Current virtio_dev_merge_rx() implementation just looks like the
old rte_vhost_dequeue_burst(), full of twisted logic, that you
can see same code block in quite many different places.
However, the logic of virtio_dev_merge_rx() is quite similar to
virtio_dev_rx(). The big difference is that the mergeable one
could allocate more than one available entries to hold the data.
Fetching all available entries to vec_buf at once makes the
difference a bit bigger then.
Anyway, it could be simpler, just like what we did for virtio_dev_rx().
One difference is that we need to update used ring properly.
The pseudo code looks like below:
while (1) {
if (this_desc_has_no_room) {
this_desc = fetch_next_from_vec_buf();
if (it is the last of a desc chain) {
update_used_ring();
}
}
if (this_mbuf_has_drained_totally) {
this_mbuf = fetch_next_mbuf();
if (this_mbuf == NULL)
break;
}
COPY(this_desc, this_mbuf);
}
This patch reduces quite many lines of code, therefore, make it much
more readable.
Signed-off-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
---
lib/librte_vhost/vhost_rxtx.c | 390 ++++++++++++++++++------------------------
1 file changed, 163 insertions(+), 227 deletions(-)
diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index d3775ad..3909584 100644
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -280,237 +280,200 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
return count;
}
-static inline uint32_t __attribute__((always_inline))
-copy_from_mbuf_to_vring(struct virtio_net *dev, uint32_t queue_id,
- uint16_t res_base_idx, uint16_t res_end_idx,
- struct rte_mbuf *pkt)
+static inline int
+fill_vec_buf(struct vhost_virtqueue *vq, uint32_t avail_idx,
+ uint32_t *allocated, uint32_t *vec_idx)
{
- uint32_t vec_idx = 0;
- uint32_t entry_success = 0;
- struct vhost_virtqueue *vq;
- /* The virtio_hdr is initialised to 0. */
- struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {
- {0, 0, 0, 0, 0, 0}, 0};
- uint16_t cur_idx = res_base_idx;
- uint64_t vb_addr = 0;
- uint64_t vb_hdr_addr = 0;
- uint32_t seg_offset = 0;
- uint32_t vb_offset = 0;
- uint32_t seg_avail;
- uint32_t vb_avail;
- uint32_t cpy_len, entry_len;
-
- if (pkt == NULL)
- return 0;
+ uint16_t idx = vq->avail->ring[avail_idx & (vq->size - 1)];
+ uint32_t vec_id = *vec_idx;
+ uint32_t len = *allocated;
- LOG_DEBUG(VHOST_DATA, "(%"PRIu64") Current Index %d| "
- "End Index %d\n",
- dev->device_fh, cur_idx, res_end_idx);
+ while (1) {
+ if (vec_id >= BUF_VECTOR_MAX)
+ return -1;
- /*
- * Convert from gpa to vva
- * (guest physical addr -> vhost virtual addr)
- */
- vq = dev->virtqueue[queue_id];
+ len += vq->desc[idx].len;
+ vq->buf_vec[vec_id].buf_addr = vq->desc[idx].addr;
+ vq->buf_vec[vec_id].buf_len = vq->desc[idx].len;
+ vq->buf_vec[vec_id].desc_idx = idx;
+ vec_id++;
- vb_addr = gpa_to_vva(dev, vq->buf_vec[vec_idx].buf_addr);
- vb_hdr_addr = vb_addr;
+ if ((vq->desc[idx].flags & VRING_DESC_F_NEXT) == 0)
+ break;
- /* Prefetch buffer address. */
- rte_prefetch0((void *)(uintptr_t)vb_addr);
+ idx = vq->desc[idx].next;
+ }
- virtio_hdr.num_buffers = res_end_idx - res_base_idx;
+ *allocated = len;
+ *vec_idx = vec_id;
- LOG_DEBUG(VHOST_DATA, "(%"PRIu64") RX: Num merge buffers %d\n",
- dev->device_fh, virtio_hdr.num_buffers);
+ return 0;
+}
- virtio_enqueue_offload(pkt, &virtio_hdr.hdr);
+/*
+ * As many data cores may want to access available buffers concurrently,
+ * they need to be reserved.
