Re: [dpdk-dev] [PATCH v3 7/7] virtio: pick simple rx/tx func

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

On 10/22/2015 10:50 AM, Tan, Jianfeng wrote:
> On 10/22/2015 10:45 AM, Jianfeng wrote:
>
>> -----Original Message-----
>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Huawei Xie
>> Sent: Tuesday, October 20, 2015 11:30 PM
>> To: dev@dpdk.org
>> Subject: [dpdk-dev] [PATCH v3 7/7] virtio: pick simple rx/tx func
>>
>> simple rx/tx func is enabled when user specifies single segment and no
>> offload support.
>> merge-able should be disabled to use simple rxtx.
>>
>> Signed-off-by: Huawei Xie <huawei.xie@intel.com>
>> ---
>>  drivers/net/virtio/virtio_rxtx.c | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
>> index 947fc46..71f8cd4 100644
>> --- a/drivers/net/virtio/virtio_rxtx.c
>> +++ b/drivers/net/virtio/virtio_rxtx.c
>> @@ -62,6 +62,10 @@
>>  #define  VIRTIO_DUMP_PACKET(m, len) do { } while (0)  #endif
>>
>> +
>> +#define VIRTIO_SIMPLE_FLAGS ((uint32_t)ETH_TXQ_FLAGS_NOMULTSEGS
>> | \
>> +	ETH_TXQ_FLAGS_NOOFFLOADS)
>> +
>>  static int use_simple_rxtx;
>>
>>  static void
>> @@ -471,6 +475,14 @@ virtio_dev_tx_queue_setup(struct rte_eth_dev
>> *dev,
>>  		return -EINVAL;
>>  	}
>>
>> +	/* Use simple rx/tx func if single segment and no offloads */
>> +	if ((tx_conf->txq_flags & VIRTIO_SIMPLE_FLAGS) ==
>> VIRTIO_SIMPLE_FLAGS) {
>> +		PMD_INIT_LOG(INFO, "Using simple rx/tx path");
>> +		dev->tx_pkt_burst = virtio_xmit_pkts_simple;
>> +		dev->rx_pkt_burst = virtio_recv_pkts_vec;
> Whether recv side mergeable is supported is controlled by virtio_negotiate_feature().
> So "dev->rx_pkt_burst = virtio_recv_pkts_vec" should be restricted by 
> hw->guest_features & VIRTIO_NET_F_MRG_RXBUF, right?
Add this check in next version. However it will still be put here as we
want to leave us a chance to dynamically choose normal/simple rx function.
>
>> +		use_simple_rxtx = 1;
>> +	}
>> +
>>  	ret = virtio_dev_queue_setup(dev, VTNET_TQ, queue_idx,
>> vtpci_queue_idx,
>>  			nb_desc, socket_id, &vq);
>>  	if (ret < 0) {
>> --
>> 1.8.1.4
>