Hi David,
On Tue, Jan 09, 2018 at 08:48:37PM -0700, David Ahern wrote:
> On 1/9/18 7:40 AM, Ido Schimmel wrote:
> > The use of hash-threshold instead of modulo-N makes it trivial to add
> > support for non-equal-cost multipath.
> >
> > Instead of dividing the multipath hash function's output space equally
> > between the nexthops, each nexthop is assigned a region size which is
> > proportional to its weight.
> >
> > Signed-off-by: Ido Schimmel <ido...@mellanox.com>
> > ---
> > include/net/ip6_fib.h | 1 +
> > net/ipv6/route.c | 11 +++++++----
> > 2 files changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
> > index 97cd05d87780..34ec321d6a03 100644
> > --- a/include/net/ip6_fib.h
> > +++ b/include/net/ip6_fib.h
> > @@ -171,6 +171,7 @@ struct rt6_info {
> > u32 rt6i_metric;
> > u32 rt6i_pmtu;
> > /* more non-fragment space at head required */
> > + int rt6i_nh_weight;
> > unsigned short rt6i_nfheader_len;
> > u8 rt6i_protocol;
> > u8 exception_bucket_flushed:1,
>
> Since dst is cacheline aligned there is a hole after rt6i_nh_flags. In
> patch 1 you put rt6i_nh_upper_bound in that hole. Putting the weight
> there too keeps those variables together as well as using the open space.
Before patch 1 there's a hole of 4 bytes after rt6i_nh_flags which I use
for rt6i_nh_upper_bound. If I put rt6i_nh_weight there as well, then I
create a 60 bytes hole because the dst needs to be cached aligned.
Since rt6i_nh_weight isn't used in fast-path, I just put it at the end.
