* [PATCH bpf-next] selftests/bpf: Use PERF_COUNT_HW_CPU_CYCLES event for get_branch_snapshot
@ 2023-04-07 19:01 Song Liu
2023-04-07 20:31 ` Jiri Olsa
2023-04-07 22:30 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Song Liu @ 2023-04-07 19:01 UTC (permalink / raw)
To: bpf; +Cc: ast, daniel, andrii, kernel-team, Song Liu
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: Use PERF_COUNT_HW_CPU_CYCLES event for get_branch_snapshot
2023-04-07 19:01 [PATCH bpf-next] selftests/bpf: Use PERF_COUNT_HW_CPU_CYCLES event for get_branch_snapshot Song Liu
@ 2023-04-07 20:31 ` Jiri Olsa
2023-04-07 22:30 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Jiri Olsa @ 2023-04-07 20:31 UTC (permalink / raw)
To: Song Liu; +Cc: bpf, ast, daniel, andrii, kernel-team
On Fri, Apr 07, 2023 at 12:01:30PM -0700, Song Liu wrote:
> 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>
Acked-by: Jiri Olsa <jolsa@kernel.org>
jirka
> ---
> 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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: Use PERF_COUNT_HW_CPU_CYCLES event for get_branch_snapshot
2023-04-07 19:01 [PATCH bpf-next] selftests/bpf: Use PERF_COUNT_HW_CPU_CYCLES event for get_branch_snapshot Song Liu
2023-04-07 20:31 ` Jiri Olsa
@ 2023-04-07 22:30 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2023-04-07 22:30 UTC (permalink / raw)
To: Song Liu; +Cc: bpf, ast, daniel, andrii, kernel-team
Hello:
This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:
On Fri, 7 Apr 2023 12:01:30 -0700 you wrote:
> 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>
>
> [...]
Here is the summary with links:
- [bpf-next] selftests/bpf: Use PERF_COUNT_HW_CPU_CYCLES event for get_branch_snapshot
https://git.kernel.org/bpf/bpf-next/c/3ebf5212bf04
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-04-07 19:01 [PATCH bpf-next] selftests/bpf: Use PERF_COUNT_HW_CPU_CYCLES event for get_branch_snapshot Song Liu
2023-04-07 20:31 ` Jiri Olsa
2023-04-07 22:30 ` patchwork-bot+netdevbpf
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