This is a simple refactor, as there isn't any twisted logic in old
code. Here I just broke the code and introduced two helper functions,
reserve_avail_buf() and copy_mbuf_to_desc() to make the code more
readable.
It saves nearly 1K bytes of code size:
# without this patch
$ size /path/to/vhost_rxtx.o
text data bss dec hex filename
37435 0 0 37435 923b /path/to/vhost_rxtx.o
# with this patch
$ size /path/to/vhost_rxtx.o
text data bss dec hex filename
36539 0 0 36539 8ebb /path/to/vhost_rxtx.o
Signed-off-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
---
lib/librte_vhost/vhost_rxtx.c | 275 ++++++++++++++++++++----------------------
1 file changed, 129 insertions(+), 146 deletions(-)
diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index b4c6cab..cb29459 100644
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -61,6 +61,107 @@ is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t
qp_nb)
return (is_tx ^ (idx & 1)) == 0 && idx < qp_nb * VIRTIO_QNUM;
}
+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)
+{
+ uint32_t desc_avail, desc_offset;
+ uint32_t mbuf_avail, mbuf_offset;
+ uint32_t cpy_len;
+ struct vring_desc *desc;
+ uint64_t desc_addr;
+ struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, 0, 0, 0, 0, 0}, 0};
+
+ desc = &vq->desc[desc_idx];
+ desc_addr = gpa_to_vva(dev, desc->addr);
+ rte_prefetch0((void *)(uintptr_t)desc_addr);
+
+ 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_offset = vq->vhost_hlen;
+ desc_avail = desc->len - vq->vhost_hlen;
+
+ mbuf_avail = rte_pktmbuf_data_len(m);
+ mbuf_offset = 0;
+ while (1) {
+ /* done with current mbuf, fetch next */
+ if (mbuf_avail == 0) {
+ m = m->next;
+ if (m == NULL)
+ break;
+
+ mbuf_offset = 0;
+ mbuf_avail = rte_pktmbuf_data_len(m);
+ }
+
+ /* done with current desc buf, fetch next */
+ if (desc_avail == 0) {
+ if ((desc->flags & VRING_DESC_F_NEXT) == 0) {
+ /* Room in vring buffer is not enough */
+ return -1;
+ }
+
+ desc = &vq->desc[desc->next];
+ desc_addr = gpa_to_vva(dev, desc->addr);
+ desc_offset = 0;
+ desc_avail = desc->len;
+ }
+
+ COPY(desc_addr + desc_offset,
+ rte_pktmbuf_mtod_offset(m, uint64_t, mbuf_offset));
+ PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset),
+ cpy_len, 0);
+ }
+ *copied = rte_pktmbuf_pkt_len(m);
+
+ return 0;
+}
+
+/*
+ * As many data cores may want access to available buffers
+ * they need to be reserved.
+ */
+static inline uint32_t
+reserve_avail_buf(struct vhost_virtqueue *vq, uint32_t count,
+ uint16_t *start, uint16_t *end)
+{
+ uint16_t res_start_idx;
+ uint16_t res_end_idx;
+ uint16_t avail_idx;
+ uint16_t free_entries;
+ int success;
+
+ count = RTE_MIN(count, (uint32_t)MAX_PKT_BURST);
+
+again:
+ res_start_idx = vq->last_used_idx_res;
+ avail_idx = *((volatile uint16_t *)&vq->avail->idx);
+
+ free_entries = (avail_idx - res_start_idx);
+ count = RTE_MIN(count, free_entries);
+ if (count == 0)
+ return 0;
+
+ res_end_idx = res_start_idx + count;
+
+ /*
+ * update vq->last_used_idx_res atomically; try again if failed.
+ *
+ * TODO: Allow to disable cmpset if no concurrency in application.
