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Mon, 20 Oct 2025 02:39:51 -0700 (PDT) From: Donglin Peng To: ast@kernel.org Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Donglin Peng , Eduard Zingerman , Andrii Nakryiko , Alan Maguire , Song Liu , pengdonglin Subject: [RFC PATCH v2 1/5] btf: search local BTF before base BTF Date: Mon, 20 Oct 2025 17:39:37 +0800 Message-Id: <20251020093941.548058-2-dolinux.peng@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20251020093941.548058-1-dolinux.peng@gmail.com> References: <20251020093941.548058-1-dolinux.peng@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Change btf_find_by_name_kind() to search the local BTF first, then fall back to the base BTF. This can skip traversing the large vmlinux BTF when the target type resides in a kernel module's BTF, thereby significantly improving lookup performance. In a test searching for the btf_type of function ext2_new_inode located in the ext2 kernel module: Before: 408631 ns After: 499 ns Performance improvement: ~819x faster Cc: Eduard Zingerman Cc: Alexei Starovoitov Cc: Andrii Nakryiko Cc: Alan Maguire Cc: Song Liu Signed-off-by: pengdonglin Signed-off-by: Donglin Peng --- include/linux/btf.h | 1 + kernel/bpf/btf.c | 27 ++++++++++++++++++--------- 2 files changed, 19 insertions(+), 9 deletions(-) diff --git a/include/linux/btf.h b/include/linux/btf.h index f06976ffb63f..ddc53a7ac7cd 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_type_cnt(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 0de8fc8a0e0b..c414cf37e1bd 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -544,22 +544,31 @@ u32 btf_nr_types(const struct btf *btf) return total; } +u32 btf_type_cnt(const struct btf *btf) +{ + return btf->start_id + btf->nr_types; +} + s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind) { const struct btf_type *t; const char *tname; u32 i, total; - 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; + do { + total = btf_type_cnt(btf); + for (i = btf->start_id; 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; - } + tname = btf_name_by_offset(btf, t->name_off); + if (!strcmp(tname, name)) + return i; + } + + btf = btf->base_btf; + } while (btf); return -ENOENT; } -- 2.34.1