perf kvm: Use histograms list to replace cached list

perf kvm tool defines its own cached list which is managed with RB tree,
histograms also provide RB tree to manage data entries. Since now we
have introduced histograms in the tool, it's not necessary to use the
self defined list and we can directly use histograms list to manage
KVM events.

This patch changes to use histograms list to track KVM events, and it
invokes the common function hists__output_resort_cb() to sort result,
this also give us flexibility to extend more sorting key words easily.

After histograms list supported, the cached list is redundant so remove
the relevant code for it.

Committer notes:

kvm_hists__reinit() is only used by functions enclosed in:

#if defined(HAVE_KVM_STAT_SUPPORT) && defined(HAVE_LIBTRACEEVENT)

So do it with this new function as well.

Signed-off-by: Leo Yan <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: John Garry <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-kvm.c

···
 	perf_hpp_list__init(&kvm_hists.list);
 	return kvm_hpp_list__parse(&kvm_hists.list, NULL, "ev_name");
 }
+
+static int kvm_hists__reinit(const char *output, const char *sort)
+{
+	perf_hpp__reset_output_field(&kvm_hists.list);
+	return kvm_hpp_list__parse(&kvm_hists.list, output, sort);
+}
 #endif // defined(HAVE_KVM_STAT_SUPPORT) && defined(HAVE_LIBTRACEEVENT)
 
 static const char *get_filename_for_perf_kvm(void)
···
 	struct kvm_event *last_event;
 };
 
-
-static void init_kvm_event_record(struct perf_kvm_stat *kvm)
-{
-	unsigned int i;
-
-	for (i = 0; i < EVENTS_CACHE_SIZE; i++)
-		INIT_LIST_HEAD(&kvm->kvm_events_cache[i]);
-}
-
 #ifdef HAVE_TIMERFD_SUPPORT
-static void clear_events_cache_stats(struct list_head *kvm_events_cache)
+static void clear_events_cache_stats(void)
 {
-	struct list_head *head;
+	struct rb_root_cached *root;
+	struct rb_node *nd;
 	struct kvm_event *event;
-	unsigned int i;
-	int j;
+	int i;
 
-	for (i = 0; i < EVENTS_CACHE_SIZE; i++) {
-		head = &kvm_events_cache[i];
-		list_for_each_entry(event, head, hash_entry) {
-			/* reset stats for event */
-			event->total.time = 0;
-			init_stats(&event->total.stats);
+	if (hists__has(&kvm_hists.hists, need_collapse))
+		root = &kvm_hists.hists.entries_collapsed;
+	else
+		root = kvm_hists.hists.entries_in;
 
-			for (j = 0; j < event->max_vcpu; ++j) {
-				event->vcpu[j].time = 0;
-				init_stats(&event->vcpu[j].stats);
-			}
+	for (nd = rb_first_cached(root); nd; nd = rb_next(nd)) {
+		struct hist_entry *he;
+
+		he = rb_entry(nd, struct hist_entry, rb_node_in);
+		event = container_of(he, struct kvm_event, he);
+
+		/* reset stats for event */
+		event->total.time = 0;
+		init_stats(&event->total.stats);
+
+		for (i = 0; i < event->max_vcpu; ++i) {
+			event->vcpu[i].time = 0;
+			init_stats(&event->vcpu[i].stats);
 		}
 	}
 }
 #endif
-
-static int kvm_events_hash_fn(u64 key)
-{
-	return key & (EVENTS_CACHE_SIZE - 1);
-}
 
 static bool kvm_event_expand(struct kvm_event *event, int vcpu_id)
 {
···
 	return true;
 }
 
-static struct kvm_event *kvm_alloc_init_event(struct perf_kvm_stat *kvm,
-					      struct event_key *key,
-					      struct perf_sample *sample __maybe_unused)
+static void *kvm_he_zalloc(size_t size)
 {
-	struct kvm_event *event;
+	struct kvm_event *kvm_ev;
 
-	event = zalloc(sizeof(*event));
-	if (!event) {
-		pr_err("Not enough memory\n");
+	kvm_ev = zalloc(size + sizeof(*kvm_ev));
+	if (!kvm_ev)
 		return NULL;
-	}
 
-	event->perf_kvm = kvm;
-	event->key = *key;
-	init_stats(&event->total.stats);
-	return event;
+	init_stats(&kvm_ev->total.stats);
+	hists__inc_nr_samples(&kvm_hists.hists, 0);
+	return &kvm_ev->he;
 }
+
+static void kvm_he_free(void *he)
+{
+	struct kvm_event *kvm_ev;
+
+	free(((struct hist_entry *)he)->kvm_info);
+	kvm_ev = container_of(he, struct kvm_event, he);
+	free(kvm_ev);
+}
+
+static struct hist_entry_ops kvm_ev_entry_ops = {
+	.new	= kvm_he_zalloc,
+	.free	= kvm_he_free,
+};
 
 static struct kvm_event *find_create_kvm_event(struct perf_kvm_stat *kvm,
 					       struct event_key *key,
 					       struct perf_sample *sample)
 {
 	struct kvm_event *event;
-	struct list_head *head;
+	struct hist_entry *he;
+	struct kvm_info *ki;
 
 	BUG_ON(key->key == INVALID_KEY);
 
-	head = &kvm->kvm_events_cache[kvm_events_hash_fn(key->key)];
-	list_for_each_entry(event, head, hash_entry) {
-		if (event->key.key == key->key && event->key.info == key->info)
-			return event;
+	ki = zalloc(sizeof(*ki));
+	if (!ki) {
+		pr_err("Failed to allocate kvm info\n");
+		return NULL;
 	}
 
