On 7/15/25 16:36, Menglong Dong wrote:
On 7/15/25 10:25, Alexei Starovoitov wrote:
Pls share top 10 from "perf report" while running the bench.
I'm curious about what's hot.
Last time I benchmarked fentry/fexit migrate_disable/enable were
one the hottest functions. I suspect it's the case here as well.
You are right, the migrate_disable/enable are the hottest functions in
both bpf trampoline and global trampoline. Following is the perf top
for fentry-multi:
36.36% bpf_prog_2dcccf652aac1793_bench_trigger_fentry_multi [k]
bpf_prog_2dcccf652aac1793_bench_trigger_fentry_multi 20.54% [kernel]
[k] migrate_enable 19.35% [kernel] [k] bpf_global_caller_5_run 6.52%
[kernel] [k] bpf_global_caller_5 3.58% libc.so.6 [.] syscall 2.88%
[kernel] [k] entry_SYSCALL_64 1.50% [kernel] [k] memchr_inv 1.39%
[kernel] [k] fput 1.04% [kernel] [k] migrate_disable 0.91% [kernel]
[k] _copy_to_user
And I also did the testing for fentry:
54.63% bpf_prog_2dcccf652aac1793_bench_trigger_fentry [k]
bpf_prog_2dcccf652aac1793_bench_trigger_fentry
10.43% [kernel] [k] migrate_enable
10.07% bpf_trampoline_6442517037 [k] bpf_trampoline_6442517037
8.06% [kernel] [k] __bpf_prog_exit_recur 4.11% libc.so.6 [.] syscall
2.15% [kernel] [k] entry_SYSCALL_64 1.48% [kernel] [k] memchr_inv
1.32% [kernel] [k] fput 1.16% [kernel] [k] _copy_to_user 0.73%
[kernel] [k] bpf_prog_test_run_raw_tp
The migrate_enable/disable are used to do the recursive checking,
and I even wanted to perform recursive checks in the same way as
ftrace to eliminate this overhead :/
Sorry that I'm not familiar with Thunderbird yet, and the perf top
messed up. Following are the test results for fentry-multi:
36.36% bpf_prog_2dcccf652aac1793_bench_trigger_fentry_multi [k]
bpf_prog_2dcccf652aac1793_bench_trigger_fentry_multi
20.54% [kernel] [k] migrate_enable
19.35% [kernel] [k] bpf_global_caller_5_run
6.52% [kernel] [k] bpf_global_caller_5
3.58% libc.so.6 [.] syscall
2.88% [kernel] [k] entry_SYSCALL_64
1.50% [kernel] [k] memchr_inv
1.39% [kernel] [k] fput
1.04% [kernel] [k] migrate_disable
0.91% [kernel] [k] _copy_to_user
And I also did the testing for fentry:
54.63% bpf_prog_2dcccf652aac1793_bench_trigger_fentry [k]
bpf_prog_2dcccf652aac1793_bench_trigger_fentry
10.43% [kernel] [k] migrate_enable
10.07% bpf_trampoline_6442517037 [k] bpf_trampoline_6442517037
8.06% [kernel] [k] __bpf_prog_exit_recur
4.11% libc.so.6 [.] syscall
2.15% [kernel] [k] entry_SYSCALL_64
1.48% [kernel] [k] memchr_inv
1.32% [kernel] [k] fput
1.16% [kernel] [k] _copy_to_user
0.73% [kernel] [k] bpf_prog_test_run_raw_tp
The migrate_enable/disable are used to do the recursive checking,
and I even wanted to perform recursive checks in the same way as
ftrace to eliminate this overhead :/
Thanks!
Menglong Dong
