perf annotation: Switch lock from a mutex to a sharded_mutex

Remove the "struct mutex lock" variable from annotation that is
allocated per symbol. This removes in the region of 40 bytes per
symbol allocation. Use a sharded mutex where the number of shards is
set to the number of CPUs. Assuming good hashing of the annotation
(done based on the pointer), this means in order to contend there
needs to be more threads than CPUs, which is not currently true in any
perf command. Were contention an issue it is straightforward to
increase the number of shards in the mutex.

On my Debian/glibc based machine, this reduces the size of struct
annotation from 136 bytes to 96 bytes, or nearly 30%.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Yuan Can <yuancan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Link: https://lore.kernel.org/r/20230615040715.2064350-2-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

1 files changed, 8 insertions, 3 deletions

diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h
index 1c6335b8333a..962780559176 100644
--- a/tools/perf/util/annotate.h
+++ b/tools/perf/util/annotate.h
@@ -271,8 +271,7 @@ struct annotated_source {
 	struct sym_hist	   *histograms;
 };
 
-struct annotation {
-	struct mutex lock;
+struct LOCKABLE annotation {
 	u64			max_coverage;
 	u64			start;
 	u64			hit_cycles;
@@ -298,9 +297,15 @@ struct annotation {
 	struct annotated_source *src;
 };
 
-void annotation__init(struct annotation *notes);
+static inline void annotation__init(struct annotation *notes __maybe_unused)
+{
+}
 void annotation__exit(struct annotation *notes);
 
+void annotation__lock(struct annotation *notes) EXCLUSIVE_LOCK_FUNCTION(*notes);
+void annotation__unlock(struct annotation *notes) UNLOCK_FUNCTION(*notes);
+bool annotation__trylock(struct annotation *notes) EXCLUSIVE_TRYLOCK_FUNCTION(true, *notes);
+
 static inline int annotation__cycles_width(struct annotation *notes)
 {
 	if (notes->have_cycles && notes->options->show_minmax_cycle)