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 <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Yuan Can <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>

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)