From: Song Liu <song@kernel.org>
To: <bpf@vger.kernel.org>
Cc: <ast@kernel.org>, <daniel@iogearbox.net>, <andrii@kernel.org>,
<kernel-team@meta.com>, Song Liu <song@kernel.org>
Subject: [PATCH bpf-next] selftests/bpf: Use PERF_COUNT_HW_CPU_CYCLES event for get_branch_snapshot
Date: Fri, 7 Apr 2023 12:01:30 -0700 [thread overview]
Message-ID: <20230407190130.2093736-1-song@kernel.org> (raw)
perf_event with type=PERF_TYPE_RAW and config=0x1b00 turned out to be not
reliable in ensuring LBR is active. Thus, test_progs:get_branch_snapshot is
not reliable in some systems. Replace it with PERF_COUNT_HW_CPU_CYCLES
event, which gives more consistent results.
Signed-off-by: Song Liu <song@kernel.org>
---
tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c
index 3948da12a528..0394a1156d99 100644
--- a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c
+++ b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c
@@ -37,8 +37,8 @@ static int create_perf_events(void)
/* create perf event */
attr.size = sizeof(attr);
- attr.type = PERF_TYPE_RAW;
- attr.config = 0x1b00;
+ attr.type = PERF_TYPE_HARDWARE;
+ attr.config = PERF_COUNT_HW_CPU_CYCLES;
attr.sample_type = PERF_SAMPLE_BRANCH_STACK;
attr.branch_sample_type = PERF_SAMPLE_BRANCH_KERNEL |
PERF_SAMPLE_BRANCH_USER | PERF_SAMPLE_BRANCH_ANY;
--
2.34.1
next reply other threads:[~2023-04-07 19:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-07 19:01 Song Liu [this message]
2023-04-07 20:31 ` [PATCH bpf-next] selftests/bpf: Use PERF_COUNT_HW_CPU_CYCLES event for get_branch_snapshot Jiri Olsa
2023-04-07 22:30 ` patchwork-bot+netdevbpf
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