[RFC PATCH v1 03/37] perf evlist: replace evsel__cpu_iter* functions with evsel__find_cpu

[Riccardo Mancini]

Commit a8cbe40fe9f4ba49 ("perf evsel: Add iterator to iterate over events
ordered by CPU") introduced an iterator for evsel.core.cpus inside evsel
which is used to iterate over evlist one CPU at a time.

However, this solution is hacky since it involves a mutable state in the
evsel which is supposed to be unmodified during iteration.
Sice checking that a CPU is within the evsel can be done quickly in
O(logn) time, this patch replaces the aforementioned iterator with a
simple check.

Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Riccardo Mancini <rickyman7@xxxxxxxxx>
---
 tools/perf/builtin-stat.c | 24 +++++++++--------
 tools/perf/util/evlist.c  | 54 +++++++++++----------------------------
 tools/perf/util/evlist.h  |  5 +---
 tools/perf/util/evsel.h   |  1 -
 4 files changed, 30 insertions(+), 54 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 84de61795e67bbb9..62dcc001c8f0a78b 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -407,7 +407,7 @@ static int read_affinity_counters(struct timespec *rs)
 {
 	struct evsel *counter;
 	struct affinity affinity;
-	int i, ncpus, cpu;
+	int i, ncpus, cpu, cpu_idx;
 
 	if (all_counters_use_bpf)
 		return 0;
@@ -424,13 +424,14 @@ static int read_affinity_counters(struct timespec *rs)
 		affinity__set(&affinity, cpu);
 
 		evlist__for_each_entry(evsel_list, counter) {
-			if (evsel__cpu_iter_skip(counter, cpu))
+			cpu_idx = evsel__find_cpu(counter, cpu);
+			if (cpu_idx < 0)
 				continue;
 			if (evsel__is_bpf(counter))
 				continue;
 			if (!counter->err) {
 				counter->err = read_counter_cpu(counter, rs,
-								counter->cpu_iter - 1);
+								cpu_idx);
 			}
 		}
 	}
@@ -789,7 +790,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 	const bool forks = (argc > 0);
 	bool is_pipe = STAT_RECORD ? perf_stat.data.is_pipe : false;
 	struct affinity affinity;
-	int i, cpu, err;
+	int i, cpu, cpu_idx, err;
 	bool second_pass = false;
 
 	if (forks) {
@@ -823,7 +824,8 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 		affinity__set(&affinity, cpu);
 
 		evlist__for_each_entry(evsel_list, counter) {
-			if (evsel__cpu_iter_skip(counter, cpu))
+			cpu_idx = evsel__find_cpu(counter, cpu);
+			if (cpu_idx < 0)
 				continue;
 			if (counter->reset_group || counter->errored)
 				continue;
@@ -831,7 +833,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 				continue;
 try_again:
 			if (create_perf_stat_counter(counter, &stat_config, &target,
-						     counter->cpu_iter - 1) < 0) {
+						     cpu_idx) < 0) {
 
 				/*
 				 * Weak group failed. We cannot just undo this here
@@ -877,22 +879,24 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 			evlist__for_each_entry(evsel_list, counter) {
 				if (!counter->reset_group && !counter->errored)
 					continue;
-				if (evsel__cpu_iter_skip_no_inc(counter, cpu))
+				cpu_idx = evsel__find_cpu(counter, cpu);
+				if (cpu_idx < 0)
 					continue;
-				perf_evsel__close_cpu(&counter->core, counter->cpu_iter);
+				perf_evsel__close_cpu(&counter->core, cpu_idx);
 			}
 			/* Now reopen weak */
 			evlist__for_each_entry(evsel_list, counter) {
 				if (!counter->reset_group && !counter->errored)
 					continue;
-				if (evsel__cpu_iter_skip(counter, cpu))
+				cpu_idx = evsel__find_cpu(counter, cpu);
+				if (cpu_idx < 0)
 					continue;
 				if (!counter->reset_group)
 					continue;
 try_again_reset:
 				pr_debug2("reopening weak %s\n", evsel__name(counter));
 				if (create_perf_stat_counter(counter, &stat_config, &target,
-							     counter->cpu_iter - 1) < 0) {
+							     cpu_idx) < 0) {
 
 					switch (stat_handle_error(counter)) {
 					case COUNTER_FATAL:
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 47581a237c7a7848..3d55d9a53b9f4875 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -341,36 +341,9 @@ static int evlist__nr_threads(struct evlist *evlist, struct evsel *evsel)
 		return perf_thread_map__nr(evlist->core.threads);
 }
 
