[Babel-users] hmac merge

[Dave Taht]

On Mon, Nov 12, 2018 at 5:18 PM Dave Taht <dave.taht at gmail.com> wrote:
>
> On Mon, Nov 12, 2018 at 5:06 PM Juliusz Chroboczek <jch at irif.fr> wrote:
> >
> > >> Yeah, we should just include an implementation of SHA-256 in the code.
> >
> > > There's also the option...
> >
> > Given that the main selling point of HMAC vs. DTLS is that it has no
> > dependencies, it wouldn't be particularly wise to make the reference
> > implementation depend on a Linux-specific library.
> >
> > Of course, we'll make it easy for distributors to replace our bundled
> > implementation of SHA-256 with whatever it is they find convenient.  (I
> > expect Dave to replace it with his hand-written implementation that
> > interleaves MMX with AVX2 while simultaneously performing modular
> > multiplication in the U pipe to hash 27.7 bytes per cycle per core.)
> >
> > (If you know what the U pipe is, you're old.)
>
> I haven't had fun like that in ages! :) And you forgot that you can
> still use the old FPU stack for stuff, if you are careful.

oops, I misread what you said. Still, that 80 bit FP precision must be
useful for something.

Why can't we re-calc metrics in floating point using SSE or AVX? Look
at all these "shorts"!
to heck with integer arithmetic!

struct babel_route {
    struct source *src;
    unsigned short refmetric;
    unsigned short cost;
    unsigned short add_metric;
    unsigned short seqno;
    struct neighbour *neigh;
    unsigned char nexthop[16];
    time_t time;
    unsigned short hold_time;    /* in seconds */
    unsigned short smoothed_metric; /* for route selection */


/me passes jules back the vodka

>
> But I'd rather see babel scale past 64k routes, and I really have come
> to understand that it's algorithmic first, asm tweaks second.
>
> >
> > -- Juliusz
> >
> > _______________________________________________
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> > https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/babel-users
>
>
>
> --
>
> Dave Täht
> CTO, TekLibre, LLC
> http://www.teklibre.com
> Tel: 1-831-205-9740



-- 

Dave Täht
CTO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-831-205-9740