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authorYuanhan Liu <yuanhan.liu@linux.intel.com>2016-05-02 17:46:16 -0700
committerYuanhan Liu <yuanhan.liu@linux.intel.com>2016-06-22 09:47:12 +0200
commit7f74b95c444f617ac36c77253ade1bbb8dea4c88 (patch)
tree63828d2530c3efe234fe5622e7fa745180d64fa7 /lib/librte_vhost
parent39cac2adcad033bb24c79b84048083a54a494181 (diff)
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vhost: pre update used ring for Tx and Rx
Pre update and update used ring in batch for Tx and Rx at the stage while fetching all avail desc idx. This would reduce some cache misses and hence, increase the performance a bit. Pre update would be feasible as guest driver will not start processing those entries as far as we don't update "used->idx". (I'm not 100% certain I don't miss anything, though). Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com> Tested-by: Rich Lane <rich.lane@bigswitch.com>
Diffstat (limited to 'lib/librte_vhost')
-rw-r--r--lib/librte_vhost/vhost_rxtx.c58
1 files changed, 28 insertions, 30 deletions
diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index 96720db..52f87c1 100644
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -137,7 +137,7 @@ copy_virtio_net_hdr(struct virtio_net *dev, uint64_t desc_addr,
static inline int __attribute__((always_inline))
copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
- struct rte_mbuf *m, uint16_t desc_idx, uint32_t *copied)
+ struct rte_mbuf *m, uint16_t desc_idx)
{
uint32_t desc_avail, desc_offset;
uint32_t mbuf_avail, mbuf_offset;
@@ -161,7 +161,6 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
desc_offset = dev->vhost_hlen;
desc_avail = desc->len - dev->vhost_hlen;
- *copied = rte_pktmbuf_pkt_len(m);
mbuf_avail = rte_pktmbuf_data_len(m);
mbuf_offset = 0;
while (mbuf_avail != 0 || m->next != NULL) {
@@ -262,6 +261,7 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
struct vhost_virtqueue *vq;
uint16_t res_start_idx, res_end_idx;
uint16_t desc_indexes[MAX_PKT_BURST];
+ uint16_t used_idx;
uint32_t i;
LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
@@ -285,27 +285,29 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
/* Retrieve all of the desc indexes first to avoid caching issues. */
rte_prefetch0(&vq->avail->ring[res_start_idx & (vq->size - 1)]);
for (i = 0; i < count; i++) {
- desc_indexes[i] = vq->avail->ring[(res_start_idx + i) &
- (vq->size - 1)];
+ used_idx = (res_start_idx + i) & (vq->size - 1);
+ desc_indexes[i] = vq->avail->ring[used_idx];
+ vq->used->ring[used_idx].id = desc_indexes[i];
+ vq->used->ring[used_idx].len = pkts[i]->pkt_len +
+ dev->vhost_hlen;
+ vhost_log_used_vring(dev, vq,
+ offsetof(struct vring_used, ring[used_idx]),
+ sizeof(vq->used->ring[used_idx]));
}
rte_prefetch0(&vq->desc[desc_indexes[0]]);
for (i = 0; i < count; i++) {
uint16_t desc_idx = desc_indexes[i];
- uint16_t used_idx = (res_start_idx + i) & (vq->size - 1);
- uint32_t copied;
int err;
- err = copy_mbuf_to_desc(dev, vq, pkts[i], desc_idx, &copied);
-
- vq->used->ring[used_idx].id = desc_idx;
- if (unlikely(err))
+ err = copy_mbuf_to_desc(dev, vq, pkts[i], desc_idx);
+ if (unlikely(err)) {
+ used_idx = (res_start_idx + i) & (vq->size - 1);
vq->used->ring[used_idx].len = dev->vhost_hlen;
- else
- vq->used->ring[used_idx].len = copied + dev->vhost_hlen;
- vhost_log_used_vring(dev, vq,
- offsetof(struct vring_used, ring[used_idx]),
- sizeof(vq->used->ring[used_idx]));
+ vhost_log_used_vring(dev, vq,
+ offsetof(struct vring_used, ring[used_idx]),
+ sizeof(vq->used->ring[used_idx]));
+ }
if (i + 1 < count)
rte_prefetch0(&vq->desc[desc_indexes[i+1]]);
@@ -882,6 +884,7 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
/* Prefetch available ring to retrieve head indexes. */
used_idx = vq->last_used_idx & (vq->size - 1);
rte_prefetch0(&vq->avail->ring[used_idx]);
+ rte_prefetch0(&vq->used->ring[used_idx]);
count = RTE_MIN(count, MAX_PKT_BURST);
count = RTE_MIN(count, free_entries);
@@ -890,22 +893,23 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
/* Retrieve all of the head indexes first to avoid caching issues. */
for (i = 0; i < count; i++) {
- desc_indexes[i] = vq->avail->ring[(vq->last_used_idx + i) &
- (vq->size - 1)];
+ used_idx = (vq->last_used_idx + i) & (vq->size - 1);
+ desc_indexes[i] = vq->avail->ring[used_idx];
+
+ vq->used->ring[used_idx].id = desc_indexes[i];
+ vq->used->ring[used_idx].len = 0;
+ vhost_log_used_vring(dev, vq,
+ offsetof(struct vring_used, ring[used_idx]),
+ sizeof(vq->used->ring[used_idx]));
}
/* Prefetch descriptor index. */
rte_prefetch0(&vq->desc[desc_indexes[0]]);
- rte_prefetch0(&vq->used->ring[vq->last_used_idx & (vq->size - 1)]);
-
for (i = 0; i < count; i++) {
int err;
- if (likely(i + 1 < count)) {
+ if (likely(i + 1 < count))
rte_prefetch0(&vq->desc[desc_indexes[i + 1]]);
- rte_prefetch0(&vq->used->ring[(used_idx + 1) &
- (vq->size - 1)]);
- }
pkts[i] = rte_pktmbuf_alloc(mbuf_pool);
if (unlikely(pkts[i] == NULL)) {
@@ -919,18 +923,12 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
rte_pktmbuf_free(pkts[i]);
break;
}
-
- used_idx = vq->last_used_idx++ & (vq->size - 1);
- vq->used->ring[used_idx].id = desc_indexes[i];
- vq->used->ring[used_idx].len = 0;
- vhost_log_used_vring(dev, vq,
- offsetof(struct vring_used, ring[used_idx]),
- sizeof(vq->used->ring[used_idx]));
}
rte_smp_wmb();
rte_smp_rmb();
vq->used->idx += i;
+ vq->last_used_idx += i;
vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
sizeof(vq->used->idx));