[PATCH bpf-next v10 10/13] libbpf: Optimize the performance of determine_ptr_size

Donglin Peng posted 13 patches 1 day ago
[PATCH bpf-next v10 10/13] libbpf: Optimize the performance of determine_ptr_size
Posted by Donglin Peng 1 day ago
From: pengdonglin <pengdonglin@xiaomi.com>

Leverage the performance improvement of btf__find_by_name_kind() when
BTF is sorted. For sorted BTF, the function uses binary search with
O(log n) complexity instead of linear search, providing significant
performance benefits, especially for large BTF like vmlinux.

Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Ihor Solodrai <ihor.solodrai@linux.dev>
Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
---
 tools/lib/bpf/btf.c | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index c63d46b7d74b..b5b0898d033d 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -659,29 +659,21 @@ static int determine_ptr_size(const struct btf *btf)
 		"int long unsigned",
 	};
 	const struct btf_type *t;
-	const char *name;
-	int i, j, n;
+	int i, id;
 
 	if (btf->base_btf && btf->base_btf->ptr_sz > 0)
 		return btf->base_btf->ptr_sz;
 
-	n = btf__type_cnt(btf);
-	for (i = 1; i < n; i++) {
-		t = btf__type_by_id(btf, i);
-		if (!btf_is_int(t))
+	for (i = 0; i < ARRAY_SIZE(long_aliases); i++) {
+		id = btf__find_by_name_kind(btf, long_aliases[i], BTF_KIND_INT);
+		if (id < 0)
 			continue;
 
+		t = btf__type_by_id(btf, id);
 		if (t->size != 4 && t->size != 8)
 			continue;
 
-		name = btf__name_by_offset(btf, t->name_off);
-		if (!name)
-			continue;
-
-		for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
-			if (strcmp(name, long_aliases[j]) == 0)
-				return t->size;
-		}
+		return t->size;
 	}
 
 	return -1;
-- 
2.34.1
Re: [PATCH bpf-next v10 10/13] libbpf: Optimize the performance of determine_ptr_size
Posted by Andrii Nakryiko 11 hours ago
On Thu, Dec 18, 2025 at 3:31 AM Donglin Peng <dolinux.peng@gmail.com> wrote:
>
> From: pengdonglin <pengdonglin@xiaomi.com>
>
> Leverage the performance improvement of btf__find_by_name_kind() when
> BTF is sorted. For sorted BTF, the function uses binary search with
> O(log n) complexity instead of linear search, providing significant
> performance benefits, especially for large BTF like vmlinux.
>
> Cc: Eduard Zingerman <eddyz87@gmail.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> Cc: Alan Maguire <alan.maguire@oracle.com>
> Cc: Ihor Solodrai <ihor.solodrai@linux.dev>
> Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
> Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
> ---
>  tools/lib/bpf/btf.c | 20 ++++++--------------
>  1 file changed, 6 insertions(+), 14 deletions(-)
>