-	event = kvm_alloc_init_event(kvm, key, sample);
-	if (!event)
+	kvm->events_ops->decode_key(kvm, key, ki->name);
+	he = hists__add_entry_ops(&kvm_hists.hists, &kvm_ev_entry_ops,
+				  &kvm->al, NULL, NULL, NULL, ki, sample, true);
+	if (he == NULL) {
+		pr_err("Failed to allocate hist entry\n");
+		free(ki);
 		return NULL;
+	}
 
-	list_add(&event->hash_entry, head);
+	event = container_of(he, struct kvm_event, he);
+	if (!event->perf_kvm) {
+		event->perf_kvm = kvm;
+		event->key = *key;
+	}
+
 	return event;
 }
 
···
 	return false;
 }
 
-static void insert_to_result(struct rb_root *result, struct kvm_event *event,
-			     key_cmp_fun bigger, int vcpu)
-{
-	struct rb_node **rb = &result->rb_node;
-	struct rb_node *parent = NULL;
-	struct kvm_event *p;
-
-	while (*rb) {
-		p = container_of(*rb, struct kvm_event, rb);
-		parent = *rb;
-
-		if (bigger(event, p, vcpu) > 0)
-			rb = &(*rb)->rb_left;
-		else
-			rb = &(*rb)->rb_right;
-	}
-
-	rb_link_node(&event->rb, parent, rb);
-	rb_insert_color(&event->rb, result);
-}
-
 static bool event_is_valid(struct kvm_event *event, int vcpu)
 {
 	return !!get_event_count(event, vcpu);
 }
 
-static void sort_result(struct perf_kvm_stat *kvm)
+static int filter_cb(struct hist_entry *he, void *arg __maybe_unused)
 {
-	unsigned int i;
-	int vcpu = kvm->trace_vcpu;
 	struct kvm_event *event;
+	struct perf_kvm_stat *perf_kvm;
 
-	for (i = 0; i < EVENTS_CACHE_SIZE; i++) {
-		list_for_each_entry(event, &kvm->kvm_events_cache[i], hash_entry) {
-			if (event_is_valid(event, vcpu)) {
-				insert_to_result(&kvm->result, event,
-						 kvm->compare, vcpu);
-			}
-		}
-	}
+	event = container_of(he, struct kvm_event, he);
+	perf_kvm = event->perf_kvm;
+	if (!event_is_valid(event, perf_kvm->trace_vcpu))
+		he->filtered = 1;
+	else
+		he->filtered = 0;
+	return 0;
 }
 
-/* returns left most element of result, and erase it */
-static struct kvm_event *pop_from_result(struct rb_root *result)
+static void sort_result(struct perf_kvm_stat *kvm)
 {
-	struct rb_node *node = rb_first(result);
+	const char *output_columns = "ev_name,sample,time,max_t,min_t,mean_t";
 
-	if (!node)
-		return NULL;
-
-	rb_erase(node, result);
-	return container_of(node, struct kvm_event, rb);
+	kvm_hists__reinit(output_columns, kvm->sort_key);
+	hists__collapse_resort(&kvm_hists.hists, NULL);
+	hists__output_resort_cb(&kvm_hists.hists, NULL, filter_cb);
 }
 
 static void print_vcpu_info(struct perf_kvm_stat *kvm)
···
 	char decode[KVM_EVENT_NAME_LEN];
 	struct kvm_event *event;
 	int vcpu = kvm->trace_vcpu;
+	struct rb_node *nd;
 
 	if (kvm->live) {
 		puts(CONSOLE_CLEAR);
···
 	pr_info("%16s ", "Avg time");
 	pr_info("\n\n");
 
-	while ((event = pop_from_result(&kvm->result))) {
+	for (nd = rb_first_cached(&kvm_hists.hists.entries); nd; nd = rb_next(nd)) {
+		struct hist_entry *he;
 		u64 ecount, etime, max, min;
 
+		he = rb_entry(nd, struct hist_entry, rb_node);
+		if (he->filtered)
+			continue;
+
+		event = container_of(he, struct kvm_event, he);
 		ecount = get_event_count(event, vcpu);
 		etime = get_event_time(event, vcpu);
 		max = get_event_max(event, vcpu);
···
 	sort_result(kvm);
 	print_result(kvm);
 
+	/* Reset sort list to "ev_name" */
+	kvm_hists__reinit(NULL, "ev_name");
+
 	/* reset counts */
-	clear_events_cache_stats(kvm->kvm_events_cache);
+	clear_events_cache_stats();
 	kvm->total_count = 0;
 	kvm->total_time = 0;
 	kvm->lost_events = 0;
···
 	}
 
 	set_term_quiet_input(&save);
-	init_kvm_event_record(kvm);
 
 	kvm_hists__init();
 
···
 	if (!register_kvm_events_ops(kvm))
 		goto exit;
 
-	init_kvm_event_record(kvm);
 	setup_pager();
 
 	kvm_hists__init();

tools/perf/util/kvm-stat.h

···
 
 struct kvm_event {
 	struct list_head hash_entry;
-	struct rb_node rb;
 
 	struct perf_kvm_stat *perf_kvm;
 	struct event_key key;
···
 	const char *reason;
 };
 
-#define EVENTS_BITS		12
-#define EVENTS_CACHE_SIZE	(1UL << EVENTS_BITS)
-
 struct perf_kvm_stat {
 	struct perf_tool    tool;
 	struct record_opts  opts;
···
 
 	struct kvm_events_ops *events_ops;
 	key_cmp_fun compare;
-	struct list_head kvm_events_cache[EVENTS_CACHE_SIZE];
 
 	u64 total_time;
 	u64 total_count;
···
 	u64 duration;
 
 	struct intlist *pid_list;
-
-	struct rb_root result;
 
 	int timerfd;
 	unsigned int display_time;