+ *
+ * Returns -1 on fail, 0 on success
+ */
+static inline int
+reserve_avail_buf_mergeable(struct vhost_virtqueue *vq, uint32_t size,
+ uint16_t *start, uint16_t *end)
+{
+ uint16_t res_start_idx;
+ uint16_t res_cur_idx;
+ uint16_t avail_idx;
+ uint32_t allocated;
+ uint32_t vec_idx;
+ uint16_t tries;
- rte_memcpy((void *)(uintptr_t)vb_hdr_addr,
- (const void *)&virtio_hdr, vq->vhost_hlen);
+again:
+ res_start_idx = vq->last_used_idx_res;
+ res_cur_idx = res_start_idx;
- PRINT_PACKET(dev, (uintptr_t)vb_hdr_addr, vq->vhost_hlen, 1);
+ allocated = 0;
+ vec_idx = 0;
+ tries = 0;
+ while (1) {
+ avail_idx = *((volatile uint16_t *)&vq->avail->idx);
+ if (unlikely(res_cur_idx == avail_idx)) {
+ LOG_DEBUG(VHOST_DATA, "(%"PRIu64") Failed "
+ "to get enough desc from vring\n",
+ dev->device_fh);
+ return -1;
+ }
- seg_avail = rte_pktmbuf_data_len(pkt);
- vb_offset = vq->vhost_hlen;
- vb_avail = vq->buf_vec[vec_idx].buf_len - vq->vhost_hlen;
+ if (fill_vec_buf(vq, res_cur_idx, &allocated, &vec_idx) < 0)
+ return -1;
- entry_len = vq->vhost_hlen;
+ res_cur_idx++;
+ tries++;
- if (vb_avail == 0) {
- uint32_t desc_idx =
- vq->buf_vec[vec_idx].desc_idx;
+ if (allocated >= size)
+ break;
- if ((vq->desc[desc_idx].flags
- & VRING_DESC_F_NEXT) == 0) {
- /* Update used ring with desc information */
- vq->used->ring[cur_idx & (vq->size - 1)].id
- = vq->buf_vec[vec_idx].desc_idx;
- vq->used->ring[cur_idx & (vq->size - 1)].len
- = entry_len;
+ /*
+ * if we tried all available ring items, and still
+ * can't get enough buf, it means something abnormal
+ * happened.
+ */
+ if (tries >= vq->size)
+ return -1;
+ }
- entry_len = 0;
- cur_idx++;
- entry_success++;
- }
+ /*
+ * update vq->last_used_idx_res atomically.
+ * retry again if failed.
+ */
+ if (rte_atomic16_cmpset(&vq->last_used_idx_res,
+ res_start_idx, res_cur_idx) == 0)
+ goto again;
- vec_idx++;
- vb_addr = gpa_to_vva(dev, vq->buf_vec[vec_idx].buf_addr);
+ *start = res_start_idx;
+ *end = res_cur_idx;
+ return 0;
+}
- /* Prefetch buffer address. */
- rte_prefetch0((void *)(uintptr_t)vb_addr);
- vb_offset = 0;
- vb_avail = vq->buf_vec[vec_idx].buf_len;
- }
+static inline uint32_t __attribute__((always_inline))
+copy_mbuf_to_desc_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
+ uint16_t res_start_idx, uint16_t res_end_idx,
+ struct rte_mbuf *m)
+{
+ struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, 0, 0, 0, 0, 0}, 0};
+ uint32_t vec_idx = 0;
+ uint16_t cur_idx = res_start_idx;
+ uint64_t desc_addr;
+ uint32_t mbuf_offset, mbuf_avail;
+ uint32_t desc_offset, desc_avail;
+ uint32_t cpy_len;
+ uint16_t desc_idx, used_idx;
+ uint32_t nr_used = 0;
- cpy_len = RTE_MIN(vb_avail, seg_avail);
+ if (m == NULL)
+ return 0;
- while (cpy_len > 0) {
- /* Copy mbuf data to vring buffer */
- rte_memcpy((void *)(uintptr_t)(vb_addr + vb_offset),
- rte_pktmbuf_mtod_offset(pkt, const void *, seg_offset),
- cpy_len);
+ LOG_DEBUG(VHOST_DATA,
+ "(%"PRIu64") Current Index %d| End Index %d\n",
+ dev->device_fh, cur_idx, res_end_idx);
- PRINT_PACKET(dev,
- (uintptr_t)(vb_addr + vb_offset),
- cpy_len, 0);
+ desc_addr = gpa_to_vva(dev, vq->buf_vec[vec_idx].buf_addr);
+ rte_prefetch0((void *)(uintptr_t)desc_addr);
+
+ virtio_hdr.num_buffers = res_end_idx - res_start_idx;
+ LOG_DEBUG(VHOST_DATA, "(%"PRIu64") RX: Num merge buffers %d\n",
+ dev->device_fh, virtio_hdr.num_buffers);
- seg_offset += cpy_len;
- vb_offset += cpy_len;
- seg_avail -= cpy_len;
- vb_avail -= cpy_len;
- entry_len += cpy_len;
-
- if (seg_avail != 0) {
- /*
- * The virtio buffer in this vring
- * entry reach to its end.
