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* [PATCH v1] Increase MAX_NR_CPUS and MAX_CACHES
@ 2019-06-20 19:36 Kyle Meyer
  2019-06-24 18:50 ` Arnaldo Carvalho de Melo
  2019-07-03 14:03 ` [tip:perf/core] perf tools: " tip-bot for Kyle Meyer
  0 siblings, 2 replies; 4+ messages in thread
From: Kyle Meyer @ 2019-06-20 19:36 UTC (permalink / raw)
  Cc: Kyle Meyer, Peter Zijlstra, Ingo Molnar,
	Arnaldo Carvalho de Melo, Alexander Shishkin, Jiri Olsa,
	Namhyung Kim, linux-kernel

From: Kyle Meyer <kyle.meyer@hpe.com>

Attempting to profile 1024 or more CPUs with perf causes two errors:

perf record -a
[ perf record: Woken up X times to write data ]
way too many cpu caches..
[ perf record: Captured and wrote X MB perf.data (X samples) ]

perf report -C 1024
Error: failed to set  cpu bitmap
Requested CPU 1024 too large. Consider raising MAX_NR_CPUS

Increasing MAX_NR_CPUS from 1024 to 2048 and redefining MAX_CACHES as
MAX_NR_CPUS * 4 returns normal functionality to perf:

perf record -a
[ perf record: Woken up X times to write data ]
[ perf record: Captured and wrote X MB perf.data (X samples) ]

perf report -C 1024
...

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com>
---
 samples/bpf/map_perf_test_kern.c | 2 +-
 samples/bpf/map_perf_test_user.c | 2 +-
 tools/perf/perf.h                | 2 +-
 tools/perf/util/header.c         | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/samples/bpf/map_perf_test_kern.c b/samples/bpf/map_perf_test_kern.c
index 2b2ffb97018b..342738a1e386 100644
--- a/samples/bpf/map_perf_test_kern.c
+++ b/samples/bpf/map_perf_test_kern.c
@@ -11,7 +11,7 @@
 #include "bpf_helpers.h"
 
 #define MAX_ENTRIES 1000
-#define MAX_NR_CPUS 1024
+#define MAX_NR_CPUS 2048
 
 struct bpf_map_def SEC("maps") hash_map = {
 	.type = BPF_MAP_TYPE_HASH,
diff --git a/samples/bpf/map_perf_test_user.c b/samples/bpf/map_perf_test_user.c
index fe5564bff39b..da3c101ca776 100644
--- a/samples/bpf/map_perf_test_user.c
+++ b/samples/bpf/map_perf_test_user.c
@@ -22,7 +22,7 @@
 #include "bpf_load.h"
 
 #define TEST_BIT(t) (1U << (t))
-#define MAX_NR_CPUS 1024
+#define MAX_NR_CPUS 2048
 
 static __u64 time_get_ns(void)
 {
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index 711e009381ec..74d0124d38f3 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -26,7 +26,7 @@ static inline unsigned long long rdclock(void)
 }
 
 #ifndef MAX_NR_CPUS
-#define MAX_NR_CPUS			1024
+#define MAX_NR_CPUS			2048
 #endif
 
 extern const char *input_name;
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 06ddb6618ef3..abc9c2145efe 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1121,7 +1121,7 @@ static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp)
 	return 0;
 }
 
-#define MAX_CACHES 2000
+#define MAX_CACHES (MAX_NR_CPUS * 4)
 
 static int write_cache(struct feat_fd *ff,
 		       struct perf_evlist *evlist __maybe_unused)
-- 
2.12.3


^ permalink raw reply related	[flat|nested] 4+ messages in thread

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2019-06-20 19:36 [PATCH v1] Increase MAX_NR_CPUS and MAX_CACHES Kyle Meyer
2019-06-24 18:50 ` Arnaldo Carvalho de Melo
2019-06-24 19:04   ` Jiri Olsa
2019-07-03 14:03 ` [tip:perf/core] perf tools: " tip-bot for Kyle Meyer

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