From c8446b9bdabcb0caa61bb341bd73c58f7104b503 Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Fri, 14 May 2010 10:36:42 -0300
Subject: [PATCH 1/4] perf hist: Make event__totals per hists
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This is one more thing that started global but are more useful per hist
or per session.

Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-annotate.c |  2 +-
 tools/perf/builtin-report.c   |  8 +++++++-
 tools/perf/util/event.c       | 17 +++++++++++++++++
 tools/perf/util/event.h       |  2 ++
 tools/perf/util/hist.c        | 21 ++++++++++++++++++++
 tools/perf/util/hist.h        |  6 ++++++
 tools/perf/util/session.c     | 36 ++---------------------------------
 tools/perf/util/session.h     |  8 ++++++--
 8 files changed, 62 insertions(+), 38 deletions(-)

diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index fd1b786c8f35..77bcc9b130f5 100644
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -365,7 +365,7 @@ static int __cmd_annotate(void)
 		goto out_delete;
 
 	if (dump_trace) {
-		event__print_totals();
+		perf_session__fprintf_nr_events(session, stdout);
 		goto out_delete;
 	}
 
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 04de3387de3f..f13cda1ef059 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -139,6 +139,12 @@ static int add_event_total(struct perf_session *session,
 		return -ENOMEM;
 
 	hists->stats.total += data->period;
+	/*
+	 * FIXME: add_event_total should be moved from here to
+	 * perf_session__process_event so that the proper hist is passed to
+	 * the event_op methods.
+	 */
+	hists__inc_nr_events(hists, PERF_RECORD_SAMPLE);
 	session->hists.stats.total += data->period;
 	return 0;
 }
@@ -293,7 +299,7 @@ static int __cmd_report(void)
 		goto out_delete;
 
 	if (dump_trace) {
-		event__print_totals();
+		perf_session__fprintf_nr_events(session, stdout);
 		goto out_delete;
 	}
 
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index cce006ec8f05..3e8fec173041 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -7,6 +7,23 @@
 #include "strlist.h"
 #include "thread.h"
 
+const char *event__name[] = {
+	[0]			 = "TOTAL",
+	[PERF_RECORD_MMAP]	 = "MMAP",
+	[PERF_RECORD_LOST]	 = "LOST",
+	[PERF_RECORD_COMM]	 = "COMM",
+	[PERF_RECORD_EXIT]	 = "EXIT",
+	[PERF_RECORD_THROTTLE]	 = "THROTTLE",
+	[PERF_RECORD_UNTHROTTLE] = "UNTHROTTLE",
+	[PERF_RECORD_FORK]	 = "FORK",
+	[PERF_RECORD_READ]	 = "READ",
+	[PERF_RECORD_SAMPLE]	 = "SAMPLE",
+	[PERF_RECORD_HEADER_ATTR]	 = "ATTR",
+	[PERF_RECORD_HEADER_EVENT_TYPE]	 = "EVENT_TYPE",
+	[PERF_RECORD_HEADER_TRACING_DATA]	 = "TRACING_DATA",
+	[PERF_RECORD_HEADER_BUILD_ID]	 = "BUILD_ID",
+};
+
 static pid_t event__synthesize_comm(pid_t pid, int full,
 				    event__handler_t process,
 				    struct perf_session *session)
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 48c2cc9dae4f..8577085db067 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -160,4 +160,6 @@ int event__preprocess_sample(const event_t *self, struct perf_session *session,
 			     struct addr_location *al, symbol_filter_t filter);
 int event__parse_sample(event_t *event, u64 type, struct sample_data *data);
 
+extern const char *event__name[];
+
 #endif /* __PERF_RECORD_H */
diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index 5dc4f8429eda..1614ad710046 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -1028,3 +1028,24 @@ int hist_entry__annotate(struct hist_entry *self, struct list_head *head)
 	pclose(file);
 	return 0;
 }
+
+void hists__inc_nr_events(struct hists *self, u32 type)
+{
+	++self->hists.stats.nr_events[0];
+	++self->hists.stats.nr_events[type];
+}
+
+size_t hists__fprintf_nr_events(struct hists *self, FILE *fp)
+{
+	int i;
+	size_t ret = 0;
+
+	for (i = 0; i < PERF_RECORD_HEADER_MAX; ++i) {
+		if (!event__name[i])
+			continue;
+		ret += fprintf(fp, "%10s events: %10d\n",
+			       event__name[i], self->stats.nr_events[i]);
+	}
+
+	return ret;
+}
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index 0b4c8df914bd..97b8962ff69a 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -40,6 +40,8 @@ struct sym_priv {
 struct events_stats {
 	u64 total;
 	u64 lost;
+	u32 nr_events[PERF_RECORD_HEADER_MAX];
+	u32 nr_unknown_events;
 };
 
 struct hists {
@@ -68,6 +70,10 @@ void hist_entry__free(struct hist_entry *);
 
 void hists__output_resort(struct hists *self);
 void hists__collapse_resort(struct hists *self);
+
+void hists__inc_nr_events(struct hists *self, u32 type);
+size_t hists__fprintf_nr_events(struct hists *self, FILE *fp);
+
 size_t hists__fprintf(struct hists *self, struct hists *pair,
 		      bool show_displacement, FILE *fp);
 
