[dpdk-dev] [PATCH] examples/vhost: fix ioat ring space in callbacks

[Jiang, Cheng1]

Hi,

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin at redhat.com>
> Sent: Tuesday, April 13, 2021 4:51 PM
> To: Hu, Jiayu <jiayu.hu at intel.com>; Jiang, Cheng1 <cheng1.jiang at intel.com>;
> Xia, Chenbo <chenbo.xia at intel.com>; Thomas Monjalon
> <thomas at monjalon.net>
> Cc: dev at dpdk.org; Yang, YvonneX <yvonnex.yang at intel.com>; Wang, Yinan
> <yinan.wang at intel.com>; stable at dpdk.org
> Subject: Re: [PATCH] examples/vhost: fix ioat ring space in callbacks
> 
> 
> 
> On 4/7/21 9:54 AM, Hu, Jiayu wrote:
> > Hi Maxime,
> >
> >> -----Original Message-----
> >> From: Maxime Coquelin <maxime.coquelin at redhat.com>
> >> Sent: Wednesday, April 7, 2021 3:48 PM
> >> To: Jiang, Cheng1 <cheng1.jiang at intel.com>; Xia, Chenbo
> >> <chenbo.xia at intel.com>; Thomas Monjalon <thomas at monjalon.net>
> >> 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>;
> >> stable at dpdk.org
> >> Subject: Re: [PATCH] examples/vhost: fix ioat ring space in callbacks
> >>
> >>
> >>
> >> On 3/17/21 6:40 AM, Cheng Jiang wrote:
> >>> We use ioat ring space for determining if ioat callbacks can enqueue
> >>> a packet to ioat device. But there is one slot can't be used in ioat
> >>> ring due to the ioat driver design, so we need to reduce one slot in
> >>> ioat ring to prevent ring size mismatch in ioat callbacks.
> >>>
> >>> Fixes: 2aa47e94bfb2 ("examples/vhost: add ioat ring space count and
> >> check")
> >>> Cc: stable at dpdk.org
> >>>
> >>> Signed-off-by: Cheng Jiang <Cheng1.jiang at intel.com>
> >>> ---
> >>>  examples/vhost/ioat.c | 2 +-
> >>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/examples/vhost/ioat.c b/examples/vhost/ioat.c index
> >>> 60b73be93..9cb5e0d50 100644
> >>> --- a/examples/vhost/ioat.c
> >>> +++ b/examples/vhost/ioat.c
> >>> @@ -113,7 +113,7 @@ open_ioat(const char *value)
> >>>  			goto out;
> >>>  		}
> >>>  		rte_rawdev_start(dev_id);
> >>> -		cb_tracker[dev_id].ioat_space = IOAT_RING_SIZE;
> >>> +		cb_tracker[dev_id].ioat_space = IOAT_RING_SIZE - 1;
> >>
> >> That really comforts me in thinking we need a generic abstraction for
> >> DMA devices. How is the application developer supposed to know that
> >> the DMA driver has such weird limitations?
> >>
> >> Can the driver be fixed to have a proper behavior?
> >
> > Here is the patch of providing capacity check API for DMA:
> > http://patches.dpdk.org/project/dpdk/patch/20210318182042.43658-6-
> bruc
> > e.richardson at intel.com/
> 
> OK, thanks for the pointer.
> 
> While this new API is being reviewed, and for LTS, let's pick your patch. As
> soon as Bruce patch is merged, please send a new patch on top to make use
> of this API.

Sure, thanks a lot.
Cheng

> 
> Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
> 
> Thanks,
> Maxime
> 
> > Thanks,
> > Jiayu
> >>
> >>>  		dma_info->nr++;
> >>>  		i++;
> >>>  	}
> >>>
> >