Re: [dpdk-dev] [PATCH v6 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: Tuesday, January 5, 2021 9:20 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>; Wang, Yinan
> <yinan.wang@intel.com>
> Subject: RE: [PATCH v6 1/2] examples/vhost: add ioat ring space count and
> check
> 
> Hi Cheng,
> 
> > -----Original Message-----
> > From: Jiang, Cheng1 <cheng1.jiang@intel.com>
> > Sent: Monday, January 4, 2021 12:58 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>; Wang, Yinan <yinan.wang@intel.com>; Jiang,
> > Cheng1 <cheng1.jiang@intel.com>
> > Subject: [PATCH v6 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. Add rte_ioat_completed_ops() fail handler.
> >
> > Signed-off-by: Cheng Jiang <Cheng1.jiang@intel.com>
> > ---
> >  examples/vhost/ioat.c | 22 ++++++++++++----------
> >  1 file changed, 12 insertions(+), 10 deletions(-)
> >
> > diff --git a/examples/vhost/ioat.c b/examples/vhost/ioat.c index
> > 71d8a1f1f5..679d1e2f58 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)  return 0;
> > +
> > +cb_tracker[dev_id].ioat_space += n_seg; n_seg +=
> > +cb_tracker[dev_id].last_remain;
> 
> When error happens in rte_ioat_completed_ops(), where n_seg is -1, the
> value of "!n_seg" is false (0) and it can still pass the check of "if".
> 

You are right, I think I just missed that
I will fix it in the next version, thanks a lot.

Cheng

> Thanks,
> Jiayu
> > +
> >  read = cb_tracker[dev_id].next_read;
> >  write = cb_tracker[dev_id].next_write;  for (i = 0; i < max_packets;
> > i++) {
> > --
> > 2.29.2
>