linux-kernel - Re: [PATCH bpf-next v2 3/3] selftests/bpf: add benchmark testing for kprobe-multi-all

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Message-ID: <3664215.iIbC2pHGDl@7940hx>
Date: Fri, 29 Aug 2025 15:01:41 +0800
From: Menglong Dong <menglong.dong@...ux.dev>
To: Menglong Dong <menglong8.dong@...il.com>, Jiri Olsa <olsajiri@...il.com>
Cc: andrii@...nel.org, eddyz87@...il.com, mykolal@...com, ast@...nel.org,
 daniel@...earbox.net, martin.lau@...ux.dev, song@...nel.org,
 yonghong.song@...ux.dev, john.fastabend@...il.com, kpsingh@...nel.org,
 sdf@...ichev.me, haoluo@...gle.com, shuah@...nel.org, yikai.lin@...o.com,
 memxor@...il.com, bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject:
 Re: [PATCH bpf-next v2 3/3] selftests/bpf: add benchmark testing for
 kprobe-multi-all

On 2025/8/27 02:48 Jiri Olsa <olsajiri@...il.com> write:
> On Tue, Aug 26, 2025 at 04:04:30PM +0800, Menglong Dong wrote:
> > For now, the benchmark for kprobe-multi is single, which means there is
> > only 1 function is hooked during testing. Add the testing
> > "kprobe-multi-all", which will hook all the kernel functions during
> > the benchmark. And the "kretprobe-multi-all" is added too.
> 
> hi,
> fyi this bench causes panic on my setup.. very silent, so not sure
> yet which function we should blacklist next, attaching my .config

According to my testing, the panic is due to the task hang.
With so many debug config enabled(KASAN, LOCKDEP, etc),
the system will become quite slow. What's wrose, there are
many debug function is called during fprobe_entry(), which
makes the BPF much slower. If you wait long enough, the
testing can still run.

Add more symbol to the blacklist can mitigate this problem,
but we need to maintain many symbols for this purpose. So
I suggest that we only run this testing in product kernel.

What do you think?

Thanks!
Menglong Dong

> 
> jirka
>