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

[Bruce Richardson <bruce.richardson-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

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-AlSX/UN32fvPDbFq/vQRIQ@public.gmane.org>
> > ---
> >  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?
> 
> Regards,
> /Bruce
> 

Resending with correct email addr for Neil.

/Bruce