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Thu, 18 Dec 2025 03:31:10 -0800 (PST) Received: from pengdl-pc.mioffice.cn ([43.224.245.249]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-34e70d4f887sm2328237a91.3.2025.12.18.03.31.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Dec 2025 03:31:09 -0800 (PST) From: Donglin Peng To: ast@kernel.org, andrii.nakryiko@gmail.com, eddyz87@gmail.com Cc: zhangxiaoqin@xiaomi.com, ihor.solodrai@linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, pengdonglin Subject: [PATCH bpf-next v10 00/13] Improve the performance of BTF type lookups with binary search Date: Thu, 18 Dec 2025 19:30:38 +0800 Message-Id: <20251218113051.455293-1-dolinux.peng@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: pengdonglin The series addresses the performance limitations of linear search in large BTFs by: 1. Adding BTF permutation support 2. Using resolve_btfids to sort BTF during the build phase 3. Checking BTF sorting 4. Using binary search when looking up types Patch #1 introduces an interface for btf__permute in libbpf to relay out BTF. Patch #2 adds test cases to validate the functionality of btf__permute in base and split BTF scenarios. Patch #3 introduces a new phase in the resolve_btfids tool to sort BTF by name in ascending order. Patches #4-#7 implement the sorting check and binary search. Patches #8-#10 optimize type lookup performance of some functions by skipping anonymous types or invoking btf_find_by_name_kind. Patches #11-#12 introduce btf_is_sorted and btf_sorted_start_id for clarity. Patch #13 refactors the code by calling str_is_empty. Here is a simple performance test result [1] for lookups to find 87,584 named types in vmlinux BTF: ./vmtest.sh -- ./test_progs -t btf_permute/perf -v Results: | Condition | Lookup Time | Improvement | |--------------------|-------------|--------------| | Unsorted (Linear) | 36,534 ms | Baseline | | Sorted (Binary) | 15 ms | 2437x faster | The binary search implementation reduces lookup time from 36.5 seconds to 15 milliseconds, achieving a **2437x** speedup for large-scale type queries. Changelog: v10: - Improve btf__permute() documentation (Eduard) - Fall back to linear search when locating anonymous types (Eduard) - Remove redundant NULL name check in libbpf's linear search path (Eduard) - Simplify btf_check_sorted() implementation (Eduard) - Treat kernel modules as unsorted by default - Introduce btf_is_sorted and btf_sorted_start_id for clarity (Eduard) - Fix optimizations in btf_find_decl_tag_value() and btf_prepare_func_args() to support split BTF - Remove linear search branch in determine_ptr_size() - Rebase onto Ihor's v4 patch series [4] v9: - Link: https://lore.kernel.org/bpf/20251208062353.1702672-1-dolinux.peng@gmail.com/ - Optimize the performance of the function determine_ptr_size by invoking btf__find_by_name_kind - Optimize the performance of btf_find_decl_tag_value/btf_prepare_func_args/ bpf_core_add_cands by skipping anonymous types - Rebase the patch series onto Ihor's v3 patch series [3] v8 - Link: https://lore.kernel.org/bpf/20251126085025.784288-1-dolinux.peng@gmail.com/ - Remove the type dropping feature of btf__permute (Andrii) - Refactor the code of btf__permute (Andrii, Eduard) - Make the self-test code cleaner (Eduard) - Reconstruct the BTF sorting patch based on Ihor's patch series [2] - Simplify the sorting logic and place anonymous types before named types (Andrii, Eduard) - Optimize type lookup performance of two kernel functions - Refactoring the binary search and type lookup logic achieves a 4.2% performance gain, reducing the average lookup time (via the perf test code in [1] for 60,995 named types in vmlinux BTF) from 10,217 us (v7) to 9,783 us (v8). v7: - Link: https://lore.kernel.org/all/20251119031531.1817099-1-dolinux.peng@gmail.com/ - btf__permute API refinement: Adjusted id_map and id_map_cnt parameter usage so that