perf annotate: Save branch counters for each block

When annotating a basic block, it's useful to display the occurrences
of other events in the block.

The branch counter feature is only available for newer Intel platforms.

So a dedicated option to display the branch counters is not introduced.

Reuse the existing --total-cycles option, which triggers the annotation
of a basic block and displays the cycle-related annotation.

When the branch counters information is available, the branch counters
are automatically appended after all the cycle-related annotation.

Accounting the branch counters as well when accounting the cycles in
hist__account_cycles().

In 'struct annotated_branch', introduce a br_cntr array to save the
accumulation of each branch counter.

In a sample, all the branch counters for a branch are saved in a u64
space.

Because the saturation of a branch counter is small, e.g., for Intel
Sierra Forest, the saturation is only 3.

Add ANNOTATION__BR_CNTR_SATURATED_FLAG to indicate if a branch counter
once saturated. That can be used to indicate a potential event lost
because of the saturation.

Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240813160208.2493643-5-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 706be5e4a076..c08774d06d14 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2141,6 +2141,7 @@ struct branch_info *sample__resolve_bstack(struct perf_sample *sample,
 	unsigned int i;
 	const struct branch_stack *bs = sample->branch_stack;
 	struct branch_entry *entries = perf_sample__branch_entries(sample);
+	u64 *branch_stack_cntr = sample->branch_stack_cntr;
 	struct branch_info *bi = calloc(bs->nr, sizeof(struct branch_info));
 
 	if (!bi)
@@ -2150,6 +2151,8 @@ struct branch_info *sample__resolve_bstack(struct perf_sample *sample,
 		ip__resolve_ams(al->thread, &bi[i].to, entries[i].to);
 		ip__resolve_ams(al->thread, &bi[i].from, entries[i].from);
 		bi[i].flags = entries[i].flags;
+		if (branch_stack_cntr)
+			bi[i].branch_stack_cntr  = branch_stack_cntr[i];
 	}
 	return bi;
 }