIC_ACQUIRE);
+ new_tail = tail + 1;
+
+ if (new_tail >= fq->head + nelts)
{
- next_thread_index = thread_indices[0];
+ if (dont_wait)
+ return 0;
- if (next_thread_index != current_thread_index)
- {
- if (drop_on_congestion &&
- is_vlib_frame_queue_congested (
- frame_queue_index, next_thread_index, fqm->queue_hi_thresh,
- ptd->congested_handoff_queue_by_thread_index))
- {
- dbi[0] = buffer_indices[0];
- dbi++;
- n_drop++;
- goto next;
- }
-
- if (hf)
- hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_thread;
-
- hf = vlib_get_worker_handoff_queue_elt (
- frame_queue_index, next_thread_index,
- ptd->handoff_queue_elt_by_thread_index);
-
- n_left_to_next_thread = VLIB_FRAME_SIZE - hf->n_vectors;
- to_next_thread = &hf->buffer_index[hf->n_vectors];
- current_thread_index = next_thread_index;
- }
-
- to_next_thread[0] = buffer_indices[0];
- to_next_thread++;
- n_left_to_next_thread--;
-
- if (n_left_to_next_thread == 0)
- {
- hf->n_vectors = VLIB_FRAME_SIZE;
- vlib_put_frame_queue_elt (hf);
- vlib_get_main_by_index (current_thread_index)->check_frame_queues =
- 1;
- current_thread_index = ~0;
- ptd->handoff_queue_elt_by_thread_index[next_thread_index] = 0;
- hf = 0;
- }
-
- /* next */
- next:
- thread_indices += 1;
- buffer_indices += 1;
- n_left -= 1;
+ /* Wait until a ring slot is available */
+ while (new_tail >= fq->head + nelts)
+ vlib_worker_thread_barrier_check ();
}
- if (hf)
- hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_thread;
+ if (!__atomic_compare_exchange_n (&fq->tail, &tail, new_tail, 0 /* weak */,
+ __ATOMIC_RELAXED, __ATOMIC_RELAXED))
+ goto retry;
- /* Ship frames to the thread nodes */
- for (i = 0; i < vec_len (ptd->handoff_queue_elt_by_thread_index); i++)
+ return fq->elts + (new_tail & (nelts - 1));
+}
+
+static_always_inline u32
+vlib_buffer_enqueue_to_thread_inline (vlib_main_t *vm,
+ vlib_node_runtime_t *node,
+ vlib_frame_queue_main_t *fqm,
+ u32 *buffer_indices, u16 *thread_indices,
+ u32 n_packets, int drop_on_congestion)
+{
+ u32 drop_list[VLIB_FRAME_SIZE], n_drop = 0;
+ u64 used_elts[VLIB_FRAME_SIZE / 64] = {};
+ u64 mask[VLIB_FRAME_SIZE / 64];
+ vlib_frame_queue_elt_t *hf = 0;
+ u16 thread_index;
+ u32 n_comp, off = 0, n_left = n_packets;
+
+ thread_index = thread_indices[0];
+
+more:
+ clib_mask_compare_u16 (thread_index, thread_indices, mask, n_packets);
+ hf = vlib_get_frame_queue_elt (fqm, thread_index, drop_on_congestion);
+
+ n_comp = clib_compress_u32 (hf ? hf->buffer_index : drop_list + n_drop,
+ buffer_indices, mask, n_packets);
+
+ if (hf)
{
- if (ptd->handoff_queue_elt_by_thread_index[i])
+ if (node->flags & VLIB_NODE_FLAG_TRACE)
+ hf->maybe_trace = 1;
+ hf->n_vectors = n_comp;
+ __atomic_store_n (&hf->valid, 1, __ATOMIC_RELEASE);
+ vlib_get_main_by_index (thread_index)->check_frame_queues = 1;
+ }
+ else
+ n_drop += n_comp;
+
+ n_left -= n_comp;
+
+ if (n_left)
+ {
+ for (int i = 0; i < ARRAY_LEN (used_elts); i++)
+ used_elts[i] |= mask[i];
+
+ while (PREDICT_FALSE (used_elts[off] == ~0))
{
- hf = ptd->handoff_queue_elt_by_thread_index[i];
- /*
- * It works better to let the handoff node
- * rate-adapt, always ship the handoff queue element.
