Re: [dpdk-dev] [PATCH v2 01/15] mbuf: add definitions of unified packet types

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Feb 10, 2015 at 12:53:52AM +0000, Zhang, Helin wrote:
> Hi Bruce
> 
> Fortunately I have Steve as the author of a sub-patch for vector PMD in this
> patch set. That means we have already taken into account the VPMD in it.
> All is workable with vPMD, and with performance result mentioned.
> Everything is done for this mbuf changes.
> 
> Regards,
> Helin
> 
I see that helin, but between applying this patch and applying the subsequent
patch for the vector PMD, the DPDK vector PMD code is broken, which would cause
problems for anyone doing a git bisect. Hence my suggestion that changes to take
account of the vpmd need to go in this patch (not just in the patch set) to
avoid having broken code following this commit.

/Bruce

> > -----Original Message-----
> > From: Richardson, Bruce
> > Sent: Monday, February 9, 2015 6:27 PM
> > To: Zhang, Helin
> > Cc: dev@dpdk.org; Cao, Waterman; Liang, Cunming; Liu, Jijiang; Ananyev,
> > Konstantin
> > Subject: Re: [PATCH v2 01/15] mbuf: add definitions of unified packet types
> > 
> > On Mon, Feb 09, 2015 at 02:40:35PM +0800, Helin Zhang wrote:
> > > As there are only 6 bit flags in ol_flags for indicating packet types,
> > > which is not enough to describe all the possible packet types hardware
> > > can recognize. For example, i40e hardware can recognize more than 150
> > > packet types. Unified packet type is composed of tunnel type, L3 type,
> > > L4 type and inner L3 type fields, and can be stored in mbuf field of
> > > 'packet_type' which is modified from 16 bits to 32 bits in mbuf structure.
> > > Accordingly, the structure of 'rte_kni_mbuf' needs to be modifed as well.
> > >
> > > Signed-off-by: Helin Zhang <helin.zhang@intel.com>
> > > Signed-off-by: Cunming Liang <cunming.liang@intel.com>
> > > Signed-off-by: Jijiang Liu <jijiang.liu@intel.com>
> > > ---
> > >  .../linuxapp/eal/include/exec-env/rte_kni_common.h |   4 +-
> > >  lib/librte_mbuf/rte_mbuf.h                         | 113
> > +++++++++++++++++++--
> > >  2 files changed, 108 insertions(+), 9 deletions(-)
> > >
> > > v2 changes:
> > > * Enlarged the packet_type field from 16 bits to 32 bits.
> > > * Redefined the packet type sub-fields.
> > > * Updated the 'struct rte_kni_mbuf' for KNI according to the mbuf changes.
> > >
> > 
> > Since these changes to the mbuf will break the operation of the vector driver,
> > that vector driver needs to be taken into account here.
> > 
> > Some suggestions/options:
> > 1. Temporarily disable the VPMD at compile time or at run time as part of this
> > patch, and put the vector changes as the next patch (re-enabling the driver too)
> > 2. Put in the minimum changes for the new mbuf layout into this patch. It will
> > make this patch a little longer, but may still be doable as it's only a couple of
> > fields changing, not the whole structure.
> > 
> > /Bruce