[dpdk-dev] Instability of port ids

Stephen Hemminger stephen at networkplumber.org
Sat May 18 15:33:19 CEST 2019

On Sat, 18 May 2019 06:03:22 +0000
"Wang, Haiyue" <haiyue.wang at intel.com> wrote:

> > -----Original Message-----
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Stephen Hemminger
> > Sent: Saturday, May 18, 2019 02:47
> > To: dev at dpdk.org
> > Subject: [dpdk-dev] Instability of port ids
> > 
> > Several customers have reported similar issues with how the owned/stack device model
> > works in DPDK. With failsafe/tap and VF or netvsc and VF there are DPDK ports which
> > are marked as owned and therefore not visible.
> > 
> > The problem is the application has to guess and workaround these port values in
> > the port mask that gets passed in on command line. This means a working application
> > has to modify its startup script to run on Azure. Worse the actual port values
> > change based on the number of NIC's configured.
> > 
> > Overall this is a nuisance for users. The whole DPDK port index concept is a bad
> > design. In Linux/BSD there is ifindex, but few applications care, they all use names
> > which is better. Very very few application care that eth1 is ifindex 4.
> > 
> > The whole assignment of ports is a mess as well since it is based on probe order
> > and that is based on PCI order, and not anything dependable. It gets worse with
> > command line arguments, vdev, owned devices etc.
> > 
> > All I can think of is that:
> >   * DPDK network devices need to have human readable names. current PCI is not good.
> >   * The names need to be repeatable/persistent. udev names are probably better than anything so far.
> >     Or bsd style names but they end up being device dependent.
> >   * The API to get from name to port needs to easy to use and the preferred method.
> >   * All examples and documentation should avoid using port index directly.
> >     You need port for fast rx/tx but setup should be by name.  
> idea from system like enp24s0f0 ?
> https://github.com/systemd/systemd/blob/master/docs/PREDICTABLE_INTERFACE_NAMES.md
> https://github.com/systemd/systemd/blob/master/src/udev/udev-builtin-net_id.c

The other suggestion is to use an algorithm like VPP which generates

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