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 72a7f6ae0293..7231f6b19fb4 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -94,7 +94,6 @@ struct perf_session *perf_session__new(const char *filename, int mode, bool forc
 	self->mmap_window = 32;
 	self->cwd = NULL;
 	self->cwdlen = 0;
-	self->unknown_events = 0;
 	self->machines = RB_ROOT;
 	self->repipe = repipe;
 	INIT_LIST_HEAD(&self->ordered_samples.samples_head);
@@ -241,36 +240,6 @@ static void perf_event_ops__fill_defaults(struct perf_event_ops *handler)
 	}
 }
 
-static const char *event__name[] = {
-	[0]			 = "TOTAL",
-	[PERF_RECORD_MMAP]	 = "MMAP",
-	[PERF_RECORD_LOST]	 = "LOST",
-	[PERF_RECORD_COMM]	 = "COMM",
-	[PERF_RECORD_EXIT]	 = "EXIT",
-	[PERF_RECORD_THROTTLE]	 = "THROTTLE",
-	[PERF_RECORD_UNTHROTTLE] = "UNTHROTTLE",
-	[PERF_RECORD_FORK]	 = "FORK",
-	[PERF_RECORD_READ]	 = "READ",
-	[PERF_RECORD_SAMPLE]	 = "SAMPLE",
-	[PERF_RECORD_HEADER_ATTR]	 = "ATTR",
-	[PERF_RECORD_HEADER_EVENT_TYPE]	 = "EVENT_TYPE",
-	[PERF_RECORD_HEADER_TRACING_DATA]	 = "TRACING_DATA",
-	[PERF_RECORD_HEADER_BUILD_ID]	 = "BUILD_ID",
-};
-
-unsigned long event__total[PERF_RECORD_HEADER_MAX];
-
-void event__print_totals(void)
-{
-	int i;
-	for (i = 0; i < PERF_RECORD_HEADER_MAX; ++i) {
-		if (!event__name[i])
-			continue;
-		pr_info("%10s events: %10ld\n",
-			event__name[i], event__total[i]);
-	}
-}
-
 void mem_bswap_64(void *src, int byte_size)
 {
 	u64 *m = src;
@@ -580,8 +549,7 @@ static int perf_session__process_event(struct perf_session *self,
 		dump_printf("%#Lx [%#x]: PERF_RECORD_%s",
 			    offset + head, event->header.size,
 			    event__name[event->header.type]);
-		++event__total[0];
-		++event__total[event->header.type];
+		hists__inc_nr_events(self, event->header.type);
 	}
 
 	if (self->header.needs_swap && event__swap_ops[event->header.type])
@@ -619,7 +587,7 @@ static int perf_session__process_event(struct perf_session *self,
 	case PERF_RECORD_FINISHED_ROUND:
 		return ops->finished_round(event, self, ops);
 	default:
-		self->unknown_events++;
+		++self->hists.stats.nr_unknown_events;
 		return -1;
 	}
 }
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index ce00fa6cdeda..e7fce486ebe2 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -30,8 +30,6 @@ struct perf_session {
 	struct machine		host_machine;
 	struct rb_root		machines;
 	struct rb_root		hists_tree;
-	unsigned long		event_total[PERF_RECORD_MAX];
-	unsigned long		unknown_events;
 	/*
 	 * FIXME: should point to the first entry in hists_tree and
 	 *        be a hists instance. Right now its only 'report'
@@ -140,4 +138,10 @@ size_t perf_session__fprintf_dsos_buildid(struct perf_session *self, FILE *fp,
 {
 	return machines__fprintf_dsos_buildid(&self->machines, fp, with_hits);
 }
+
+static inline
+size_t perf_session__fprintf_nr_events(struct perf_session *self, FILE *fp)
+{
+	return hists__fprintf_nr_events(&self->hists, fp);
+}
 #endif /* __PERF_SESSION_H */

From cee75ac7ecc27084accdb9d9d6fde65a09f047ae Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Fri, 14 May 2010 13:16:55 -0300
Subject: [PATCH 2/4] perf hist: Clarify events_stats fields usage
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The events_stats.total field is too generic, rename it to .total_period,
and also add a comment explaining that it is the sum of all the .period
fields in samples, that is needed because we use auto-freq to avoid
sampling artifacts.

