Re: [dpdk-dev] [RFC PATCH] lib/librte_ethdev: Expand port identifier

["Wodkowski, PawelX" <pawelx.wodkowski@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> Sent: Wednesday, February 18, 2015 1:32 PM
> To: Tetsuya Mukawa
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [RFC PATCH] lib/librte_ethdev: Expand port identifier
> 
> On Wed, Feb 18, 2015 at 12:30:07PM +0000, Bruce Richardson wrote:
> > On Wed, Feb 18, 2015 at 08:02:49PM +0900, Tetsuya Mukawa wrote:
> > > Currently uint8_t is used for port identifier. This patch changes it,
> > > and use uint16_t as port identifier.
> > > This patch only changes ethdev library. ABI of the library will be
> > > kept even after applying it.
> > >
> > > Also, this patch involves following fixes.
> > > - Use "port_id" as variable name instead of "port".
> > >
> > >
> > > Signed-off-by: Tetsuya Mukawa <mukawa@igel.co.jp>
> > > ---
> > >  lib/librte_ether/rte_ethdev.c          |  212 +-
> > >  lib/librte_ether/rte_ethdev_internal.h | 3672
> ++++++++++++++++++++++++++++++++
> > >  2 files changed, 3778 insertions(+), 106 deletions(-)
> > >  create mode 100644 lib/librte_ether/rte_ethdev_internal.h
> > >
> > I'm not sure I follow why we need a new header file for this.
> > Also, thinking about this change, a more fundamental problem is going to be
> > the mbuf structure, which stores a port id inside it in an 8-bit value.
> > Upgrading that to a 16-bit value requires some thought, and verification to
> > ensure any adjustment of fields does not lead to serious performance issues.
> >
> > Therefore, I suggest we leave the port id values as 8-bits until such time
> > as we need greater than 255 port values in a real-world use case.
> > Out of interest - anyone have a DPDK app where they use >16 port id values? If
> > so, how high does the port id value get?

Not real application but simple example of setup:
4 Niantic x 2 ports x 64 VF = 512 port id

I don't know what would be the real need/advantage of such setup (bonding?) but 
you see, in theory it is already insufficient.

> >
> > Regards,
> > /Bruce
> >
> 
> Resending with correct email addr for Neil.
> 
> /Bruce