+ */
+ success = rte_atomic16_cmpset(&vq->last_used_idx_res,
+ res_start_idx, res_end_idx);
+ if (!success)
+ goto again;
+
+ *start = res_start_idx;
+ *end = res_end_idx;
+
+ return count;
+}
+
/**
* This function adds buffers to the virtio devices RX virtqueue. Buffers can
* be received from the physical port or from another virtio device. A packet
@@ -70,21 +171,12 @@ is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t
qp_nb)
*/
static inline uint32_t __attribute__((always_inline))
virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
- struct rte_mbuf **pkts, uint32_t count)
+ struct rte_mbuf **pkts, uint32_t count)
{
struct vhost_virtqueue *vq;
- struct vring_desc *desc;
- struct rte_mbuf *buff;
- /* The virtio_hdr is initialised to 0. */
- struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, 0, 0, 0, 0, 0}, 0};
- uint64_t buff_addr = 0;
- uint64_t buff_hdr_addr = 0;
- uint32_t head[MAX_PKT_BURST];
- uint32_t head_idx, packet_success = 0;
- uint16_t avail_idx, res_cur_idx;
- uint16_t res_base_idx, res_end_idx;
- uint16_t free_entries;
- uint8_t success = 0;
+ uint16_t res_start_idx, res_end_idx;
+ uint16_t desc_indexes[MAX_PKT_BURST];
+ uint32_t i;
LOG_DEBUG(VHOST_DATA, "(%"PRIu64") virtio_dev_rx()\n", dev->device_fh);
if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->virt_qp_nb))) {
@@ -98,152 +190,43 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
if (unlikely(vq->enabled == 0))
return 0;
- count = (count > MAX_PKT_BURST) ? MAX_PKT_BURST : count;
-
- /*
- * As many data cores may want access to available buffers,
- * they need to be reserved.
- */
- do {
- res_base_idx = vq->last_used_idx_res;
- avail_idx = *((volatile uint16_t *)&vq->avail->idx);
-
- free_entries = (avail_idx - res_base_idx);
- /*check that we have enough buffers*/
- if (unlikely(count > free_entries))
- count = free_entries;
-
- if (count == 0)
- return 0;
-
- res_end_idx = res_base_idx + count;
- /* vq->last_used_idx_res is atomically updated. */
- /* TODO: Allow to disable cmpset if no concurrency in
application. */
- success = rte_atomic16_cmpset(&vq->last_used_idx_res,
- res_base_idx, res_end_idx);
- } while (unlikely(success == 0));
- res_cur_idx = res_base_idx;
- LOG_DEBUG(VHOST_DATA, "(%"PRIu64") Current Index %d| End Index %d\n",
- dev->device_fh, res_cur_idx, res_end_idx);
-
- /* Prefetch available ring to retrieve indexes. */
- rte_prefetch0(&vq->avail->ring[res_cur_idx & (vq->size - 1)]);
-
- /* Retrieve all of the head indexes first to avoid caching issues. */
- for (head_idx = 0; head_idx < count; head_idx++)
- head[head_idx] = vq->avail->ring[(res_cur_idx + head_idx) &
- (vq->size - 1)];
-
- /*Prefetch descriptor index. */
- rte_prefetch0(&vq->desc[head[packet_success]]);
-
- while (res_cur_idx != res_end_idx) {
- uint32_t offset = 0, vb_offset = 0;
- uint32_t pkt_len, len_to_cpy, data_len, total_copied = 0;
- uint8_t hdr = 0, uncompleted_pkt = 0;
+ count = reserve_avail_buf(vq, count, &res_start_idx, &res_end_idx);
+ if (count == 0)
+ return 0;
- /* Get descriptor from available ring */
- desc = &vq->desc[head[packet_success]];
+ LOG_DEBUG(VHOST_DATA,
+ "(%"PRIu64") res_start_idx %d| res_end_idx Index %d\n",
+ dev->device_fh, res_start_idx, res_end_idx);
- buff = pkts[packet_success];
+ /* 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)];
- /* Convert from gpa to vva (guest physical addr -> vhost
virtual addr) */
- buff_addr = gpa_to_vva(dev, desc->addr);
- /* Prefetch buffer address. */
- rte_prefetch0((void *)(uintptr_t)buff_addr);
+ 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;
- /* Copy virtio_hdr to packet and increment buffer address */
- buff_hdr_addr = buff_addr;
+ err = copy_mbuf_to_desc(dev, vq, pkts[i], desc_idx, &copied);
- /*
- * If the descriptors are chained the header and data are
- * placed in separate buffers.
