* [PATCH v1] perf stat bperf cgroup: Increase MAX_EVENTS from 32 to 1024
@ 2025-10-16 15:07 Ian Rogers
2025-10-20 2:12 ` Namhyung Kim
0 siblings, 1 reply; 2+ messages in thread
From: Ian Rogers @ 2025-10-16 15:07 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Namhyung Kim, Alexander Shishkin, Jiri Olsa, Ian Rogers,
Adrian Hunter, linux-perf-users, linux-kernel, bpf
The MAX_EVENTS value ensured a counted loop presumably to satisfy the
BPF verifier. It is possible to go past 32 events when gathering
uncore events. Increase the amount to 1024 as that should provide some
amount of headroom.
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/bpf_skel/bperf_cgroup.bpf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c b/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c
index 57cab7647a9a..18ab4d9b49ff 100644
--- a/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c
+++ b/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c
@@ -7,7 +7,7 @@
#include <bpf/bpf_core_read.h>
#define MAX_LEVELS 10 // max cgroup hierarchy level: arbitrary
-#define MAX_EVENTS 32 // max events per cgroup: arbitrary
+#define MAX_EVENTS 1024 // max events per cgroup: arbitrary
// NOTE: many of map and global data will be modified before loading
// from the userspace (perf tool) using the skeleton helpers.
--
2.51.0.788.g6d19910ace-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v1] perf stat bperf cgroup: Increase MAX_EVENTS from 32 to 1024
2025-10-16 15:07 [PATCH v1] perf stat bperf cgroup: Increase MAX_EVENTS from 32 to 1024 Ian Rogers
@ 2025-10-20 2:12 ` Namhyung Kim
0 siblings, 0 replies; 2+ messages in thread
From: Namhyung Kim @ 2025-10-20 2:12 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Alexander Shishkin, Jiri Olsa, Adrian Hunter, linux-perf-users,
linux-kernel, bpf, Ian Rogers
On Thu, 16 Oct 2025 08:07:18 -0700, Ian Rogers wrote:
> The MAX_EVENTS value ensured a counted loop presumably to satisfy the
> BPF verifier. It is possible to go past 32 events when gathering
> uncore events. Increase the amount to 1024 as that should provide some
> amount of headroom.
>
>
Applied to perf-tools-next, thanks!
Best regards,
Namhyung
^ permalink raw reply [flat|nested] 2+ messages in thread
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