[dpdk-dev] [PATCH v2 3/3] net/virtio: improve batching in mergeable path
Maxime Coquelin
maxime.coquelin at redhat.com
Wed Dec 19 13:08:16 CET 2018
On 12/19/18 10:47 AM, Jens Freimann wrote:
> On Tue, Dec 11, 2018 at 02:48:04PM +0100, Maxime Coquelin wrote:
>> This patch improves both descriptors dequeue and refill,
>> by using the same bathing strategy as done in in-order path.
>
> s/bathing/batching/
>
>>
>> Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
>> ---
>> drivers/net/virtio/virtio_rxtx.c | 237 ++++++++++++++++---------------
>> 1 file changed, 126 insertions(+), 111 deletions(-)
>>
>> diff --git a/drivers/net/virtio/virtio_rxtx.c
>> b/drivers/net/virtio/virtio_rxtx.c
>> index ebe5c74b5..59bcac2f7 100644
>> --- a/drivers/net/virtio/virtio_rxtx.c
>> +++ b/drivers/net/virtio/virtio_rxtx.c
>> @@ -267,41 +267,42 @@ virtqueue_enqueue_refill_inorder(struct
>> virtqueue *vq,
>> }
>>
>> static inline int
>> -virtqueue_enqueue_recv_refill(struct virtqueue *vq, struct rte_mbuf
>> *cookie)
>> +virtqueue_enqueue_recv_refill(struct virtqueue *vq, struct rte_mbuf
>> **cookie,
>> + uint16_t num)
>> {
>> struct vq_desc_extra *dxp;
>> struct virtio_hw *hw = vq->hw;
>> - struct vring_desc *start_dp;
>> - uint16_t needed = 1;
>> - uint16_t head_idx, idx;
>> + struct vring_desc *start_dp = vq->vq_ring.desc;
>> + uint16_t idx, i;
>>
>> if (unlikely(vq->vq_free_cnt == 0))
>> return -ENOSPC;
>> - if (unlikely(vq->vq_free_cnt < needed))
>> + if (unlikely(vq->vq_free_cnt < num))
>> return -EMSGSIZE;
>>
>> - head_idx = vq->vq_desc_head_idx;
>> - if (unlikely(head_idx >= vq->vq_nentries))
>> + if (unlikely(vq->vq_desc_head_idx >= vq->vq_nentries))
>> return -EFAULT;
>>
>> - idx = head_idx;
>> - dxp = &vq->vq_descx[idx];
>> - dxp->cookie = (void *)cookie;
>> - dxp->ndescs = needed;
>> + for (i = 0; i < num; i++) {
>> + idx = vq->vq_desc_head_idx;
>> + dxp = &vq->vq_descx[idx];
>> + dxp->cookie = (void *)cookie[i];
>
> I think code is safe as it is, but should we check if cookie actually
> points to something?
I don't think it is needed, we check in virtqueue_dequeue_burst_rx that
cookie isn't NULL before using it.
Thanks,
Maxime
> I tested this patch and saw the same performance improvement, so
>
> Tested-by: Jens Freimann <jfreimann at redhat.com>
> Reviewed-by: Jens Freimann <jfreimann at redhat.com>
>
> regards,
> Jens
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