[dpdk-dev] [PATCH v3] examples/vhost: remove async inflight packet counter

[Maxime Coquelin]

On 2/3/21 2:42 PM, Jiang, Cheng1 wrote:
> 
> 
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coquelin at redhat.com>
>> Sent: Wednesday, February 3, 2021 8:55 PM
>> To: Jiang, Cheng1 <cheng1.jiang at intel.com>; Xia, Chenbo
>> <chenbo.xia at intel.com>
>> Cc: dev at dpdk.org; Hu, Jiayu <jiayu.hu at intel.com>; Yang, YvonneX
>> <yvonnex.yang at intel.com>; Wang, Yinan <yinan.wang at intel.com>
>> Subject: Re: [PATCH v3] examples/vhost: remove async inflight packet
>> counter
>>
>>
>>
>> On 2/3/21 1:11 PM, Jiang, Cheng1 wrote:
>>> Hi,
>>>
>>>> -----Original Message-----
>>>> From: Maxime Coquelin <maxime.coquelin at redhat.com>
>>>> Sent: Wednesday, February 3, 2021 5:52 PM
>>>> To: Jiang, Cheng1 <cheng1.jiang at intel.com>; Xia, Chenbo
>>>> <chenbo.xia at intel.com>
>>>> Cc: dev at dpdk.org; Hu, Jiayu <jiayu.hu at intel.com>; Yang, YvonneX
>>>> <yvonnex.yang at intel.com>; Wang, Yinan <yinan.wang at intel.com>
>>>> Subject: Re: [PATCH v3] examples/vhost: remove async inflight packet
>>>> counter
>>>>
>>>>
>>>>
>>>> On 2/2/21 7:17 AM, Cheng Jiang wrote:
>>>>> Remove async inflight packet counter since there is no need to keep
>>>>> tracking it. Increase MAX_ENQUEUED_SIZE to prevent packet segment
>>>>> number tracking ring from being exhausted.
>>>>
>>>> Is that an optimization or a fix?
>>>>
>>>> If the former, let's move it to v21.05.
>>>>
>>>
>>> I think it's a fix since there is no need to keep the inflight packet counter,
>> sorry I forget adding the fixes, I can submit a v4 to fix it.
>> OK
>>>>>
>>>>> Fixes: a68ba8e0a6b6 ("examples/vhost: refactor vhost data path")
> 
> Oh, I got fixes here, sorry for the miss.
> 
>>>>>
>>>>> Signed-off-by: Cheng Jiang <Cheng1.jiang at intel.com>
>>>>> ---
>>>>> v3: fixed fixes commit id in git log
>>>>>
>>>>> v2: fixed a typo
>>>>>
>>>>>  examples/vhost/ioat.h |  2 +-
>>>>>  examples/vhost/main.c | 10 +---------  examples/vhost/main.h |  1 -
>>>>>  3 files changed, 2 insertions(+), 11 deletions(-)
>>>>>
>>>>> diff --git a/examples/vhost/ioat.h b/examples/vhost/ioat.h index
>>>>> 0a1dbb811..1aa28ed6a 100644
>>>>> --- a/examples/vhost/ioat.h
>>>>> +++ b/examples/vhost/ioat.h
>>>>> @@ -11,7 +11,7 @@
>>>>>
>>>>>  #define MAX_VHOST_DEVICE 1024
>>>>>  #define IOAT_RING_SIZE 4096
>>>>> -#define MAX_ENQUEUED_SIZE 512
>>>>> +#define It might be further simplified then 4096
>>>>
>>>> Basically, this the size of the ring size, correct?
>>>> It might be further simplified then.
>>>>
>>>
>>> Yes, it's a the size of packet tracking ring, and it should be no less then
>> IOAT_RING_SIZE for some corner cases.
>>> I'm not sure I understand what you mean by saying It might be further
>> simplified then.
>>
>> I meant maybe in this case just use IOAT_RING_SIZE?
> 
> I have thought about it before I use MAX_ENQUEUED_SIZE.
> But actually MAX_ENQUEUED_SIZE is used to for packet tracking ring, and IOAT_RING_SIZE is for ioat ring.
> Using IOAT_RING_SIZE for packet tracking ring, I think maybe it's not so logical and a little bit confusing. What do you think?

