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

Jiang, Cheng1 cheng1.jiang at intel.com
Wed Feb 3 14:42:13 CET 2021



> -----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?

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
> >>>
> >



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