- */
- if (1 || hf->n_vectors == hf->last_n_vectors)
- {
- vlib_put_frame_queue_elt (hf);
- vlib_get_main_by_index (i)->check_frame_queues = 1;
- ptd->handoff_queue_elt_by_thread_index[i] = 0;
- }
- else
- hf->last_n_vectors = hf->n_vectors;
+ off++;
+ ASSERT (off < ARRAY_LEN (used_elts));
}
- ptd->congested_handoff_queue_by_thread_index[i] =
- (vlib_frame_queue_t *) (~0);
+
+ thread_index =
+ thread_indices[off * 64 + count_trailing_zeros (~used_elts[off])];
+ goto more;
}
if (drop_on_congestion && n_drop)
@@ -263,25 +257,50 @@
return n_packets - n_drop;
}
+u32 __clib_section (".vlib_buffer_enqueue_to_thread_fn")
+CLIB_MULTIARCH_FN (vlib_buffer_enqueue_to_thread_fn)
+(vlib_main_t *vm, vlib_node_runtime_t *node, u32 frame_queue_index,
+ u32 *buffer_indices, u16 *thread_indices, u32 n_packets,
+ int drop_on_congestion)
+{
+ vlib_thread_main_t *tm = vlib_get_thread_main ();
+ vlib_frame_queue_main_t *fqm;
+ u32 n_enq = 0;
+
+ fqm = vec_elt_at_index (tm->frame_queue_mains, frame_queue_index);
+
+ while (n_packets >= VLIB_FRAME_SIZE)
+ {
+ n_enq += vlib_buffer_enqueue_to_thread_inline (
+ vm, node, fqm, buffer_indices, thread_indices, VLIB_FRAME_SIZE,
+ drop_on_congestion);
+ buffer_indices += VLIB_FRAME_SIZE;
+ thread_indices += VLIB_FRAME_SIZE;
+ n_packets -= VLIB_FRAME_SIZE;
+ }
+
+ if (n_packets == 0)
+ return n_enq;
+
+ n_enq += vlib_buffer_enqueue_to_thread_inline (vm, node, fqm, buffer_indices,
+ thread_indices, n_packets,
+ drop_on_congestion);
+
+ return n_enq;
+}
+
CLIB_MARCH_FN_REGISTRATION (vlib_buffer_enqueue_to_thread_fn);
-/*
- * Check the frame queue to see if any frames are available.
- * If so, pull the packets off the frames and put them to
- * the handoff node.
- */
u32 __clib_section (".vlib_frame_queue_dequeue_fn")
CLIB_MULTIARCH_FN (vlib_frame_queue_dequeue_fn)
(vlib_main_t *vm, vlib_frame_queue_main_t *fqm)
{
u32 thread_id = vm->thread_index;
vlib_frame_queue_t *fq = fqm->vlib_frame_queues[thread_id];
+ u32 mask = fq->nelts - 1;
vlib_frame_queue_elt_t *elt;
- u32 *from, *to;
- vlib_frame_t *f;
- int msg_type;
- int processed = 0;
- u32 vectors = 0;
+ u32 n_free, n_copy, *from, *to = 0, processed = 0, vectors = 0;
+ vlib_frame_t *f = 0;
ASSERT (fq);
ASSERT (vm == vlib_global_main.vlib_mains[thread_id]);
@@ -301,7 +320,6 @@
fqt->nelts = fq->nelts;
fqt->head = fq->head;
- fqt->head_hint = fq->head_hint;
fqt->tail = fq->tail;
fqt->threshold = fq->vector_threshold;
fqt->n_in_use = fqt->tail - fqt->head;
@@ -318,7 +336,7 @@
/* Record a snapshot of the elements in use */
for (elix = 0; elix < fqt->nelts; elix++)
{
- elt = fq->elts + ((fq->head + 1 + elix) & (fq->nelts - 1));