nice and clean

Acked-by: Andrii Nakryiko <andrii@kernel.org>

> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index c63d46b7d74b..b5b0898d033d 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -659,29 +659,21 @@ static int determine_ptr_size(const struct btf *btf)
>                 "int long unsigned",
>         };
>         const struct btf_type *t;
> -       const char *name;
> -       int i, j, n;
> +       int i, id;
>
>         if (btf->base_btf && btf->base_btf->ptr_sz > 0)
>                 return btf->base_btf->ptr_sz;
>
> -       n = btf__type_cnt(btf);
> -       for (i = 1; i < n; i++) {
> -               t = btf__type_by_id(btf, i);
> -               if (!btf_is_int(t))
> +       for (i = 0; i < ARRAY_SIZE(long_aliases); i++) {
> +               id = btf__find_by_name_kind(btf, long_aliases[i], BTF_KIND_INT);
> +               if (id < 0)
>                         continue;
>
> +               t = btf__type_by_id(btf, id);
>                 if (t->size != 4 && t->size != 8)
>                         continue;
>
> -               name = btf__name_by_offset(btf, t->name_off);
> -               if (!name)
> -                       continue;
> -
> -               for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
> -                       if (strcmp(name, long_aliases[j]) == 0)
> -                               return t->size;
> -               }
> +               return t->size;
>         }
>
>         return -1;
> --
> 2.34.1
>
Re: [PATCH bpf-next v10 10/13] libbpf: Optimize the performance of determine_ptr_size
Posted by Donglin Peng 6 hours ago
On Fri, Dec 19, 2025 at 8:03 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Thu, Dec 18, 2025 at 3:31 AM Donglin Peng <dolinux.peng@gmail.com> wrote:
> >
> > From: pengdonglin <pengdonglin@xiaomi.com>
> >
> > Leverage the performance improvement of btf__find_by_name_kind() when
> > BTF is sorted. For sorted BTF, the function uses binary search with
> > O(log n) complexity instead of linear search, providing significant
> > performance benefits, especially for large BTF like vmlinux.
> >
> > Cc: Eduard Zingerman <eddyz87@gmail.com>
> > Cc: Alexei Starovoitov <ast@kernel.org>
> > Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> > Cc: Alan Maguire <alan.maguire@oracle.com>
> > Cc: Ihor Solodrai <ihor.solodrai@linux.dev>
> > Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
> > Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
> > ---
> >  tools/lib/bpf/btf.c | 20 ++++++--------------
> >  1 file changed, 6 insertions(+), 14 deletions(-)
> >
>
> nice and clean

Thank you.

>
> Acked-by: Andrii Nakryiko <andrii@kernel.org>
>
> > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> > index c63d46b7d74b..b5b0898d033d 100644
> > --- a/tools/lib/bpf/btf.c
> > +++ b/tools/lib/bpf/btf.c
> > @@ -659,29 +659,21 @@ static int determine_ptr_size(const struct btf *btf)
> >                 "int long unsigned",
> >         };
> >         const struct btf_type *t;
> > -       const char *name;
> > -       int i, j, n;
> > +       int i, id;
> >
> >         if (btf->base_btf && btf->base_btf->ptr_sz > 0)
> >                 return btf->base_btf->ptr_sz;
> >
> > -       n = btf__type_cnt(btf);
> > -       for (i = 1; i < n; i++) {
> > -               t = btf__type_by_id(btf, i);
> > -               if (!btf_is_int(t))
> > +       for (i = 0; i < ARRAY_SIZE(long_aliases); i++) {
> > +               id = btf__find_by_name_kind(btf, long_aliases[i], BTF_KIND_INT);
> > +               if (id < 0)
> >                         continue;
> >
> > +               t = btf__type_by_id(btf, id);
> >                 if (t->size != 4 && t->size != 8)
> >                         continue;
> >
> > -               name = btf__name_by_offset(btf, t->name_off);
> > -               if (!name)
> > -                       continue;
> > -
> > -               for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
> > -                       if (strcmp(name, long_aliases[j]) == 0)
> > -                               return t->size;
> > -               }
> > +               return t->size;
> >         }
> >
> >         return -1;
> > --
> > 2.34.1
> >
Re: [PATCH bpf-next v10 10/13] libbpf: Optimize the performance of determine_ptr_size
Posted by Eduard Zingerman 13 hours ago
On Thu, 2025-12-18 at 19:30 +0800, Donglin Peng wrote:
> From: pengdonglin <pengdonglin@xiaomi.com>
> 
> Leverage the performance improvement of btf__find_by_name_kind() when
> BTF is sorted. For sorted BTF, the function uses binary search with
> O(log n) complexity instead of linear search, providing significant
> performance benefits, especially for large BTF like vmlinux.
> 
> Cc: Eduard Zingerman <eddyz87@gmail.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> Cc: Alan Maguire <alan.maguire@oracle.com>
> Cc: Ihor Solodrai <ihor.solodrai@linux.dev>
> Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
> Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

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