Re: [RFC PATCH v4 3/7] libbpf: Optimize type lookup with binary search for sorted BTF

[Andrii Nakryiko]

On Tue, Nov 4, 2025 at 4:19 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> On Tue, 2025-11-04 at 16:11 -0800, Andrii Nakryiko wrote:
>
> [...]
>
> > > @@ -897,44 +903,134 @@ int btf__resolve_type(const struct btf *btf, __u32 type_id)
> > >         return type_id;
> > >  }
> > >
> > > -__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
> > > +/*
> > > + * Find BTF types with matching names within the [left, right] index range.
> > > + * On success, updates *left and *right to the boundaries of the matching range
> > > + * and returns the leftmost matching index.
> > > + */
> > > +static __s32 btf_find_type_by_name_bsearch(const struct btf *btf, const char *name,
> > > +                                               __s32 *left, __s32 *right)
> >
> > I thought we discussed this, why do you need "right"? Two binary
> > searches where one would do just fine.
>
> I think the idea is that there would be less strcmp's if there is a
> long sequence of items with identical names.

Sure, it's a tradeoff. But how long is the set of duplicate name
entries we expect in kernel BTF? Additional O(logN) over 70K+ types
with high likelihood will take more comparisons.