[dpdk-dev] [PATCH] vhost: vhost injects interrupts to guest for each packet

[Huawei Xie <huawei.xie@intel.com>]

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>
---
 lib/librte_vhost/vhost_rxtx.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index 0d07338..9d3165a 100644
--- 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((int)vq->callfd, 1);
 	}
 
-	return count;
+	return pkt_idx;
 }
 
 uint16_t
-- 
1.9.3