- * But the segment doesn't complete.
- */
- if ((vq->desc[vq->buf_vec[vec_idx].desc_idx].flags &
- VRING_DESC_F_NEXT) == 0) {
+ virtio_enqueue_offload(m, &virtio_hdr.hdr);
+ rte_memcpy((void *)(uintptr_t)desc_addr,
+ (const void *)&virtio_hdr, vq->vhost_hlen);
+ PRINT_PACKET(dev, (uintptr_t)desc_addr, vq->vhost_hlen, 0);
+
+ desc_avail = vq->buf_vec[vec_idx].buf_len - vq->vhost_hlen;
+ desc_offset = vq->vhost_hlen;
+
+ mbuf_avail = rte_pktmbuf_data_len(m);
+ mbuf_offset = 0;
+ while (1) {
+ /* done with current desc buf, get the next one */
+ if (desc_avail == 0) {
+ desc_idx = vq->buf_vec[vec_idx].desc_idx;
+
+ if ((vq->desc[desc_idx].flags & VRING_DESC_F_NEXT) ==
0) {
/* Update used ring with desc information */
- vq->used->ring[cur_idx & (vq->size - 1)].id
- = vq->buf_vec[vec_idx].desc_idx;
- vq->used->ring[cur_idx & (vq->size - 1)].len
- = entry_len;
- entry_len = 0;
- cur_idx++;
- entry_success++;
+ used_idx = cur_idx++ & (vq->size - 1);
+ vq->used->ring[used_idx].id = desc_idx;
+ vq->used->ring[used_idx].len = desc_offset;
+
+ nr_used++;
}
vec_idx++;
- vb_addr = gpa_to_vva(dev,
- vq->buf_vec[vec_idx].buf_addr);
- vb_offset = 0;
- vb_avail = vq->buf_vec[vec_idx].buf_len;
- cpy_len = RTE_MIN(vb_avail, seg_avail);
- } else {
- /*
- * This current segment complete, need continue to
- * check if the whole packet complete or not.
- */
- pkt = pkt->next;
- if (pkt != NULL) {
- /*
- * There are more segments.
- */
- if (vb_avail == 0) {
- /*
- * This current buffer from vring is
- * used up, need fetch next buffer
- * from buf_vec.
- */
- uint32_t desc_idx =
- vq->buf_vec[vec_idx].desc_idx;
-
- if ((vq->desc[desc_idx].flags &
- VRING_DESC_F_NEXT) == 0) {
- uint16_t wrapped_idx =
- cur_idx & (vq->size -
1);
- /*
- * Update used ring with the
- * descriptor information
- */
- vq->used->ring[wrapped_idx].id
- = desc_idx;
- vq->used->ring[wrapped_idx].len
- = entry_len;
- entry_success++;
- entry_len = 0;
- cur_idx++;
- }
-
- /* Get next buffer from buf_vec. */
- vec_idx++;
- vb_addr = gpa_to_vva(dev,
- vq->buf_vec[vec_idx].buf_addr);
- vb_avail =
- vq->buf_vec[vec_idx].buf_len;
- vb_offset = 0;
- }
-
- seg_offset = 0;
- seg_avail = rte_pktmbuf_data_len(pkt);
- cpy_len = RTE_MIN(vb_avail, seg_avail);
- } else {
- /*
- * This whole packet completes.