Ditto for events_stats.lost, that is the sum of all lost_event.lost
fields, i.e. the number of events the kernel dropped.

Looking at the users, builtin-sched.c can make use of these fields and
stop doing it again.

Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-diff.c   |  2 +-
 tools/perf/builtin-report.c |  8 ++++----
 tools/perf/builtin-sched.c  | 17 ++++++-----------
 tools/perf/builtin-trace.c  |  2 +-
 tools/perf/util/event.c     |  2 +-
 tools/perf/util/hist.c      | 20 ++++++++++----------
 tools/perf/util/hist.h      | 16 ++++++++++++++--
 tools/perf/util/newt.c      |  6 +++---
 tools/perf/util/session.c   |  2 +-
 9 files changed, 41 insertions(+), 34 deletions(-)

diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 3a95a0260a5b..6dd4bdae8a87 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -54,7 +54,7 @@ static int diff__process_sample_event(event_t *event, struct perf_session *sessi
 		return -1;
 	}
 
-	session->hists.stats.total += data.period;
+	session->hists.stats.total_period += data.period;
 	return 0;
 }
 
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index f13cda1ef059..b8f47ded6287 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -138,14 +138,14 @@ static int add_event_total(struct perf_session *session,
 	if (!hists)
 		return -ENOMEM;
 
-	hists->stats.total += data->period;
+	hists->stats.total_period += data->period;
 	/*
 	 * FIXME: add_event_total should be moved from here to
 	 * perf_session__process_event so that the proper hist is passed to
 	 * the event_op methods.
 	 */
 	hists__inc_nr_events(hists, PERF_RECORD_SAMPLE);
-	session->hists.stats.total += data->period;
+	session->hists.stats.total_period += data->period;
 	return 0;
 }
 
@@ -322,10 +322,10 @@ static int __cmd_report(void)
 			if (rb_first(&session->hists.entries) ==
 			    rb_last(&session->hists.entries))
 				fprintf(stdout, "# Samples: %Ld\n#\n",
-					hists->stats.total);
+					hists->stats.total_period);
 			else
 				fprintf(stdout, "# Samples: %Ld %s\n#\n",
-					hists->stats.total,
+					hists->stats.total_period,
 					__event_name(hists->type, hists->config));
 
 			hists__fprintf(hists, NULL, false, stdout);
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index aef6ed0e119c..be7bc9264710 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -1641,19 +1641,10 @@ static int process_sample_event(event_t *event, struct perf_session *session)
 	return 0;
 }
 
-static int process_lost_event(event_t *event __used,
-			      struct perf_session *session __used)
-{
-	nr_lost_chunks++;
-	nr_lost_events += event->lost.lost;
-
-	return 0;
-}
-
 static struct perf_event_ops event_ops = {
 	.sample			= process_sample_event,
 	.comm			= event__process_comm,
-	.lost			= process_lost_event,
+	.lost			= event__process_lost,
 	.ordered_samples	= true,
 };
 
@@ -1664,8 +1655,12 @@ static int read_events(void)
 	if (session == NULL)
 		return -ENOMEM;
 
-	if (perf_session__has_traces(session, "record -R"))
+	if (perf_session__has_traces(session, "record -R")) {
 		err = perf_session__process_events(session, &event_ops);
+		nr_events      = session->hists.stats.nr_events[0];
+		nr_lost_events = session->hists.stats.total_lost;
+		nr_lost_chunks = session->hists.stats.nr_events[PERF_RECORD_LOST];
+	}
 
 	perf_session__delete(session);
 	return err;
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 95fcb0517a9d..dddf3f01b5ab 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -109,7 +109,7 @@ static int process_sample_event(event_t *event, struct perf_session *session)
 					     data.time, thread->comm);
 	}
 
-	session->hists.stats.total += data.period;
+	session->hists.stats.total_period += data.period;
 	return 0;
 }
 
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 3e8fec173041..50771b5813ee 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -385,7 +385,7 @@ int event__process_comm(event_t *self, struct perf_session *session)
 int event__process_lost(event_t *self, struct perf_session *session)
 {
 	dump_printf(": id:%Ld: lost:%Ld\n", self->lost.id, self->lost.lost);
-	session->hists.stats.lost += self->lost.lost;
+	session->hists.stats.total_lost += self->lost.lost;
 	return 0;
 }
 
diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index 1614ad710046..c59224518083 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -239,7 +239,7 @@ void hists__output_resort(struct hists *self)
 	struct hist_entry *n;
 	u64 min_callchain_hits;
 
