Re: [dpdk-dev] [PATCH v4 1/2] examples/vhost: add ioat ring space count and check

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

Hi Jiayu,

> -----Original Message-----
> From: Hu, Jiayu <jiayu.hu@intel.com>
> Sent: Monday, December 28, 2020 10:51 AM
> To: Jiang, Cheng1 <cheng1.jiang@intel.com>; maxime.coquelin@redhat.com;
> Xia, Chenbo <chenbo.xia@intel.com>
> Cc: dev@dpdk.org; Yang, YvonneX <yvonnex.yang@intel.com>
> Subject: RE: [PATCH v4 1/2] examples/vhost: add ioat ring space count and
> check
> 
> Hi Cheng,
> 
> > -----Original Message-----
> > From: Jiang, Cheng1 <cheng1.jiang@intel.com>
> > Sent: Friday, December 25, 2020 4:07 PM
> > To: maxime.coquelin@redhat.com; Xia, Chenbo <chenbo.xia@intel.com>
> > Cc: dev@dpdk.org; Hu, Jiayu <jiayu.hu@intel.com>; Yang, YvonneX
> > <yvonnex.yang@intel.com>; Jiang, Cheng1 <cheng1.jiang@intel.com>
> > Subject: [PATCH v4 1/2] examples/vhost: add ioat ring space count and
> > check
> >
> > 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.
> >
> > Signed-off-by: Cheng Jiang <Cheng1.jiang@intel.com>
> > ---
> >  examples/vhost/ioat.c | 15 +++++++--------
> >  1 file changed, 7 insertions(+), 8 deletions(-)
> >
> > diff --git a/examples/vhost/ioat.c b/examples/vhost/ioat.c index
> > 71d8a1f1f..b0b04aa45 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 {
> > @@ -186,6 +184,7 @@ ioat_check_completed_copies_cb(int vid, uint16_t
> > queue_id,  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);
> > +cb_tracker[dev_id].ioat_space += n_seg;
> 
> rte_ioat_completed_ops() may fail. In this case, its return value is -1, which
> will cause n_seg to 65534.

I will change it in the next version.

Thanks.
Cheng

> 
> Thanks,
> Jiayu
> 
> >  n_seg += cb_tracker[dev_id].last_remain;  if (!n_seg)  return 0;
> > --
> > 2.29.2
>