linux-kernel - [PATCH bpf-next] bpf: make kprobe_multi_link_prog_run always

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Message-ID: <20251126085246.309942-1-dongml2@chinatelecom.cn>
Date: Wed, 26 Nov 2025 16:52:46 +0800
From: Menglong Dong <menglong8.dong@...il.com>
To: ast@...nel.or,
	jolsa@...nel.org
Cc: kpsingh@...nel.org,
	mattbobrowski@...gle.com,
	song@...nel.org,
	ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org,
	martin.lau@...ux.dev,
	eddyz87@...il.com,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	sdf@...ichev.me,
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	rostedt@...dmis.org,
	mhiramat@...nel.org,
	mathieu.desnoyers@...icios.com,
	jiang.biao@...ux.dev,
	bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Subject: [PATCH bpf-next] bpf: make kprobe_multi_link_prog_run always_inline

Make kprobe_multi_link_prog_run() always inline to obtain better
performance. Before this patch, the bench performance is:

./bench trig-kprobe-multi
Setting up benchmark 'trig-kprobe-multi'...
Benchmark 'trig-kprobe-multi' started.
Iter   0 ( 95.485us): hits   62.462M/s ( 62.462M/prod), [...]
Iter   1 (-80.054us): hits   62.486M/s ( 62.486M/prod), [...]
Iter   2 ( 13.572us): hits   62.287M/s ( 62.287M/prod), [...]
Iter   3 ( 76.961us): hits   62.293M/s ( 62.293M/prod), [...]
Iter   4 (-77.698us): hits   62.394M/s ( 62.394M/prod), [...]
Iter   5 (-13.399us): hits   62.319M/s ( 62.319M/prod), [...]
Iter   6 ( 77.573us): hits   62.250M/s ( 62.250M/prod), [...]
Summary: hits   62.338 ± 0.083M/s ( 62.338M/prod)

And after this patch, the performance is:

Iter   0 (454.148us): hits   66.900M/s ( 66.900M/prod), [...]
Iter   1 (-435.540us): hits   68.925M/s ( 68.925M/prod), [...]
Iter   2 (  8.223us): hits   68.795M/s ( 68.795M/prod), [...]
Iter   3 (-12.347us): hits   68.880M/s ( 68.880M/prod), [...]
Iter   4 (  2.291us): hits   68.767M/s ( 68.767M/prod), [...]
Iter   5 ( -1.446us): hits   68.756M/s ( 68.756M/prod), [...]
Iter   6 ( 13.882us): hits   68.657M/s ( 68.657M/prod), [...]
Summary: hits   68.792 ± 0.087M/s ( 68.792M/prod)

As we can see, the performance of kprobe-multi increase from 62M/s to
68M/s.

Signed-off-by: Menglong Dong <dongml2@...natelecom.cn>
---
 kernel/trace/bpf_trace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index a795f7afbf3d..d57727abaade 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2529,7 +2529,7 @@ static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx)
 	return run_ctx->entry_ip;
 }
 
-static int
+static __always_inline int
 kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
 			   unsigned long entry_ip, struct ftrace_regs *fregs,
 			   bool is_return, void *data)
-- 
2.52.0