for base BTF, id_map[0] now contains the new id of original type id 1 (instead of VOID type id 0), improving logical consistency - Selftest updates: Modified test cases to align with the API usage changes - Refactor the code of resolve_btfids v6: - Link: https://lore.kernel.org/all/20251117132623.3807094-1-dolinux.peng@gmail.com/ - ID Map-based reimplementation of btf__permute (Andrii) - Build-time BTF sorting using resolve_btfids (Alexei, Eduard) - Binary search method refactoring (Andrii) - Enhanced selftest coverage v5: - Link: https://lore.kernel.org/all/20251106131956.1222864-1-dolinux.peng@gmail.com/ - Refactor binary search implementation for improved efficiency (Thanks to Andrii and Eduard) - Extend btf__permute interface with 'ids_sz' parameter to support type dropping feature (suggested by Andrii). Plan subsequent reimplementation of id_map version for comparative analysis with current sequence interface - Add comprehensive test coverage for type dropping functionality - Enhance function comment clarity and accuracy v4: - Link: https://lore.kernel.org/all/20251104134033.344807-1-dolinux.peng@gmail.com/ - Abstracted btf_dedup_remap_types logic into a helper function (suggested by Eduard). - Removed btf_sort.c and implemented sorting separately for libbpf and kernel (suggested by Andrii). - Added test cases for both base BTF and split BTF scenarios (suggested by Eduard). - Added validation for name-only sorting of types (suggested by Andrii) - Refactored btf__permute implementation to reduce complexity (suggested by Andrii) - Add doc comments for btf__permute (suggested by Andrii) v3: - Link: https://lore.kernel.org/all/20251027135423.3098490-1-dolinux.peng@gmail.com/ - Remove sorting logic from libbpf and provide a generic btf__permute() interface (suggested by Andrii) - Omitted the search direction patch to avoid conflicts with base BTF (suggested by Eduard). - Include btf_sort.c directly in btf.c to reduce function call overhead v2: - Link: https://lore.kernel.org/all/20251020093941.548058-1-dolinux.peng@gmail.com/ - Moved sorting to the build phase to reduce overhead (suggested by Alexei). - Integrated sorting into btf_dedup_compact_and_sort_types (suggested by Eduard). - Added sorting checks during BTF parsing. - Consolidated common logic into btf_sort.c for sharing (suggested by Alan). v1: - Link: https://lore.kernel.org/all/20251013131537.1927035-1-dolinux.peng@gmail.com/ [1] https://github.com/pengdonglin137/btf_sort_test [2] https://lore.kernel.org/bpf/20251126012656.3546071-1-ihor.solodrai@linux.dev/ [3] https://lore.kernel.org/bpf/20251205223046.4155870-1-ihor.solodrai@linux.dev/ [4] https://lore.kernel.org/bpf/20251218003314.260269-1-ihor.solodrai@linux.dev/ pengdonglin (13): libbpf: Add BTF permutation support for type reordering selftests/bpf: Add test cases for btf__permute functionality tools/resolve_btfids: Support BTF sorting feature libbpf: Optimize type lookup with binary search for sorted BTF libbpf: Verify BTF Sorting btf: Optimize type lookup with binary search btf: Verify BTF Sorting bpf: Skip anonymous types in type lookup for performance bpf: Optimize the performance of find_bpffs_btf_enums libbpf: Optimize the performance of determine_ptr_size libbpf: Add btf_is_sorted and btf_sorted_start_id helpers to refactor the code btf: Add btf_is_sorted to refactor the code btf: Refactor the code by calling str_is_empty include/linux/btf.h | 2 + kernel/bpf/btf.c | 170 +++++++++- kernel/bpf/inode.c | 42 ++- kernel/bpf/verifier.c | 7 +- tools/bpf/resolve_btfids/main.c | 68 ++++ tools/lib/bpf/btf.c | 321 +++++++++++++++--- tools/lib/bpf/btf.h | 36 ++ tools/lib/bpf/libbpf.c | 4 +- tools/lib/bpf/libbpf.map | 1 + tools/lib/bpf/libbpf_internal.h | 2 + .../selftests/bpf/prog_tests/btf_permute.c | 228 +++++++++++++ 11 files changed, 786 insertions(+), 95 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/btf_permute.c -- 2.34.1