Re: [PATCH bpf-next v10 08/13] bpf: Skip anonymous types in type lookup for performance

[Eduard Zingerman]

On Thu, 2025-12-18 at 19:30 +0800, Donglin Peng wrote:
> From: pengdonglin <pengdonglin@xxxxxxxxxx>
> 
> Currently, vmlinux and kernel module BTFs are unconditionally
> sorted during the build phase, with named types placed at the
> end. Thus, anonymous types should be skipped when starting the
> search. In my vmlinux BTF, the number of anonymous types is
> 61,747, which means the loop count can be reduced by 61,747.
> 
> Cc: Eduard Zingerman <eddyz87@xxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> Cc: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx>
> Cc: Alan Maguire <alan.maguire@xxxxxxxxxx>
> Cc: Ihor Solodrai <ihor.solodrai@xxxxxxxxx>
> Cc: Xiaoqin Zhang <zhangxiaoqin@xxxxxxxxxx>
> Signed-off-by: pengdonglin <pengdonglin@xxxxxxxxxx>
> ---

Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>

>  include/linux/btf.h   |  1 +
>  kernel/bpf/btf.c      | 24 ++++++++++++++++++++----
>  kernel/bpf/verifier.c |  7 +------
>  3 files changed, 22 insertions(+), 10 deletions(-)
> 
> diff --git a/include/linux/btf.h b/include/linux/btf.h
> index f06976ffb63f..2d28f2b22ae5 100644
> --- a/include/linux/btf.h
> +++ b/include/linux/btf.h
> @@ -220,6 +220,7 @@ bool btf_is_module(const struct btf *btf);
>  bool btf_is_vmlinux(const struct btf *btf);
>  struct module *btf_try_get_module(const struct btf *btf);
>  u32 btf_nr_types(const struct btf *btf);
> +u32 btf_sorted_start_id(const struct btf *btf);
>  struct btf *btf_base_btf(const struct btf *btf);
>  bool btf_type_is_i32(const struct btf_type *t);
>  bool btf_type_is_i64(const struct btf_type *t);
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index a9e2345558c0..3aeb4f00cbfe 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -550,6 +550,11 @@ u32 btf_nr_types(const struct btf *btf)
>  	return total;
>  }
>  
> +u32 btf_sorted_start_id(const struct btf *btf)

Nit: the name is a bit confusing, given that it not always returns the
     start id for sorted part. btf_maybe_first_named_id?
     Can't figure out a good name :(

> +{
> +	return btf->sorted_start_id ?: (btf->start_id ?: 1);
> +}
> +
>  /*
>   * Assuming that types are sorted by name in ascending order.
>   */

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