Re: [PATCH bpf-next v2 2/2] [no_merge] selftests/bpf: Benchmark runtime performance with private stack

[Yonghong Song <yonghong.song@linux.dev>]

On 7/18/24 5:36 PM, Alexei Starovoitov wrote:
> On Thu, Jul 18, 2024 at 2:44 PM Yonghong Song <yonghong.song@linux.dev> wrote:
>>
>>>     $ perf record -- ./bench -w3 -d10 -a --nr-batch-iters=4096 private-stack
>>>       18.94%  bench                                              [k]
>>>       16.88%  bench    bpf_prog_bcf7977d3b93787c_func1           [k] bpf_prog_bcf7977d3b93787c_func1
>>>       15.77%  bench    bpf_trampoline_6442522961                 [k]
> ...
>
>>> NOTE: I tried 6.4 perf and 6.10 perf, both of which have issues. I will investigate this further.
>> I tried with perf built with latest bpf-next and with no-private-stack, the issue still
>> exists. Will debug more.
> Try this fix:
> https://lore.kernel.org/all/20240714065533.1112616-1-houtao@huaweicloud.com/

It does fix the problem. The 'perf report' for private-stack flavor:

   18.94%  bench    bpf_prog_71f1b7d5309b304a_bench_trigger_fentry_batch  [k] bpf_prog_71f1b7d5309b304a_bench_trigger_fentry_batch
   16.50%  bench    bpf_prog_bcf7977d3b93787c_func1                       [k] bpf_prog_bcf7977d3b93787c_func1
   15.75%  bench    bpf_trampoline_6442522961                             [k] bpf_trampoline_6442522961
   11.72%  bench    [kernel.vmlinux]                                      [k] migrate_enable
   11.63%  bench    [kernel.vmlinux]                                      [k] __bpf_prog_enter_recur
   11.37%  bench    [kernel.vmlinux]                                      [k] __bpf_prog_exit_recur
    6.17%  bench    [kernel.vmlinux]                                      [k] migrate_disable
    3.59%  bench    bpf_prog_d9703036495d54b0_trigger_driver              [k] bpf_prog_d9703036495d54b0_trigger_driver
    3.51%  bench    [kernel.vmlinux]                                      [k] bpf_get_numa_node_id
    0.05%  bench    bench                                                 [.] bpf_prog_test_run_opts

>
> btw you were cc-ed on it. your @ fb goes to spam ? ;)

It is in my inbox. Sadly I skipped it since it is for perf system and I focused on
several of my patches in the last few days.