From: Kyle Meyer <kyle.meyer@xxxxxxx> [ Upstream commit 9f94c7f947e919c343b30f080285af53d0fa9902 ] 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 ... Signed-off-by: Kyle Meyer <kyle.meyer@xxxxxxx> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Namhyung Kim <namhyung@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20190620193630.154025-1-meyerk@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- tools/perf/perf.h | 2 +- tools/perf/util/header.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/perf/perf.h b/tools/perf/perf.h index 21bf7f5a3cf5..19d435a9623b 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 b9a82598e2ac..7f2e3b1c746c 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -1173,7 +1173,7 @@ 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) -- 2.20.1
