netdev - Re: [RFC PATCH 03/13] nexthop: Add netlink defines and enumerators for resilient NH groups

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Message-ID: <20210213201758.GB401513@shredder.lan>
Date:   Sat, 13 Feb 2021 22:17:58 +0200
From:   Ido Schimmel <idosch@...sch.org>
To:     David Ahern <dsahern@...il.com>
Cc:     Petr Machata <petrm@...dia.com>, netdev@...r.kernel.org,
        David Ahern <dsahern@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Ido Schimmel <idosch@...dia.com>
Subject: Re: [RFC PATCH 03/13] nexthop: Add netlink defines and enumerators
 for resilient NH groups

On Sat, Feb 13, 2021 at 12:16:45PM -0700, David Ahern wrote:
> On 2/8/21 1:42 PM, Petr Machata wrote:
> > @@ -52,8 +53,50 @@ enum {
> >  	NHA_FDB,	/* flag; nexthop belongs to a bridge fdb */
> >  	/* if NHA_FDB is added, OIF, BLACKHOLE, ENCAP cannot be set */
> >  
> > +	/* nested; resilient nexthop group attributes */
> > +	NHA_RES_GROUP,
> > +	/* nested; nexthop bucket attributes */
> > +	NHA_RES_BUCKET,
> > +
> >  	__NHA_MAX,
> >  };
> >  
> >  #define NHA_MAX	(__NHA_MAX - 1)
> > +
> > +enum {
> > +	NHA_RES_GROUP_UNSPEC,
> > +	/* Pad attribute for 64-bit alignment. */
> > +	NHA_RES_GROUP_PAD = NHA_RES_GROUP_UNSPEC,
> > +
> > +	/* u32; number of nexthop buckets in a resilient nexthop group */
> > +	NHA_RES_GROUP_BUCKETS,
> 
> u32 is overkill; arguably u16 (64k) should be more than enough buckets
> for any real use case.

We wanted to make it future-proof, but I think we can live with 64k. At
least in Spectrum the maximum is 4k. I don't know about other devices,
but I guess it is not more than 64k.