vhost: inject only one interrupt for a batch of packets

In merge-able RX path, vhost injects interrupts to guest for each packet.
This should degrade performance a lot.
This patch fixes this issue by injecting one interrupt for a batch of packets.

Signed-off-by: Huawei Xie <huawei.xie@intel.com>
Acked-by: Jianfeng Tan <jianfeng.tan@intel.com>

diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index b2b2bcc..7026bfa 100644 (file)
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -496,7 +496,7 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
                                                "to get enough desc from "
                                                "vring\n",
                                                dev->device_fh);
-                                       return pkt_idx;
+                                       goto merge_rx_exit;
                                } else {
                                        update_secure_len(vq, res_cur_idx, &secure_len, &vec_idx);
                                        res_cur_idx++;
@@ -523,7 +523,10 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
 
                *(volatile uint16_t *)&vq->used->idx += entry_success;
                vq->last_used_idx = res_cur_idx;
+       }
 
+merge_rx_exit:
+       if (likely(pkt_idx)) {
                /* flush used->idx update before we read avail->flags. */
                rte_mb();
 
@@ -532,7 +535,7 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
                        eventfd_write(vq->callfd, (eventfd_t)1);
        }
 
-       return count;
+       return pkt_idx;
 }
 
 uint16_t