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Message-Id: <20251104134033.344807-6-dolinux.peng@gmail.com>
Date: Tue, 4 Nov 2025 21:40:31 +0800
From: Donglin Peng <dolinux.peng@...il.com>
To: ast@...nel.org
Cc: linux-kernel@...r.kernel.org,
bpf@...r.kernel.org,
Donglin Peng <dolinux.peng@...il.com>,
Eduard Zingerman <eddyz87@...il.com>,
Andrii Nakryiko <andrii.nakryiko@...il.com>,
Alan Maguire <alan.maguire@...cle.com>,
Song Liu <song@...nel.org>,
pengdonglin <pengdonglin@...omi.com>
Subject: [RFC PATCH v4 5/7] btf: Optimize type lookup with binary search
From: pengdonglin <pengdonglin@...omi.com>
Improve btf_find_by_name_kind() performance by adding binary search
support for sorted types. Falls back to linear search for compatibility.
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: Song Liu <song@...nel.org>
Signed-off-by: pengdonglin <pengdonglin@...omi.com>
Signed-off-by: Donglin Peng <dolinux.peng@...il.com>
---
kernel/bpf/btf.c | 111 ++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 101 insertions(+), 10 deletions(-)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 0de8fc8a0e0b..da35d8636b9b 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -259,6 +259,7 @@ struct btf {
void *nohdr_data;
struct btf_header hdr;
u32 nr_types; /* includes VOID for base BTF */
+ u32 nr_sorted_types; /* exclude VOID for base BTF */
u32 types_size;
u32 data_size;
refcount_t refcnt;
@@ -494,6 +495,11 @@ static bool btf_type_is_modifier(const struct btf_type *t)
return false;
}
+static int btf_start_id(const struct btf *btf)
+{
+ return btf->start_id + (btf->base_btf ? 0 : 1);
+}
+
bool btf_type_is_void(const struct btf_type *t)
{
return t == &btf_void;
@@ -544,24 +550,109 @@ u32 btf_nr_types(const struct btf *btf)
return total;
}
-s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind)
+/* 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_by_name_kind_bsearch(const struct btf *btf, const char *name,
+ s32 *left, s32 *right)
{
const struct btf_type *t;
const char *tname;
- u32 i, total;
+ s32 l, r, m, lmost, rmost;
+ int ret;
- total = btf_nr_types(btf);
- for (i = 1; i < total; i++) {
- t = btf_type_by_id(btf, i);
- if (BTF_INFO_KIND(t->info) != kind)
- continue;
+ /* found the leftmost btf_type that matches */
+ l = *left;
+ r = *right;
+ lmost = -1;
+ while (l <= r) {
+ m = l + (r - l) / 2;
+ t = btf_type_by_id(btf, m);
+ tname = btf_name_by_offset(btf, t->name_off);
+ ret = strcmp(tname, name);
+ if (ret < 0) {
+ l = m + 1;
+ } else {
+ if (ret == 0)
+ lmost = m;
+ r = m - 1;
+ }
+ }
+ if (lmost == -1)
+ return -ENOENT;
+
+ /* found the rightmost btf_type that matches */
+ l = lmost;
+ r = *right;
+ rmost = -1;
+ while (l <= r) {
+ m = l + (r - l) / 2;
+ t = btf_type_by_id(btf, m);
tname = btf_name_by_offset(btf, t->name_off);
- if (!strcmp(tname, name))
- return i;
+ ret = strcmp(tname, name);
+ if (ret <= 0) {
+ if (ret == 0)
+ rmost = m;
+ l = m + 1;
+ } else {
+ r = m - 1;
+ }
}
- return -ENOENT;
+ *left = lmost;
+ *right = rmost;
+ return lmost;
+}
+
+s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind)
+{
+ const struct btf *base_btf = btf_base_btf(btf);;
+ const struct btf_type *t;
+ const char *tname;
+ int err = -ENOENT;
+
+ if (base_btf)
+ err = btf_find_by_name_kind(base_btf, name, kind);
+
+ if (err == -ENOENT) {
+ if (btf->nr_sorted_types) {
+ /* binary search */
+ s32 l, r;
+ int ret;
+
+ l = btf_start_id(btf);
+ r = l + btf->nr_sorted_types - 1;
+ ret = btf_find_by_name_kind_bsearch(btf, name, &l, &r);
+ if (ret < 0)
+ goto out;
+ /* found the leftmost btf_type that matches */
+ while (l <= r) {
+ t = btf_type_by_id(btf, l);
+ if (BTF_INFO_KIND(t->info) == kind)
+ return l;
+ l++;
+ }
+ } else {
+ /* linear search */
+ u32 i, total;
+
+ total = btf_nr_types(btf);
+ for (i = btf_start_id(btf); i < total; i++) {
+ t = btf_type_by_id(btf, i);
+ if (BTF_INFO_KIND(t->info) != kind)
+ continue;
+
+ tname = btf_name_by_offset(btf, t->name_off);
+ if (!strcmp(tname, name))
+ return i;
+ }
+ }
+ }
+
+out:
+ return err;
}
s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)
--
2.34.1
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