perf header: Support HYBRID_TOPOLOGY feature

It is useful to let the user know about the hybrid topology.

Add the HYBRID_TOPOLOGY feature in header to indicate the core CPUs
and the atom CPUs.

With this patch a perf.data generated on a hybrid platform reports
the hybrid CPU list:

  root@otcpl-adl-s-2:~# perf report --header-only -I
  ...
  # hybrid cpu system:
  # cpu_core cpu list : 0-15
  # cpu_atom cpu list : 16-23

For a perf.data generated on a non-hybrid platform, reports a message
that HYBRID_TOPOLOGY is missing:

  root@kbl-ppc:~# perf report --header-only -I
  ...
  # missing features: TRACING_DATA BRANCH_STACK GROUP_DESC AUXTRACE STAT CLOCKID DIR_FORMAT COMPRESSED CLOCK_DATA HYBRID_TOPOLOGY

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210514122948.9472-2-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt
index 9ee96640744e..fbee9e580ee4 100644
--- a/tools/perf/Documentation/perf.data-file-format.txt
+++ b/tools/perf/Documentation/perf.data-file-format.txt
@@ -402,6 +402,23 @@ struct {
 	u64 clockid_time_ns;
 };
 
+	HEADER_HYBRID_TOPOLOGY = 30,
+
+Indicate the hybrid CPUs. The format of data is as below.
+
+struct {
+	u32 nr;
+	struct {
+		char pmu_name[];
+		char cpus[];
+	} [nr]; /* Variable length records */
+};
+
+Example:
+  hybrid cpu system:
+  cpu_core cpu list : 0-15
+  cpu_atom cpu list : 16-23
+
 	other bits are reserved and should ignored for now
 	HEADER_FEAT_BITS	= 256,