+ elt = fq->elts + ((fq->head + 1 + elix) & (mask));
if (1 || elt->valid)
{
fqt->n_vectors[elix] = elt->n_vectors;
@@ -329,61 +347,71 @@
while (1)
{
- vlib_buffer_t *b;
if (fq->head == fq->tail)
+ break;
+
+ elt = fq->elts + ((fq->head + 1) & mask);
+
+ if (!__atomic_load_n (&elt->valid, __ATOMIC_ACQUIRE))
+ break;
+
+ from = elt->buffer_index + elt->offset;
+
+ ASSERT (elt->offset + elt->n_vectors <= VLIB_FRAME_SIZE);
+
+ if (f == 0)
{
- fq->head_hint = fq->head;
- return processed;
+ f = vlib_get_frame_to_node (vm, fqm->node_index);
+ to = vlib_frame_vector_args (f);
+ n_free = VLIB_FRAME_SIZE;
}
- elt = fq->elts + ((fq->head + 1) & (fq->nelts - 1));
-
- if (!elt->valid)
- {
- fq->head_hint = fq->head;
- return processed;
- }
-
- from = elt->buffer_index;
- msg_type = elt->msg_type;
-
- ASSERT (msg_type == VLIB_FRAME_QUEUE_ELT_DISPATCH_FRAME);
- ASSERT (elt->n_vectors <= VLIB_FRAME_SIZE);
-
- f = vlib_get_frame_to_node (vm, fqm->node_index);
-
- /* If the first vector is traced, set the frame trace flag */
- b = vlib_get_buffer (vm, from[0]);
- if (b->flags & VLIB_BUFFER_IS_TRACED)
+ if (elt->maybe_trace)
f->frame_flags |= VLIB_NODE_FLAG_TRACE;
- to = vlib_frame_vector_args (f);
+ n_copy = clib_min (n_free, elt->n_vectors);
- vlib_buffer_copy_indices (to, from, elt->n_vectors);
+ vlib_buffer_copy_indices (to, from, n_copy);
+ to += n_copy;
+ n_free -= n_copy;
+ vectors += n_copy;
- vectors += elt->n_vectors;
- f->n_vectors = elt->n_vectors;
- vlib_put_frame_to_node (vm, fqm->node_index, f);
-
- elt->valid = 0;
- elt->n_vectors = 0;
- elt->msg_type = 0xfefefefe;
- CLIB_MEMORY_BARRIER ();
- fq->head++;
- processed++;
-
- /*
- * Limit the number of packets pushed into the graph
- */
- if (vectors >= fq->vector_threshold)
+ if (n_free == 0)
{
- fq->head_hint = fq->head;
- return processed;
+ f->n_vectors = VLIB_FRAME_SIZE;
+ vlib_put_frame_to_node (vm, fqm->node_index, f);
+ f = 0;
}
+
+ if (n_copy < elt->n_vectors)
+ {
+ /* not empty - leave it on the ring */
+ elt->n_vectors -= n_copy;
+ elt->offset += n_copy;
+ }
+ else
+ {
+ /* empty - reset and bump head */
+ u32 sz = STRUCT_OFFSET_OF (vlib_frame_queue_elt_t, end_of_reset);
+ clib_memset (elt, 0, sz);
+ __atomic_store_n (&fq->head, fq->head + 1, __ATOMIC_RELEASE);
+ processed++;
+ }
+
+ /* Limit the number of packets pushed into the graph */
+ if (vectors >= fq->vector_threshold)
+ break;
}
- ASSERT (0);
+
+ if (f)
+ {
+ f->n_vectors = VLIB_FRAME_SIZE - n_free;
+ vlib_put_frame_to_node (vm, fqm->node_index, f);
+ }
+
return processed;
}
+
CLIB_MARCH_FN_REGISTRATION (vlib_frame_queue_dequeue_fn);
#ifndef CLIB_MARCH_VARIANT