OK, let's keep it as is then.

Thanks,
Maxime

> Thanks,
> Cheng
> 
>>
>>> Thanks,
>>> Cheng
>>>
>>>>>
>>>>>  struct dma_info {
>>>>>  	struct rte_pci_addr addr;
>>>>> diff --git a/examples/vhost/main.c b/examples/vhost/main.c index
>>>>> e74fc8750..ca73e7086 100644
>>>>> --- a/examples/vhost/main.c
>>>>> +++ b/examples/vhost/main.c
>>>>> @@ -831,11 +831,8 @@ complete_async_pkts(struct vhost_dev *vdev)
>>>>>
>>>>>  	complete_count = rte_vhost_poll_enqueue_completed(vdev->vid,
>>>>>  					VIRTIO_RXQ, p_cpl,
>>>> MAX_PKT_BURST);
>>>>> -	if (complete_count) {
>>>>> -		__atomic_sub_fetch(&vdev->nr_async_pkts,
>>>> complete_count,
>>>>> -			__ATOMIC_SEQ_CST);
>>>>> +	if (complete_count)
>>>>>  		free_pkts(p_cpl, complete_count);
>>>>> -	}
>>>>>  }
>>>>>
>>>>>  static __rte_always_inline void
>>>>> @@ -878,8 +875,6 @@ drain_vhost(struct vhost_dev *vdev)
>>>>>  		complete_async_pkts(vdev);
>>>>>  		ret = rte_vhost_submit_enqueue_burst(vdev->vid,
>>>> VIRTIO_RXQ,
>>>>>  					m, nr_xmit, m_cpu_cpl,
>>>> &cpu_cpl_nr);
>>>>> -		__atomic_add_fetch(&vdev->nr_async_pkts, ret -
>>>> cpu_cpl_nr,
>>>>> -				__ATOMIC_SEQ_CST);
>>>>>
>>>>>  		if (cpu_cpl_nr)
>>>>>  			free_pkts(m_cpu_cpl, cpu_cpl_nr); @@ -1210,9
>> +1205,6 @@
>>>>> drain_eth_rx(struct vhost_dev *vdev)
>>>>>  		enqueue_count = rte_vhost_submit_enqueue_burst(vdev-
>>>>> vid,
>>>>>  					VIRTIO_RXQ, pkts, rx_count,
>>>>>  					m_cpu_cpl, &cpu_cpl_nr);
>>>>> -		__atomic_add_fetch(&vdev->nr_async_pkts,
>>>>> -					enqueue_count - cpu_cpl_nr,
>>>>> -					__ATOMIC_SEQ_CST);
>>>>>  		if (cpu_cpl_nr)
>>>>>  			free_pkts(m_cpu_cpl, cpu_cpl_nr);
>>>>>
>>>>> diff --git a/examples/vhost/main.h b/examples/vhost/main.h index
>>>>> 2d6c05fd7..0ccdce4b4 100644
>>>>> --- a/examples/vhost/main.h
>>>>> +++ b/examples/vhost/main.h
>>>>> @@ -51,7 +51,6 @@ struct vhost_dev {
>>>>>  	uint64_t features;
>>>>>  	size_t hdr_len;
>>>>>  	uint16_t nr_vrings;
>>>>> -	uint64_t nr_async_pkts;
>>>>>  	struct rte_vhost_memory *mem;
>>>>>  	struct device_statistics stats;
>>>>>  	TAILQ_ENTRY(vhost_dev) global_vdev_entry;
>>>>> --
>>>>> 2.29.2
>>>>>
>>>
>