Re: [PATCH v2 3/3] Optimize route dependency solver.

[Stefano Brivio <sbrivio@redhat.com>]

On Sat, 19 Sep 2026 14:56:56 +0200
Martin Schitter <ms+git@mur.at> wrote:

> On 9/17/26 21:08, Stefano Brivio wrote:
> >> Never make more resolution attempts than there are still unresolved
> >> dependency errors.
> >>
> >> In the context of my current mesh network with ~700 route entries
> >> these changes reduce the required processing time from 5.5s to 15ms.  
> > 
> > Ouch. Nice.  
> 
> After searching for answers, how these ENETUNREACH and EHOSTUNREACH in 
> the dependency solver routines are actually caused, I finally looked 
> into the iproute2 code for the save and restore commands:
> 
> https://github.com/iproute2/iproute2/blob/e6471d772f3e15a813e6c9a81b4b7adcfad22899/ip/iproute.c#L2314
> 
> Now I finally see that this task can be handled without all this stupid 
> trial-and-error play and doesn't require a limit of route entries if we 
> just reassemble the routing tables in three successive steps resp. loops:
> 
> /* Restore routes in correct order:
>   * 0. ones for local addresses,
>   * 1. ones for local networks,
>   * 2. others (remote networks/hosts).
>   */

Just a quick comment before you risk losing a lot of time (I'm really
not sure though): there *might* be interdependencies between routes in
1. and between routes in 2., especially with 'nexthop' objects. And
IPv6 has several scopes. Maybe it all works thought, I haven't checked
your iproute reference yet.

-- 
Stefano