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

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Huawei Xie
> Sent: Monday, September 21, 2015 4:16 PM
> To: dev@dpdk.org
> Subject: [dpdk-dev] [PATCH] vhost: vhost injects interrupts to guest for each
> packet
> 
> 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
> --

Acked-by: Jianfeng Tan <Jianfeng.tan@intel.com>

> 1.9.3