-void evlist__cpu_iter_start(struct evlist *evlist)
+int evsel__find_cpu(struct evsel *ev, int cpu)
 {
-	struct evsel *pos;
-
-	/*
-	 * Reset the per evsel cpu_iter. This is needed because
-	 * each evsel's cpumap may have a different index space,
-	 * and some operations need the index to modify
-	 * the FD xyarray (e.g. open, close)
-	 */
-	evlist__for_each_entry(evlist, pos)
-		pos->cpu_iter = 0;
-}
-
-bool evsel__cpu_iter_skip_no_inc(struct evsel *ev, int cpu)
-{
-	if (ev->cpu_iter >= ev->core.cpus->nr)
-		return true;
-	if (cpu >= 0 && ev->core.cpus->map[ev->cpu_iter] != cpu)
-		return true;
-	return false;
-}
-
-bool evsel__cpu_iter_skip(struct evsel *ev, int cpu)
-{
-	if (!evsel__cpu_iter_skip_no_inc(ev, cpu)) {
-		ev->cpu_iter++;
-		return false;
-	}
-	return true;
+	return perf_cpu_map__idx(ev->core.cpus, cpu);
 }
 
 static int evsel__strcmp(struct evsel *pos, char *evsel_name)
@@ -400,7 +373,7 @@ static void __evlist__disable(struct evlist *evlist, char *evsel_name)
 {
 	struct evsel *pos;
 	struct affinity affinity;
-	int cpu, i, imm = 0;
+	int cpu, i, imm = 0, cpu_idx;
 	bool has_imm = false;
 
 	if (affinity__setup(&affinity) < 0)
@@ -414,7 +387,8 @@ static void __evlist__disable(struct evlist *evlist, char *evsel_name)
 			evlist__for_each_entry(evlist, pos) {
 				if (evsel__strcmp(pos, evsel_name))
 					continue;
-				if (evsel__cpu_iter_skip(pos, cpu))
+				cpu_idx = evsel__find_cpu(pos, cpu);
+				if (cpu_idx < 0)
 					continue;
 				if (pos->disabled || !evsel__is_group_leader(pos) || !pos->core.fd)
 					continue;
@@ -422,7 +396,7 @@ static void __evlist__disable(struct evlist *evlist, char *evsel_name)
 					has_imm = true;
 				if (pos->immediate != imm)
 					continue;
-				evsel__disable_cpu(pos, pos->cpu_iter - 1);
+				evsel__disable_cpu(pos, cpu_idx);
 			}
 		}
 		if (!has_imm)
@@ -462,7 +436,7 @@ static void __evlist__enable(struct evlist *evlist, char *evsel_name)
 {
 	struct evsel *pos;
 	struct affinity affinity;
-	int cpu, i;
+	int cpu, i, cpu_idx;
 
 	if (affinity__setup(&affinity) < 0)
 		return;
@@ -473,11 +447,12 @@ static void __evlist__enable(struct evlist *evlist, char *evsel_name)
 		evlist__for_each_entry(evlist, pos) {
 			if (evsel__strcmp(pos, evsel_name))
 				continue;
-			if (evsel__cpu_iter_skip(pos, cpu))
+			cpu_idx = evsel__find_cpu(pos, cpu);
+			if (cpu_idx < 0)
 				continue;
 			if (!evsel__is_group_leader(pos) || !pos->core.fd)
 				continue;
-			evsel__enable_cpu(pos, pos->cpu_iter - 1);
+			evsel__enable_cpu(pos, cpu_idx);
 		}
 	}
 	affinity__cleanup(&affinity);
@@ -1264,7 +1239,7 @@ void evlist__close(struct evlist *evlist)
 {
 	struct evsel *evsel;
 	struct affinity affinity;
-	int cpu, i;
+	int cpu, i, cpu_idx;
 
 	/*
 	 * With perf record core.cpus is usually NULL.
@@ -1282,9 +1257,10 @@ void evlist__close(struct evlist *evlist)
 		affinity__set(&affinity, cpu);
 
 		evlist__for_each_entry_reverse(evlist, evsel) {
-			if (evsel__cpu_iter_skip(evsel, cpu))
-			    continue;
-			perf_evsel__close_cpu(&evsel->core, evsel->cpu_iter - 1);
+			cpu_idx = evsel__find_cpu(evsel, cpu);
+			if (cpu_idx < 0)
+				continue;
+			perf_evsel__close_cpu(&evsel->core, cpu_idx);
 		}
 	}
 	affinity__cleanup(&affinity);
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 5c22383489ae4905..fde893170c7ba6d2 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -310,15 +310,12 @@ void evlist__to_front(struct evlist *evlist, struct evsel *move_evsel);
 	__evlist__for_each_entry_safe(&(evlist)->core.entries, tmp, evsel)
 
 #define evlist__for_each_cpu(evlist, index, cpu)	\
-	evlist__cpu_iter_start(evlist);			\
 	perf_cpu_map__for_each_cpu (cpu, index, (evlist)->core.all_cpus)
 
 struct evsel *evlist__get_tracking_event(struct evlist *evlist);
 void evlist__set_tracking_event(struct evlist *evlist, struct evsel *tracking_evsel);
 
-void evlist__cpu_iter_start(struct evlist *evlist);
-bool evsel__cpu_iter_skip(struct evsel *ev, int cpu);
-bool evsel__cpu_iter_skip_no_inc(struct evsel *ev, int cpu);
+int evsel__find_cpu(struct evsel *ev, int cpu);
 
 struct evsel *evlist__find_evsel_by_str(struct evlist *evlist, const char *str);
 
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 80383096d51c5f00..eabccce406886320 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -119,7 +119,6 @@ struct evsel {
 	bool			errored;
 	struct hashmap		*per_pkg_mask;
 	int			err;
-	int			cpu_iter;
 	struct {
 		evsel__sb_cb_t	*cb;
 		void		*data;
-- 
2.31.1