linux-kernel - [PATCH bpf-next v2 4/4] selftests/bpf: do not hardcode target rate in test_tc

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Message-Id: <20251128-tc_edt-v2-4-26db48373e73@bootlin.com>
Date: Fri, 28 Nov 2025 23:27:21 +0100
From: Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
To: Alexei Starovoitov <ast@...nel.org>, 
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, 
 Martin KaFai Lau <martin.lau@...ux.dev>, 
 Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
 Yonghong Song <yonghong.song@...ux.dev>, 
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, 
 Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
 Jiri Olsa <jolsa@...nel.org>, Shuah Khan <shuah@...nel.org>
Cc: ebpf@...uxfoundation.org, 
 Bastien Curutchet <bastien.curutchet@...tlin.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, bpf@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
Subject: [PATCH bpf-next v2 4/4] selftests/bpf: do not hardcode target rate
 in test_tc_edt BPF program

test_tc_edt currently defines the target rate in both the userspace and
BPF parts. This value could be defined once in the userspace part if we
make it able to configure the BPF program before starting the test.

Add a target_rate variable in the BPF part, and make the userspace part
set it to the desired rate before attaching the shaping program.

Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
---
 tools/testing/selftests/bpf/prog_tests/test_tc_edt.c | 1 +
 tools/testing/selftests/bpf/progs/test_tc_edt.c      | 6 +++---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/test_tc_edt.c b/tools/testing/selftests/bpf/prog_tests/test_tc_edt.c
index 9ba69398eec4..462512fb191f 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_tc_edt.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_tc_edt.c
@@ -66,6 +66,7 @@ static int setup(struct test_tc_edt *skel)
 	ret = tc_prog_attach("veth2", -1, bpf_program__fd(skel->progs.tc_prog));
 	if (!ASSERT_OK(ret, "attach bpf prog"))
 		goto fail_close_server_ns;
+	skel->bss->target_rate = TARGET_RATE_MBPS * 1000 * 1000;
 	close_netns(nstoken_server);
 	close_netns(nstoken_client);
 
diff --git a/tools/testing/selftests/bpf/progs/test_tc_edt.c b/tools/testing/selftests/bpf/progs/test_tc_edt.c
index d31058cf4eca..4f6f03122d61 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_edt.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_edt.c
@@ -14,7 +14,6 @@
 #define TIME_HORIZON_NS (2000 * 1000 * 1000)
 #define NS_PER_SEC 1000000000
 #define ECN_HORIZON_NS 5000000
-#define THROTTLE_RATE_BPS (5 * 1000 * 1000)
 
 /* flow_key => last_tstamp timestamp used */
 struct {
@@ -24,12 +23,13 @@ struct {
 	__uint(max_entries, 1);
 } flow_map SEC(".maps");
 
+__uint64_t target_rate;
+
 static inline int throttle_flow(struct __sk_buff *skb)
 {
 	int key = 0;
 	uint64_t *last_tstamp = bpf_map_lookup_elem(&flow_map, &key);
-	uint64_t delay_ns = ((uint64_t)skb->len) * NS_PER_SEC /
-			THROTTLE_RATE_BPS;
+	uint64_t delay_ns = ((uint64_t)skb->len) * NS_PER_SEC / target_rate;
 	uint64_t now = bpf_ktime_get_ns();
 	uint64_t tstamp, next_tstamp = 0;
 

-- 
2.51.2