Re: [dpdk-dev] [PATCH v9 1/2] examples/vhost: add ioat ring space count and check

["Jiang, Cheng1" <cheng1.jiang@intel.com>]

Hi,

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Thursday, January 21, 2021 8:35 PM
> To: Jiang, Cheng1 <cheng1.jiang@intel.com>; Xia, Chenbo
> <chenbo.xia@intel.com>
> Cc: dev@dpdk.org; Hu, Jiayu <jiayu.hu@intel.com>; Yang, YvonneX
> <yvonnex.yang@intel.com>; Wang, Yinan <yinan.wang@intel.com>
> Subject: Re: [PATCH v9 1/2] examples/vhost: add ioat ring space count and
> check
> 
> 
> 
> On 1/12/21 5:38 AM, Cheng Jiang wrote:
> > Add ioat ring space count and check, if ioat ring space is not enough
> > for the next async vhost packet enqueue, then just return to prevent
> > enqueue failure. Add rte_ioat_completed_ops() fail handler.
> >
> > Signed-off-by: Cheng Jiang <Cheng1.jiang@intel.com>
> > Reviewed-by: Jiayu Hu <jiayu.hu@intel.com>
> > Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> > ---
> >  examples/vhost/ioat.c | 24 +++++++++++++-----------
> >  1 file changed, 13 insertions(+), 11 deletions(-)
> >
> > diff --git a/examples/vhost/ioat.c b/examples/vhost/ioat.c index
> > 71d8a1f1f..dbad28d43 100644
> > --- a/examples/vhost/ioat.c
> > +++ b/examples/vhost/ioat.c
> > @@ -17,6 +17,7 @@ struct packet_tracker {
> >  	unsigned short next_read;
> >  	unsigned short next_write;
> >  	unsigned short last_remain;
> > +	unsigned short ioat_space;
> >  };
> >
> >  struct packet_tracker cb_tracker[MAX_VHOST_DEVICE]; @@ -113,7 +114,7
> > @@ open_ioat(const char *value)
> >  			goto out;
> >  		}
> >  		rte_rawdev_start(dev_id);
> > -
> > +		cb_tracker[dev_id].ioat_space = IOAT_RING_SIZE;
> >  		dma_info->nr++;
> >  		i++;
> >  	}
> > @@ -140,13 +141,9 @@ ioat_transfer_data_cb(int vid, uint16_t queue_id,
> >  			src = descs[i_desc].src;
> >  			dst = descs[i_desc].dst;
> >  			i_seg = 0;
> > +			if (cb_tracker[dev_id].ioat_space < src->nr_segs)
> > +				break;
> >  			while (i_seg < src->nr_segs) {
> > -				/*
> > -				 * TODO: Assuming that the ring space of the
> > -				 * IOAT device is large enough, so there is no
> > -				 * error here, and the actual error handling
> > -				 * will be added later.
> > -				 */
> >  				rte_ioat_enqueue_copy(dev_id,
> >  					(uintptr_t)(src->iov[i_seg].iov_base)
> >  						+ src->offset,
> > @@ -158,7 +155,8 @@ ioat_transfer_data_cb(int vid, uint16_t queue_id,
> >  				i_seg++;
> >  			}
> >  			write &= mask;
> > -			cb_tracker[dev_id].size_track[write] = i_seg;
> > +			cb_tracker[dev_id].size_track[write] = src->nr_segs;
> > +			cb_tracker[dev_id].ioat_space -= src->nr_segs;
> >  			write++;
> >  		}
> >  	} else {
> > @@ -178,17 +176,21 @@ ioat_check_completed_copies_cb(int vid,
> uint16_t
> > queue_id,  {
> >  	if (!opaque_data) {
> >  		uintptr_t dump[255];
> > -		unsigned short n_seg;
> > +		int n_seg;
> >  		unsigned short read, write;
> >  		unsigned short nb_packet = 0;
> >  		unsigned short mask = MAX_ENQUEUED_SIZE - 1;
> >  		unsigned short i;
> > +
> >  		int dev_id = dma_bind[vid].dmas[queue_id * 2
> >  				+ VIRTIO_RXQ].dev_id;
> >  		n_seg = rte_ioat_completed_ops(dev_id, 255, dump, dump);
> > -		n_seg += cb_tracker[dev_id].last_remain;
> > -		if (!n_seg)
> > +		if (n_seg <= 0)
> >  			return 0;
> 
> In a separate patch, it might make sense to propagate the error if
> rte_ioat_completed_ops return -1.

Sure, I'll send a patch to fix it when this patch set is merged.

Thanks,
Cheng

> 
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> 
> Maxime
> > +
> > +		cb_tracker[dev_id].ioat_space += n_seg;
> > +		n_seg += cb_tracker[dev_id].last_remain;
> > +
> >  		read = cb_tracker[dev_id].next_read;
> >  		write = cb_tracker[dev_id].next_write;
> >  		for (i = 0; i < max_packets; i++) {
> > --
> > 2.29.2
> >