linux-kernel - [PATCH bpf-next v9 10/10] libbpf: Optimize the performance of determine_ptr

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Message-Id: <20251208062353.1702672-11-dolinux.peng@gmail.com>
Date: Mon,  8 Dec 2025 14:23:53 +0800
From: Donglin Peng <dolinux.peng@...il.com>
To: ast@...nel.org,
	andrii.nakryiko@...il.com
Cc: eddyz87@...il.com,
	zhangxiaoqin@...omi.com,
	ihor.solodrai@...ux.dev,
	linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org,
	pengdonglin <pengdonglin@...omi.com>,
	Alan Maguire <alan.maguire@...cle.com>
Subject: [PATCH bpf-next v9 10/10] libbpf: Optimize the performance of determine_ptr_size

From: pengdonglin <pengdonglin@...omi.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@...il.com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Alan Maguire <alan.maguire@...cle.com>
Cc: Ihor Solodrai <ihor.solodrai@...ux.dev>
Cc: Xiaoqin Zhang <zhangxiaoqin@...omi.com>
Signed-off-by: pengdonglin <pengdonglin@...omi.com>
---
 tools/lib/bpf/btf.c | 42 ++++++++++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 14 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index a53d24704857..6de09a5c4334 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -660,27 +660,41 @@ static int determine_ptr_size(const struct btf *btf)
 	};
 	const struct btf_type *t;
 	const char *name;
-	int i, j, n;
+	int i, j, n, 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))
-			continue;
+	if (btf->sorted_start_id > 0) {
+		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;
 
-		if (t->size != 4 && t->size != 8)
-			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;
+			return t->size;
+		}
+	} else {
+		n = btf__type_cnt(btf);
+		for (i = 1; i < n; i++) {
+			t = btf__type_by_id(btf, i);
+			if (!btf_is_int(t))
+				continue;
+
+			if (t->size != 4 && t->size != 8)
+				continue;
 
-		for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
-			if (strcmp(name, long_aliases[j]) == 0)
-				return t->size;
+			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;
+			}
 		}
 	}
 
-- 
2.34.1