Re: [dpdk-dev] [PATCH v2 1/3] ethdev: add new RSS types for IPv6 prefix

[Thomas Monjalon <thomas@monjalon.net>]

08/07/2020 14:37, Zhang, Qi Z:
> From: Thomas Monjalon <thomas@monjalon.net>
> > 08/07/2020 14:05, Zhang, Qi Z:
> > > From: Thomas Monjalon <thomas@monjalon.net>
> > > > 08/07/2020 13:10, Zhang, Qi Z:
> > > > > From: Thomas Monjalon <thomas@monjalon.net>
> > > > > > 08/07/2020 11:45, Zhang, Qi Z:
> > > > > > > On 2020/7/7 19:06, Thomas Monjalon wrote:
> > > > > > > > 16/06/2020 10:16, Junfeng Guo:
> > > > > > > >> This patch defines new RSS offload types for IPv6 prefix
> > > > > > > >> with 32, 48,
> > > > > > > >> 64 bits of both SRC and DST IPv6 address.
> > > > > > > >>
> > > > > > > >> Signed-off-by: Junfeng Guo <junfeng.guo@intel.com>
> > > > > > > >> ---
> > > > > > > >>   lib/librte_ethdev/rte_ethdev.h | 51
> > > > > > ++++++++++++++++++++++++++++++++++
> > > > > > > >>   1 file changed, 51 insertions(+)
> > > > > > > >>
> > > > > > > >> diff --git a/lib/librte_ethdev/rte_ethdev.h
> > > > > > > >> b/lib/librte_ethdev/rte_ethdev.h index 631b146bd..5a7ba36d8
> > > > > > > >> 100644
> > > > > > > >> --- a/lib/librte_ethdev/rte_ethdev.h
> > > > > > > >> +++ b/lib/librte_ethdev/rte_ethdev.h
> > > > > > > >> @@ -538,6 +538,9 @@ struct rte_eth_rss_conf {
> > > > > > > >>   #define ETH_RSS_L4_DST_ONLY        (1ULL << 60)
> > > > > > > >>   #define ETH_RSS_L2_SRC_ONLY        (1ULL << 59)
> > > > > > > >>   #define ETH_RSS_L2_DST_ONLY        (1ULL << 58)
> > > > > > > >> +#define ETH_RSS_L3_PRE32           (1ULL << 57)
> > > > > > > >> +#define ETH_RSS_L3_PRE48           (1ULL << 56)
> > > > > > > >> +#define ETH_RSS_L3_PRE64           (1ULL << 55)
> > > > > > > >
> > > > > > > > PRE32, 48 and 64 are not obvious.
> > > > > > > > Why is it needed?
> > > > > > >
> > > > > > > there is typical usage for NAT64, which use 32 bit prefix for
> > > > > > > IPv6 addresses, in this case flows over IPv4 and IPv6 will
> > > > > > > result in the same hash value, as well as 48, 64, which also
> > > > > > > have some corresponding use cases,
> > > > > > > > At least, please add comments for the values of this API.
> > > > > > >
> > > > > > > sure, we will add more comments.
> > [...]
> > > > > > > 32, 48, 64 are typical usage, and consider suffix pair we may
> > > > > > > add later, it will cost 6 bits so far we still have 27 bit
> > > > > > > left,  so it looks like will not be a problem in following couple
> > releases.
> > > > > >
> > > > > > Having some space left is not a reason to waste it :) If I
> > > > > > understand well, there is no standard for this API.
> > > > > > You are assigning some bits to some usage.
> > > > > > I don't find it generic and flexible enough.
> > > > >
> > > > > Actually IPv6 address prefix is in spec, please check below RFC.
> > > > > https://tools.ietf.org/html/rfc6052#page-5
> > > >
> > > > Quoting the RFC:
> > > > "
> > > >    the prefix shall be either the "Well-Known Prefix"
> > > >    or a "Network-Specific Prefix" unique to the organization
> > > >    deploying the address translators.
> > > >    The prefixes can only have one of the following lengths:
> > > >    32, 40, 48, 56, 64, or 96.
> > > >    (The Well-Known Prefix is 96 bits long, and can only be used
> > > >    in the last form of the table.)
> > > > "
> > > >
> > > > So 40 and 56 are missing.
> > >
> > > Yes, like to add and lets accelerate the progress to abandon the old
> > > APIs :)
> > 
> > Please could list which part of the existing API you would like to deprecate in
> > future?
> 
> I think it's a new version of rte_flow_action_rss, we need a more generic way to describe the RSS input set of a flow
> But not just a 64 bits type, then all ETH_RSS_xxx will be decoupled from rte_flow.

I was asking what would you deprecate?