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nsim: limit tx burst size and refactor input node

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Type: improvement

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: Ic93a598051d437a5801d794b678edf6e73d42a47
This commit is contained in:
Florin Coras
2020-07-31 13:56:40 -07:00
parent e6c3e8f0ee
commit 9811007f5f
2 changed files with 27 additions and 61 deletions
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2
src/plugins/nsim/nsim.h
View File

@@ -25,6 +25,8 @@
#include <vppinfra/hash.h>
#include <vppinfra/error.h>
#define NSIM_MAX_TX_BURST 32 /**< max packets in a tx burst */
typedef struct
{
f64 tx_time;

86
src/plugins/nsim/nsim_input.c
View File

@@ -71,15 +71,9 @@ nsim_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
vlib_frame_t * f, int is_trace)
{
nsim_main_t *nsm = &nsim_main;
u32 my_thread_index = vm->thread_index;
nsim_wheel_t *wp = nsm->wheel_by_thread[my_thread_index];
f64 now = vlib_time_now (vm);
uword n_tx_packets = 0;
u32 bi0, next0;
u32 *to_next;
u32 next_index;
u32 n_left_to_next;
nsim_wheel_t *wp = nsm->wheel_by_thread[vm->thread_index];
nsim_wheel_entry_t *ep;
f64 now;
/* Nothing on the scheduler wheel? */
if (wp->cursize == 0)
@@ -87,67 +81,37 @@ nsim_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
/* First entry on the wheel isn't expired? */
ep = wp->entries + wp->head;
now = vlib_time_now (vm);
if (ep->tx_time > now)
return n_tx_packets;
return 0;
next_index = node->cached_next_index;
u32 n_burst = clib_min (wp->cursize, NSIM_MAX_TX_BURST), n_tx_packets = 0;
u32 froms[NSIM_MAX_TX_BURST], *from;
u16 nexts[NSIM_MAX_TX_BURST], *next;
/* Be aware: this is not the usual coding pattern */
while (wp->cursize && ep->tx_time <= now)
from = froms;
next = nexts;
while (n_tx_packets < n_burst && ep->tx_time <= now)
{
vlib_buffer_t *b0;
/* prefetch one line / 2 entries ahead */
if ((((uword) ep) & (CLIB_CACHE_LINE_BYTES - 1)) == 0)
CLIB_PREFETCH ((ep + 2), CLIB_CACHE_LINE_BYTES, LOAD);
vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
ep = wp->entries + wp->head;
from[0] = ep->buffer_index;
next[0] = ep->output_next_index;
while (n_left_to_next > 0)
{
/* prefetch one line / 2 entries ahead */
if ((((uword) ep) & (CLIB_CACHE_LINE_BYTES - 1)) == 0)
CLIB_PREFETCH ((ep + 2), CLIB_CACHE_LINE_BYTES, LOAD);
/* Pick up buffer from the wheel */
bi0 = ep->buffer_index;
wp->head++;
if (wp->head == wp->wheel_size)
wp->head = 0;
to_next[0] = bi0;
to_next += 1;
n_left_to_next -= 1;
next0 = ep->output_next_index;
/* verify speculative enqueue, maybe switch current next frame */
vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
to_next, n_left_to_next,
bi0, next0);
/* Advance to the next ring entry */
wp->head++;
if (wp->head == wp->wheel_size)
wp->head = 0;
wp->cursize--;
ep = wp->entries + wp->head;
n_tx_packets++;
if (is_trace)
{
b0 = vlib_get_buffer (vm, bi0);
if (b0->flags & VLIB_BUFFER_IS_TRACED)
{
nsim_tx_trace_t *t =
vlib_add_trace (vm, node, b0, sizeof (*t));
t->expired = now;
t->next_index = next0;
}
}
/* Out of ring entries? */
if (PREDICT_FALSE (wp->cursize == 0))
break;
}
vlib_put_next_frame (vm, node, next_index, n_left_to_next);
/* If the current entry hasn't expired, we're done */
if (ep->tx_time > now)
break;
from += 1;
next += 1;
n_tx_packets++;
}
wp->cursize -= n_tx_packets;
vlib_buffer_enqueue_to_next (vm, node, froms, nexts, n_tx_packets);
vlib_node_increment_counter (vm, node->node_index,
NSIM_TX_ERROR_TRANSMITTED, n_tx_packets);
return n_tx_packets;