Re: [dpdk-dev] [PATCH] virtio: split virtio rx/tx queue

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

On 5/5/2016 7:59 AM, Yuanhan Liu wrote:
> On Wed, May 04, 2016 at 08:50:27AM +0800, Huawei Xie wrote:
>> -int virtio_dev_queue_setup(struct rte_eth_dev *dev,
>> -			int queue_type,
>> -			uint16_t queue_idx,
>> +static int
>> +virtio_dev_cq_queue_setup(struct rte_eth_dev *dev,
> While it's good to split Rx/Tx specific stuff, but why are you trying to
> remove a common queue_setup function that does common setups, such as vring
> memory allocation.
>
> This results to much duplicated code: following diff summary also shows
> it clearly:

The motivation to do this is we need separate RX/TX queue setup.
The switch/case in the common queue setup looks bad.

I am aware of the common operations, and i had planned to extract them,
maybe i could do this in this patchset.


>
>     7 files changed, 655 insertions(+), 422 deletions(-)
>
> which makes it harder for maintaining.
>
>> -}
>> +	rxvq = (struct virtnet_rx *)RTE_PTR_ADD(vq,
>> +			sizeof(*vq) + vq_size * sizeof(struct vq_desc_extra));
>> +	rxvq->vq = vq;
>> +	vq->sw_ring = sw_ring;
> sw_ring is needed for rx queue only, why not moving it to rx queue struct?

Actually this is not about sw_ring.
I had planned to use sw_ring for both RX/TX and remove the vq_desc_extra.
Two issues
1. RX uses both sw_ring and vq_desc_extra
2. ndescs in vq_desc_extra isn't really needed, we could simply
calculate this when we walk through the desc chain, and in most cases,
it is 1 or 2.

As it is not related to this rework, will do this in a separate patch.

>
>>  static void
>> -virtio_update_packet_stats(struct virtqueue *vq, struct rte_mbuf *mbuf)
>> +virtio_update_rxq_stats(struct virtnet_rx *rxvq, struct rte_mbuf *mbuf)
>>  {
>>  	uint32_t s = mbuf->pkt_len;
>>  	struct ether_addr *ea;
>>  
>>  	if (s == 64) {
>> -		vq->size_bins[1]++;
>> +		rxvq->stats.size_bins[1]++;
>>  	} else if (s > 64 && s < 1024) {
>>  		uint32_t bin;
>>  
>>  		/* count zeros, and offset into correct bin */
>>  		bin = (sizeof(s) * 8) - __builtin_clz(s) - 5;
>> -		vq->size_bins[bin]++;
>> +		rxvq->stats.size_bins[bin]++;
>>  	} else {
>>  		if (s < 64)
>> -			vq->size_bins[0]++;
>> +			rxvq->stats.size_bins[0]++;
>>  		else if (s < 1519)
>> -			vq->size_bins[6]++;
>> +			rxvq->stats.size_bins[6]++;
>>  		else if (s >= 1519)
>> -			vq->size_bins[7]++;
>> +			rxvq->stats.size_bins[7]++;
>>  	}
>>  
>>  	ea = rte_pktmbuf_mtod(mbuf, struct ether_addr *);
>>  	if (is_multicast_ether_addr(ea)) {
>>  		if (is_broadcast_ether_addr(ea))
>> -			vq->broadcast++;
>> +			rxvq->stats.broadcast++;
>>  		else
>> -			vq->multicast++;
>> +			rxvq->stats.multicast++;
>> +	}
>> +}
>> +
>> +static void
>> +virtio_update_txq_stats(struct virtnet_tx *txvq, struct rte_mbuf *mbuf)
> Why not taking "struct virtnet_stats *stats" as the arg, so that we
> don't have to implment two exactly same functions.

ok to me.

>
>> diff --git a/drivers/net/virtio/virtio_rxtx.h b/drivers/net/virtio/virtio_rxtx.h
>> index a76c3e5..ced55a3 100644
>> --- a/drivers/net/virtio/virtio_rxtx.h
>> +++ b/drivers/net/virtio/virtio_rxtx.h
>> @@ -34,7 +34,59 @@
>>  #define RTE_PMD_VIRTIO_RX_MAX_BURST 64
>>  
>>  #ifdef RTE_MACHINE_CPUFLAG_SSSE3
>> -int virtio_rxq_vec_setup(struct virtqueue *rxq);
>> +
>> +struct virtnet_stats {
> Another remind again: you should put following codes before the
> "#ifdef".
>
> 	--yliu
>