On Mon, May 30, 2022 at 06:33:14AM +0100, Xia, Chenbo wrote: > Hi Bruce, > > > -----Original Message----- > > From: Richardson, Bruce <bruce.richard...@intel.com> > > Sent: Saturday, May 28, 2022 12:37 AM > > To: dev@dpdk.org > > Cc: Maxime Coquelin <maxime.coque...@redhat.com>; Xia, Chenbo > > <chenbo....@intel.com>; Richardson, Bruce <bruce.richard...@intel.com> > > Subject: [PATCH v2 1/2] doc/howto: rework section on virtio-user as > > exception path > > > > This patch extensively reworks the howto guide on using virtio-user for > > exception packets. Changes include: > > > > * rename "exceptional path" to "exception path" > > * remove references to uio and just reference vfio-pci > > * simplify testpmd command-lines, giving a basic usage example first > > before adding on detail about checksum or TSO parameters > > * give a complete working example showing traffic flowing through the > > whole system from a testpmd loopback using the created TAP netdev > > * replace use of "ifconfig" with Linux standard "ip" command > > * other general rewording. > > > > Signed-off-by: Bruce Richardson <bruce.richard...@intel.com> > > > > --- > > v2: fix checkpatch warnings > > --- > > .../howto/virtio_user_as_exceptional_path.rst | 159 +++++++++++------- > > I agree with the renaming. And should we rename this file, and if possible, > the > attached img too. >
I wasn't sure of the value of doing such a rename - afraid it might clobber up the git history. I'll add it as a separate patch in a v3. > > 1 file changed, 100 insertions(+), 59 deletions(-) > > > > diff --git a/doc/guides/howto/virtio_user_as_exceptional_path.rst > > b/doc/guides/howto/virtio_user_as_exceptional_path.rst > > index ec021af399..100376c32d 100644 > > --- a/doc/guides/howto/virtio_user_as_exceptional_path.rst > > +++ b/doc/guides/howto/virtio_user_as_exceptional_path.rst > > @@ -3,116 +3,157 @@ > > > > .. _virtio_user_as_exceptional_path: > > > > -Virtio_user as Exceptional Path > > -=============================== > > +Virtio_user as Exception Path > > +============================= > > > > -The virtual device, virtio-user, was originally introduced with vhost- > > user > > -backend, as a high performance solution for IPC (Inter-Process > > Communication) > > +.. note:: > > + > > + This solution is only applicable to Linux systems. > > + > > +The virtual device, virtio-user, was originally introduced with the > > vhost-user > > +backend as a high performance solution for IPC (Inter-Process > > Communication) > > and user space container networking. > > > > -Virtio_user with vhost-kernel backend is a solution for exceptional path, > > -such as KNI which exchanges packets with kernel networking stack. This > > -solution is very promising in: > > +Beyond this originally intended use, virtio-user can be used in > > conjunction with the vhost-kernel > > +backend as a solution for dealing with exception path packets which need > > to be injected into the > > +Linux kernel for processing there. > > +In this regard, virtio-user and vhost in kernel space are an alternative > > to DPDK KNI for > > +transferring packets between a DPDK packet processing application and the > > kernel stack. > > + > > +This solution has a number of advantages over alternatives such as KNI: > > > > * Maintenance > > > > All kernel modules needed by this solution, vhost and vhost-net > > (kernel), > > - are upstreamed and extensively used kernel module. > > + are upstreamed and extensively used. > > > > * Features > > > > - vhost-net is born to be a networking solution, which has lots of > > networking > > - related features, like multi queue, tso, multi-seg mbuf, etc. > > + vhost-net is designed to be a networking solution, and, as such, has > > lots of networking > > + related features, such as multi queue support, TSO, multi-segment > > buffer support, etc. > > > > * Performance > > > > - similar to KNI, this solution would use one or more kthreads to > > - send/receive packets to/from user space DPDK applications, which has > > little > > - impact on user space polling thread (except that it might enter into > > kernel > > - space to wake up those kthreads if necessary). > > + similar to KNI, this solution would uses one or more kthreads to > > + send/receive packets to/from user space DPDK applications, which > > minimises the impact > > + on the polling DPDK threads. > > > > -The overview of an application using virtio-user as exceptional path is > > shown > > +The overview of an application using virtio-user as exception path is > > shown > > in :numref:`figure_virtio_user_as_exceptional_path`. > > > > .. _figure_virtio_user_as_exceptional_path: > > > > .. figure:: img/virtio_user_as_exceptional_path.* > > > > - Overview of a DPDK app using virtio-user as exceptional path > > + Overview of a DPDK app using virtio-user as exception path > > + > > > > +Example Usage With Testpmd > > +--------------------------- > > > > -Sample Usage > > ------------- > > +.. note:: > > + > > + These instruction assume that the vhost/vhost-net kernel modules are > > available and have already > > + been loaded into the running kernel. > > + It also assumes that the DPDK virtio driver has not been disabled in > > the DPDK build. > > > > -As a prerequisite, the vhost/vhost-net kernel CONFIG should be chosen > > before > > -compiling the kernel and those kernel modules should be inserted. > > +To run a simple test of virtio-user as exception path using testpmd: > > > > -#. Compile DPDK and bind a physical NIC to igb_uio/uio_pci_generic/vfio- > > pci. > > +#. Compile DPDK and bind a NIC to vfio-pci as documented > > in :ref:`linux_gsg_linux_drivers`. > > > > - This physical NIC is for communicating with outside. > > + This physical NIC is for communicating with the outside world, > > + and serves as a packet source in this example. > > > > -#. Run testpmd. > > +#. Run testpmd to forward packets from NIC to kernel, > > + passing in a suitable list of logical cores to run on (``- > > l``.parameter), > > This '.' should be a space? > Thanks, good catch.
