Messages in this thread |  | | From | Donglin Peng <> | | Subject | [RFC bpf-next v8 0/9] Improve the performance of BTF type lookups with binary search | | Date | Wed, 26 Nov 2025 16:50:16 +0800 |
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From: pengdonglin <pengdonglin@xiaomi.com>
This patch series introduces significant performance improvements (~2855x) for BTF type lookups by implementing type permutation and binary search optimizations.
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-#9 optimize type lookup performance of two kernel functions.
Here is a simple performance result [1] to find 60,995 named types in vmlinux BTF: ./vmtest.sh -- ./test_progs -t btf_permute/perf -v
Results: | Condition | Lookup Time | Improvement | |--------------------|-------------|--------------| | Unsorted (Linear) | 27,697.4 ms | Baseline | | Sorted (Binary) | 9.7 ms | 2855x faster |
The binary search implementation reduces lookup time from 27.7 seconds to 9.7 milliseconds, achieving a **2855x** speedup for large-scale type queries.
Changelog: v8: - 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/
pengdonglin (9): 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: Optimize the performance of find_btf_percpu_datasec bpf: Optimize the performance of find_bpffs_btf_enums
include/linux/btf.h | 1 + kernel/bpf/btf.c | 148 +++++++++- kernel/bpf/inode.c | 42 ++- kernel/bpf/verifier.c | 7 +- tools/bpf/resolve_btfids/main.c | 68 +++++ tools/lib/bpf/btf.c | 260 ++++++++++++++++-- tools/lib/bpf/btf.h | 36 +++ tools/lib/bpf/libbpf.map | 1 + .../selftests/bpf/prog_tests/btf_permute.c | 228 +++++++++++++++ 9 files changed, 733 insertions(+), 58 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/btf_permute.c
-- 2.34.1
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