[dpdk-users] Why kickfd from qemu is zero in qemu-dpdk vhost-user architecture?

Li Feng fengli at smartx.com
Sun Jul 15 10:49:08 CEST 2018


I think you should add some logs at vhost initialization. And what's the
error code when you call event fd?

2018年7月15日星期日,杨晔 <yangye at ict.ac.cn> 写道:

>
> Sure.
>
> Here is my code. In virtio_net.c of dpdk.
> uint16_t
> rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
>         struct rte_mempool *mbuf_pool, struct rte_mbuf **
> pkts, uint16_t count)
> {
>       ...
>         struct virtio_net *dev;
>         struct rte_mbuf *rarp_mbuf = NULL;
>         struct vhost_virtqueue *vq;
>         uint32_t desc_indexes[MAX_PKT_BURST];
>         uint32_t used_idx;
>         uint32_t i = 0;
>         uint16_t free_entries;
>         uint16_t avail_idx;
>
>         dev = get_device(vid);
>         if (!dev)
>                 return 0;
>
>         if (unlikely(!is_valid_virt_queue_idx(queue_id,
>  1, dev->nr_vring))) {
>                 RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid
> virtqueue idx %d.\n",
>                         dev->vid, __func__, queue_id);
>                 return 0;
>         }
>
>         vq = dev->virtqueue[queue_id];
>
>         uint64_t val = 0;
>         int res = eventfd_read(vq->kickfd,&val);
>         if(res != 0)
>         {
>             RTE_LOG(INFO, VHOST_DATA, "res:(%d)\n", res);
>             return 0;
>         }
>         if(val > 0)
>             RTE_LOG(INFO, VHOST_DATA, "(%llu)\n", val);
>         else
>             return 0;
>
> }
>
> I just want to use the kickfd from qemu and guest kernel, and change
> backend DPDK'mode from polling to interrupt.
>
> -----Original Messages-----
> *From:*"Li Feng" <fengli at smartx.com>
> *Sent Time:*2018-07-15 15:57:16 (Sunday)
> *To:* "杨晔" <yangye at ict.ac.cn>
> *Cc:* "users at dpdk.org" <users at dpdk.org>
> *Subject:* Re: [dpdk-users] Why kickfd from qemu is zero in qemu-dpdk
> vhost-user architecture?
>
> You could paste some code here.
>
> Is the eventfd is valid when passing to vhost?
>
> Maybe the eventfd is bad.
>
>
> Thanks,
>
> Feng Li
>
>
>
> 手机:13401157876
>
> Web:http://www.smartx.com/
>
> 地址:北京市海淀区科学院南路2号
> <https://maps.google.com/?q=%E5%8C%97%E4%BA%AC%E5%B8%82%E6%B5%B7%E6%B7%80%E5%8C%BA%E7%A7%91%E5%AD%A6%E9%99%A2%E5%8D%97%E8%B7%AF2%E5%8F%B7&entry=gmail&source=g>
> 融科资讯中心C座北楼712
>
> 2018-07-15 15:27 GMT+08:00 杨晔 <yangye at ict.ac.cn>:
>
>> Hello,
>>
>> I use the "vhost-user" mode in the qemu, and the backend is the
>> dpdk-vhost.
>>
>> But when I use the eventfd_read(vq->kickfd,&val) function. It always
>> return an error, and the val has always been 0.
>>
>> The kickfd is the eventfd that passing from qemu to vhost when the vring
>> is set up and calling the vhost_user_set_vring_kick function.
>>
>> It should be a none-zero value when there are packets in the sending
>> queue.
>>
>> The virtio-frontend should notify the backend then do the dequeue
>> operation.
>>
>> Does anyone know about this? I am looking forward to your reply.
>>
>>
>> Thank you.
>>
>>
>>
>>
>> --
>>
>>
>> Yang Ye
>>
>> Network Research Center, Institute of Computing Technology, Chinese
>> Academy of Sciences,
>>
>> NO.6 Kexueyuan South Road, Zhongguancun, Haidian District, Beijing,
>> China (100190
>> <https://maps.google.com/?q=6+Kexueyuan+South+Road,+Zhongguancun,+Haidian+District,+Beijing,+China+(100190&entry=gmail&source=g>
>> )
>
>
>
> The SmartX email address is only for business purpose. Any sent message
> that is not related to the business is not authorized or permitted by
> SmartX.
> 本邮箱为北京志凌海纳科技有限公司(SmartX)工作邮箱. 如本邮箱发出的邮件与工作无关,该邮件未得到本公司任何的明示或默示的授权.
>
>
> --
>
> Yang Ye
>
> Network Research Center, Institute of Computing Technology, Chinese
> Academy of Sciences,
>
> NO.6 Kexueyuan South Road, Zhongguancun, Haidian District, Beijing, China
> (100190
> <https://maps.google.com/?q=6+Kexueyuan+South+Road,+Zhongguancun,+Haidian+District,+Beijing,+China+(100190&entry=gmail&source=g>)
>
>


-- 

Thanks,

Feng Li



手机:13401157876

Web:http://www.smartx.com/

地址:北京市海淀区科学院南路2号融科资讯中心C座北楼712

-- 
The SmartX email address is only for business purpose. Any sent message 
that is not related to the business is not authorized or permitted by 
SmartX.
本邮箱为北京志凌海纳科技有限公司(SmartX)工作邮箱. 如本邮箱发出的邮件与工作无关,该邮件未得到本公司任何的明示或默示的授权.




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