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vhost: Cache qsz_mask instead of qsz in vhost_user_vring_t

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In the data path, we grab qsz from vhost_user_vring_t to compute
qsz_mask and store it in a stack variable to use on many occasions.
We never use qsz for any meaningful purpose. It is more useful to
cache qsz_mask in vhost_user_vring_t to avoid the needless computation
in the data path.

Change-Id: Idf4d94a9754d5c75c899f1f4f59602275b9904a6
Signed-off-by: Steven <sluong@cisco.com>
This commit is contained in:
Steven
2017-08-29 09:23:26 -07:00
committed by Florin Coras
parent a894434e30
commit 978788903b
2 changed files with 28 additions and 32 deletions
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58
src/vnet/devices/virtio/vhost-user.c
View File

@ -854,7 +854,7 @@ vhost_user_socket_read (unix_file_t * uf)
(msg.state.num == 0) || /* it cannot be zero */
((msg.state.num - 1) & msg.state.num)) /* must be power of 2 */
goto close_socket;
vui->vrings[msg.state.index].qsz = msg.state.num;
vui->vrings[msg.state.index].qsz_mask = msg.state.num - 1;
break;
case VHOST_USER_SET_VRING_ADDR:
@ -1288,9 +1288,8 @@ vhost_user_rx_trace (vhost_trace_t * t,
vlib_buffer_t * b, vhost_user_vring_t * txvq)
{
vhost_user_main_t *vum = &vhost_user_main;
u32 qsz_mask = txvq->qsz - 1;
u32 last_avail_idx = txvq->last_avail_idx;
u32 desc_current = txvq->avail->ring[last_avail_idx & qsz_mask];
u32 desc_current = txvq->avail->ring[last_avail_idx & txvq->qsz_mask];
vring_desc_t *hdr_desc = 0;
virtio_net_hdr_mrg_rxbuf_t *hdr;
u32 hint = 0;
@ -1409,19 +1408,19 @@ vhost_user_rx_discard_packet (vlib_main_t * vm,
*/
u32 discarded_packets = 0;
u32 avail_idx = txvq->avail->idx;
u16 qsz_mask = txvq->qsz - 1;
while (discarded_packets != discard_max)
{
if (avail_idx == txvq->last_avail_idx)
goto out;
u16 desc_chain_head =
txvq->avail->ring[txvq->last_avail_idx & qsz_mask];
txvq->avail->ring[txvq->last_avail_idx & txvq->qsz_mask];
txvq->last_avail_idx++;
txvq->used->ring[txvq->last_used_idx & qsz_mask].id = desc_chain_head;
txvq->used->ring[txvq->last_used_idx & qsz_mask].len = 0;
txvq->used->ring[txvq->last_used_idx & txvq->qsz_mask].id =
desc_chain_head;
txvq->used->ring[txvq->last_used_idx & txvq->qsz_mask].len = 0;
vhost_user_log_dirty_ring (vui, txvq,
ring[txvq->last_used_idx & qsz_mask]);
ring[txvq->last_used_idx & txvq->qsz_mask]);
txvq->last_used_idx++;
discarded_packets++;
}
@ -1469,7 +1468,6 @@ vhost_user_if_input (vlib_main_t * vm,
u32 n_left_to_next, *to_next;
u32 next_index = VNET_DEVICE_INPUT_NEXT_ETHERNET_INPUT;
u32 n_trace = vlib_get_trace_count (vm, node);
u16 qsz_mask;
u32 map_hint = 0;
u16 thread_index = vlib_get_thread_index ();
u16 copy_len = 0;
@ -1529,7 +1527,7 @@ vhost_user_if_input (vlib_main_t * vm,
return 0;
}
if (PREDICT_FALSE (n_left == txvq->qsz))
if (PREDICT_FALSE (n_left == (txvq->qsz_mask + 1)))
{
/*
* Informational error logging when VPP is not
@ -1539,8 +1537,6 @@ vhost_user_if_input (vlib_main_t * vm,
VHOST_USER_INPUT_FUNC_ERROR_FULL_RX_QUEUE, 1);
}
qsz_mask = txvq->qsz - 1;
if (n_left > VLIB_FRAME_SIZE)
n_left = VLIB_FRAME_SIZE;
@ -1605,7 +1601,8 @@ vhost_user_if_input (vlib_main_t * vm,
break;
}
desc_current = txvq->avail->ring[txvq->last_avail_idx & qsz_mask];
desc_current =
txvq->avail->ring[txvq->last_avail_idx & txvq->qsz_mask];
vum->cpus[thread_index].rx_buffers_len--;
bi_current = (vum->cpus[thread_index].rx_buffers)
[vum->cpus[thread_index].rx_buffers_len];
@ -1621,10 +1618,12 @@ vhost_user_if_input (vlib_main_t * vm,
rx_buffers_len - 1], LOAD);
/* Just preset the used descriptor id and length for later */
txvq->used->ring[txvq->last_used_idx & qsz_mask].id = desc_current;
txvq->used->ring[txvq->last_used_idx & qsz_mask].len = 0;