- */
- if ((desc->flags & VRING_DESC_F_NEXT) &&
- (desc->len == vq->vhost_hlen)) {
- desc = &vq->desc[desc->next];
- /* Buffer address translation. */
- buff_addr = gpa_to_vva(dev, desc->addr);
+ vq->used->ring[used_idx].id = desc_idx;
+ if (unlikely(err)) {
+ vq->used->ring[used_idx].len = vq->vhost_hlen;
} else {
- vb_offset += vq->vhost_hlen;
- hdr = 1;
- }
-
- pkt_len = rte_pktmbuf_pkt_len(buff);
- data_len = rte_pktmbuf_data_len(buff);
- len_to_cpy = RTE_MIN(data_len,
- hdr ? desc->len - vq->vhost_hlen : desc->len);
- while (total_copied < pkt_len) {
- /* Copy mbuf data to buffer */
- rte_memcpy((void *)(uintptr_t)(buff_addr + vb_offset),
- rte_pktmbuf_mtod_offset(buff, const void *,
offset),
- len_to_cpy);
- PRINT_PACKET(dev, (uintptr_t)(buff_addr + vb_offset),
- len_to_cpy, 0);
-
- offset += len_to_cpy;
- vb_offset += len_to_cpy;
- total_copied += len_to_cpy;
-
- /* The whole packet completes */
- if (total_copied == pkt_len)
- break;
-
- /* The current segment completes */
- if (offset == data_len) {
- buff = buff->next;
- offset = 0;
- data_len = rte_pktmbuf_data_len(buff);
- }
-
- /* The current vring descriptor done */
- if (vb_offset == desc->len) {
- if (desc->flags & VRING_DESC_F_NEXT) {
- desc = &vq->desc[desc->next];
- buff_addr = gpa_to_vva(dev, desc->addr);
- vb_offset = 0;
- } else {
- /* Room in vring buffer is not enough */
- uncompleted_pkt = 1;
- break;
- }
- }
- len_to_cpy = RTE_MIN(data_len - offset, desc->len -
vb_offset);
+ vq->used->ring[used_idx].len = copied + vq->vhost_hlen;
}
- /* Update used ring with desc information */
- vq->used->ring[res_cur_idx & (vq->size - 1)].id =
- head[packet_success];
-
- /* Drop the packet if it is uncompleted */
- if (unlikely(uncompleted_pkt == 1))
- vq->used->ring[res_cur_idx & (vq->size - 1)].len =
- vq->vhost_hlen;
- else
- vq->used->ring[res_cur_idx & (vq->size - 1)].len =
- pkt_len +
vq->vhost_hlen;
-
- res_cur_idx++;
- packet_success++;
-
- if (unlikely(uncompleted_pkt == 1))
- continue;
-
- rte_memcpy((void *)(uintptr_t)buff_hdr_addr,
- (const void *)&virtio_hdr, vq->vhost_hlen);
-
- PRINT_PACKET(dev, (uintptr_t)buff_hdr_addr, vq->vhost_hlen, 1);
-
- if (res_cur_idx < res_end_idx) {
- /* Prefetch descriptor index. */
- rte_prefetch0(&vq->desc[head[packet_success]]);
- }
+ if (i + 1 < count)
+ rte_prefetch0(&vq->desc[desc_indexes[i+1]]);
}
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 != res_start_idx))
rte_pause();
*(volatile uint16_t *)&vq->used->idx += count;
--
1.9.0