- */
- /* Update used ring with desc information */
- vq->used->ring[cur_idx & (vq->size - 1)].id
- = vq->buf_vec[vec_idx].desc_idx;
- vq->used->ring[cur_idx & (vq->size - 1)].len
- = entry_len;
- entry_success++;
- break;
- }
+ desc_addr = gpa_to_vva(dev,
vq->buf_vec[vec_idx].buf_addr);
+
+ /* Prefetch buffer address. */
+ rte_prefetch0((void *)(uintptr_t)desc_addr);
+ desc_offset = 0;
+ desc_avail = vq->buf_vec[vec_idx].buf_len;
}
- }
- return entry_success;
-}
+ /* done with current mbuf, get the next one */
+ if (mbuf_avail == 0) {
+ m = m->next;
+ if (!m)
+ break;
-static inline void __attribute__((always_inline))
-update_secure_len(struct vhost_virtqueue *vq, uint32_t id,
- uint32_t *secure_len, uint32_t *vec_idx)
-{
- uint16_t wrapped_idx = id & (vq->size - 1);
- uint32_t idx = vq->avail->ring[wrapped_idx];
- uint8_t next_desc;
- uint32_t len = *secure_len;
- uint32_t vec_id = *vec_idx;
+ mbuf_offset = 0;
+ mbuf_avail = rte_pktmbuf_data_len(m);
+ }
- do {
- next_desc = 0;
- len += vq->desc[idx].len;
- vq->buf_vec[vec_id].buf_addr = vq->desc[idx].addr;
- vq->buf_vec[vec_id].buf_len = vq->desc[idx].len;
- vq->buf_vec[vec_id].desc_idx = idx;
- vec_id++;
+ cpy_len = RTE_MIN(desc_avail, mbuf_avail);
+ rte_memcpy((void *)((uintptr_t)(desc_addr + desc_offset)),
+ rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
+ cpy_len);
+ PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset),
+ cpy_len, 0);
- if (vq->desc[idx].flags & VRING_DESC_F_NEXT) {
- idx = vq->desc[idx].next;
- next_desc = 1;
- }
- } while (next_desc);
+ mbuf_avail -= cpy_len;
+ mbuf_offset += cpy_len;
+ desc_avail -= cpy_len;
+ desc_offset += cpy_len;
+ }
+
+ used_idx = cur_idx & (vq->size - 1);
+ vq->used->ring[used_idx].id = vq->buf_vec[vec_idx].desc_idx;
+ vq->used->ring[used_idx].len = desc_offset;
+ nr_used++;
- *secure_len = len;
- *vec_idx = vec_id;
+ return nr_used;
}
-/*
- * This function works for mergeable RX.
- */
static inline uint32_t __attribute__((always_inline))
virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
struct rte_mbuf **pkts, uint32_t count)
{
struct vhost_virtqueue *vq;
- uint32_t pkt_idx = 0, entry_success = 0;
- uint16_t avail_idx;
- uint16_t res_base_idx, res_cur_idx;
- uint8_t success = 0;
+ uint32_t pkt_idx = 0, nr_used = 0;
+ uint16_t start, end;
LOG_DEBUG(VHOST_DATA, "(%"PRIu64") virtio_dev_merge_rx()\n",
dev->device_fh);
@@ -526,57 +489,30 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t
queue_id,
return 0;
count = RTE_MIN((uint32_t)MAX_PKT_BURST, count);
-
if (count == 0)
return 0;
for (pkt_idx = 0; pkt_idx < count; pkt_idx++) {
uint32_t pkt_len = pkts[pkt_idx]->pkt_len + vq->vhost_hlen;
- do {
- /*
- * As many data cores may want access to available
- * buffers, they need to be reserved.
- */
- uint32_t secure_len = 0;
- uint32_t vec_idx = 0;
-
- res_base_idx = vq->last_used_idx_res;
- res_cur_idx = res_base_idx;
-
- do {
- avail_idx = *((volatile uint16_t
*)&vq->avail->idx);
- if (unlikely(res_cur_idx == avail_idx))
- goto merge_rx_exit;
-
- update_secure_len(vq, res_cur_idx,
- &secure_len, &vec_idx);
- res_cur_idx++;
- } while (pkt_len > secure_len);
-
- /* vq->last_used_idx_res is atomically updated. */
- success = rte_atomic16_cmpset(&vq->last_used_idx_res,
- res_base_idx,
- res_cur_idx);
- } while (success == 0);
-
- entry_success = copy_from_mbuf_to_vring(dev, queue_id,
- res_base_idx, res_cur_idx, pkts[pkt_idx]);
+ if (reserve_avail_buf_mergeable(vq, pkt_len, &start, &end) < 0)
+ break;
+ nr_used = copy_mbuf_to_desc_mergeable(dev, vq, start, end,
+ pkts[pkt_idx]);
rte_compiler_barrier();
/*
* Wait until it's our turn to add our buffer
* to the used ring.
*/
- while (unlikely(vq->last_used_idx != res_base_idx))
+ while (unlikely(vq->last_used_idx != start))
rte_pause();
- *(volatile uint16_t *)&vq->used->idx += entry_success;
- vq->last_used_idx = res_cur_idx;
+ *(volatile uint16_t *)&vq->used->idx += nr_used;
+ vq->last_used_idx = end;
}
-merge_rx_exit:
if (likely(pkt_idx)) {
/* flush used->idx update before we read avail->flags. */
rte_mb();
--
1.9.0
