Currently, we are only using the linear search method to find the type id by the name, which has a time complexity of O(n). This change involves sorting the names of btf types in ascending order and using binary search, which has a time complexity of O(log(n)). This idea was inspired by the following patch:
60443c88f3a8 ("kallsyms: Improve the performance of kallsyms_lookup_name()").
At present, this improvement is only for searching in vmlinux's and module's BTFs.
Another change is the search direction, where we search the BTF first and then its base, the type id of the first matched btf_type will be returned.
Here is a time-consuming result that finding 87590 type ids by their names in vmlinux's BTF.
Before: 158426 ms After: 114 ms
The average lookup performance has improved more than 1000x in the above scenario.
v4: - Divide the patch into two parts: kernel and libbpf - Use Eduard's code to sort btf_types in the btf__dedup function - Correct some btf testcases due to modifications of the order of btf_types.
v3: - Link: https://lore.kernel.org/all/20240608140835.965949-1-dolinux.peng@gmail.com/ - Sort btf_types during build process other than during boot, to reduce the overhead of memory and boot time.
v2: - Link: https://lore.kernel.org/all/20230909091646.420163-1-pengdonglin@sangfor.com....
Donglin Peng (3): libbpf: Sort btf_types in ascending order by name bpf: Using binary search to improve the performance of btf_find_by_name_kind libbpf: Using binary search to improve the performance of btf__find_by_name_kind
include/linux/btf.h | 1 + kernel/bpf/btf.c | 157 +++++++++- tools/lib/bpf/btf.c | 274 +++++++++++++--- tools/testing/selftests/bpf/prog_tests/btf.c | 296 +++++++++--------- .../bpf/prog_tests/btf_dedup_split.c | 64 ++-- 5 files changed, 555 insertions(+), 237 deletions(-)