txvq->used->ring[txvq->last_used_idx & txvq->qsz_mask].id =
desc_current;
txvq->used->ring[txvq->last_used_idx & txvq->qsz_mask].len = 0;
vhost_user_log_dirty_ring (vui, txvq,
ring[txvq->last_used_idx & qsz_mask]);
ring[txvq->last_used_idx &
txvq->qsz_mask]);
/* The buffer should already be initialized */
b_head->total_length_not_including_first_buffer = 0;
@ -1889,9 +1888,8 @@ vhost_user_tx_trace (vhost_trace_t * t,
vlib_buffer_t * b, vhost_user_vring_t * rxvq)
{
vhost_user_main_t *vum = &vhost_user_main;
u32 qsz_mask = rxvq->qsz - 1;
u32 last_avail_idx = rxvq->last_avail_idx;
u32 desc_current = rxvq->avail->ring[last_avail_idx & qsz_mask];
u32 desc_current = rxvq->avail->ring[last_avail_idx & rxvq->qsz_mask];
vring_desc_t *hdr_desc = 0;
u32 hint = 0;
@ -1979,7 +1977,6 @@ vhost_user_tx (vlib_main_t * vm,
pool_elt_at_index (vum->vhost_user_interfaces, rd->dev_instance);
u32 qid = ~0;
vhost_user_vring_t *rxvq;
u16 qsz_mask;
u8 error;
u32 thread_index = vlib_get_thread_index ();
u32 map_hint = 0;
@ -2006,8 +2003,6 @@ vhost_user_tx (vlib_main_t * vm,
if (PREDICT_FALSE (vui->use_tx_spinlock))
vhost_user_vring_lock (vui, qid);
qsz_mask = rxvq->qsz - 1; /* qsz is always power of 2 */
retry:
error = VHOST_USER_TX_FUNC_ERROR_NONE;
tx_headers_len = 0;
@ -2043,7 +2038,7 @@ retry:
desc_table = rxvq->desc;
desc_head = desc_index =
rxvq->avail->ring[rxvq->last_avail_idx & qsz_mask];
rxvq->avail->ring[rxvq->last_avail_idx & rxvq->qsz_mask];
/* Go deeper in case of indirect descriptor
* I don't know of any driver providing indirect for RX. */
@ -2108,13 +2103,13 @@ retry:
&vum->cpus[thread_index].tx_headers[tx_headers_len - 1];
//Move from available to used buffer
rxvq->used->ring[rxvq->last_used_idx & qsz_mask].id =
rxvq->used->ring[rxvq->last_used_idx & rxvq->qsz_mask].id =
desc_head;
rxvq->used->ring[rxvq->last_used_idx & qsz_mask].len =
rxvq->used->ring[rxvq->last_used_idx & rxvq->qsz_mask].len =
desc_len;
vhost_user_log_dirty_ring (vui, rxvq,
ring[rxvq->last_used_idx &
qsz_mask]);
rxvq->qsz_mask]);
rxvq->last_avail_idx++;
rxvq->last_used_idx++;
@ -2133,7 +2128,7 @@ retry:
desc_table = rxvq->desc;
desc_head = desc_index =
rxvq->avail->ring[rxvq->last_avail_idx & qsz_mask];
rxvq->avail->ring[rxvq->last_avail_idx & rxvq->qsz_mask];
if (PREDICT_FALSE
(rxvq->desc[desc_head].flags & VIRTQ_DESC_F_INDIRECT))
{
@ -2201,10 +2196,10 @@ retry:
}
//Move from available to used ring
rxvq->used->ring[rxvq->last_used_idx & qsz_mask].id = desc_head;
rxvq->used->ring[rxvq->last_used_idx & qsz_mask].len = desc_len;
rxvq->used->ring[rxvq->last_used_idx & rxvq->qsz_mask].id = desc_head;
rxvq->used->ring[rxvq->last_used_idx & rxvq->qsz_mask].len = desc_len;
vhost_user_log_dirty_ring (vui, rxvq,
ring[rxvq->last_used_idx & qsz_mask]);
ring[rxvq->last_used_idx & rxvq->qsz_mask]);
rxvq->last_avail_idx++;
rxvq->last_used_idx++;
@ -3263,7 +3258,8 @@ show_vhost_user_command_fn (vlib_main_t * vm,
vlib_cli_output (vm,
" qsz %d last_avail_idx %d last_used_idx %d\n",
vui->vrings[q].qsz, vui->vrings[q].last_avail_idx,
vui->vrings[q].qsz_mask + 1,
vui->vrings[q].last_avail_idx,
vui->vrings[q].last_used_idx);
if (vui->vrings[q].avail && vui->vrings[q].used)
@ -3286,7 +3282,7 @@ show_vhost_user_command_fn (vlib_main_t * vm,
" id addr len flags next user_addr\n");
vlib_cli_output (vm,
" ===== ================== ===== ====== ===== ==================\n");
for (j = 0; j < vui->vrings[q].qsz; j++)
for (j = 0; j < vui->vrings[q].qsz_mask + 1; j++)
{
u32 mem_hint = 0;
vlib_cli_output (vm,

2
src/vnet/devices/virtio/vhost-user.h
View File

@ -191,7 +191,7 @@ typedef struct vhost_user_msg {
typedef struct
{
CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
u16 qsz;
u16 qsz_mask;
u16 last_avail_idx;
u16 last_used_idx;
u16 n_since_last_int;