Hi Junjie, > -----Original Message----- > From: Chen, Junjie J > Sent: Saturday, February 24, 2018 10:44 PM > To: y...@fridaylinux.org; maxime.coque...@redhat.com; Tan, Jianfeng > Cc: dev@dpdk.org; Chen, Junjie J > Subject: [PATCH] doc: add driver limitation for vhost dequeue zero copy > > In vhost-switch example, when binding nic to vfio-pci, dequeue zero > copy cannot work in VM2NIC mode due to no iommu dma mapping is setup > for guest memory currently.
IMO, it's a limitation that can be fixed. Do you want to try fixing it? > > Signed-off-by: Junjie Chen <junjie.j.c...@intel.com> > --- > doc/guides/sample_app_ug/vhost.rst | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/doc/guides/sample_app_ug/vhost.rst > b/doc/guides/sample_app_ug/vhost.rst > index a4bdc6a..1591a31 100644 > --- a/doc/guides/sample_app_ug/vhost.rst > +++ b/doc/guides/sample_app_ug/vhost.rst Besides, we might also need to put such limitation at http://dpdk.org/doc/guides/prog_guide/vhost_lib.html Thanks, Jianfeng > @@ -147,7 +147,10 @@ retries on an RX burst, it takes effect only when rx > retry is enabled. The > default value is 15. > > **--dequeue-zero-copy** > -Dequeue zero copy will be enabled when this option is given. > +Dequeue zero copy will be enabled when this option is given, it is worth to > +note that if NIC is binded to vfio-pci driver, dequeue zero copy cannot work > +at VM2NIC mode (vm2vm=0) due to currently we don't setup iommu dma > mapping for > +guest memory. > > **--vlan-strip 0|1** > VLAN strip option is removed, because different NICs have different > behaviors > -- > 2.0.1