-	min_callchain_hits = self->stats.total * (callchain_param.min_percent / 100);
+	min_callchain_hits = self->stats.total_period * (callchain_param.min_percent / 100);
 
 	tmp = RB_ROOT;
 	next = rb_first(&self->entries);
@@ -525,7 +525,7 @@ int hist_entry__snprintf(struct hist_entry *self, char *s, size_t size,
 
 	if (pair_hists) {
 		count = self->pair ? self->pair->count : 0;
-		total = pair_hists->stats.total;
+		total = pair_hists->stats.total_period;
 		count_sys = self->pair ? self->pair->count_sys : 0;
 		count_us = self->pair ? self->pair->count_us : 0;
 		count_guest_sys = self->pair ? self->pair->count_guest_sys : 0;
@@ -769,10 +769,10 @@ print_entries:
 			++position;
 		}
 		ret += hist_entry__fprintf(h, pair, show_displacement,
-					   displacement, fp, self->stats.total);
+					   displacement, fp, self->stats.total_period);
 
 		if (symbol_conf.use_callchain)
-			ret += hist_entry__fprintf_callchain(h, fp, self->stats.total);
+			ret += hist_entry__fprintf_callchain(h, fp, self->stats.total_period);
 
 		if (h->ms.map == NULL && verbose > 1) {
 			__map_groups__fprintf_maps(&h->thread->mg,
@@ -795,7 +795,7 @@ void hists__filter_by_dso(struct hists *self, const struct dso *dso)
 {
 	struct rb_node *nd;
 
-	self->nr_entries = self->stats.total = 0;
+	self->nr_entries = self->stats.total_period = 0;
 	self->max_sym_namelen = 0;
 
 	for (nd = rb_first(&self->entries); nd; nd = rb_next(nd)) {
@@ -812,7 +812,7 @@ void hists__filter_by_dso(struct hists *self, const struct dso *dso)
 		h->filtered &= ~(1 << HIST_FILTER__DSO);
 		if (!h->filtered) {
 			++self->nr_entries;
-			self->stats.total += h->count;
+			self->stats.total_period += h->count;
 			if (h->ms.sym &&
 			    self->max_sym_namelen < h->ms.sym->namelen)
 				self->max_sym_namelen = h->ms.sym->namelen;
@@ -824,7 +824,7 @@ void hists__filter_by_thread(struct hists *self, const struct thread *thread)
 {
 	struct rb_node *nd;
 
-	self->nr_entries = self->stats.total = 0;
+	self->nr_entries = self->stats.total_period = 0;
 	self->max_sym_namelen = 0;
 
 	for (nd = rb_first(&self->entries); nd; nd = rb_next(nd)) {
@@ -837,7 +837,7 @@ void hists__filter_by_thread(struct hists *self, const struct thread *thread)
 		h->filtered &= ~(1 << HIST_FILTER__THREAD);
 		if (!h->filtered) {
 			++self->nr_entries;
-			self->stats.total += h->count;
+			self->stats.total_period += h->count;
 			if (h->ms.sym &&
 			    self->max_sym_namelen < h->ms.sym->namelen)
 				self->max_sym_namelen = h->ms.sym->namelen;
@@ -1031,8 +1031,8 @@ int hist_entry__annotate(struct hist_entry *self, struct list_head *head)
 
 void hists__inc_nr_events(struct hists *self, u32 type)
 {
-	++self->hists.stats.nr_events[0];
-	++self->hists.stats.nr_events[type];
+	++self->stats.nr_events[0];
+	++self->stats.nr_events[type];
 }
 
 size_t hists__fprintf_nr_events(struct hists *self, FILE *fp)
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index 97b8962ff69a..da6b84814a50 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -37,9 +37,21 @@ struct sym_priv {
 	struct sym_ext	*ext;
 };
 
+/*
+ * The kernel collects the number of events it couldn't send in a stretch and
+ * when possible sends this number in a PERF_RECORD_LOST event. The number of
+ * such "chunks" of lost events is stored in .nr_events[PERF_EVENT_LOST] while
+ * total_lost tells exactly how many events the kernel in fact lost, i.e. it is
+ * the sum of all struct lost_event.lost fields reported.
+ *
+ * The total_period is needed because by default auto-freq is used, so
+ * multipling nr_events[PERF_EVENT_SAMPLE] by a frequency isn't possible to get
+ * the total number of low level events, it is necessary to to sum all struct
+ * sample_event.period and stash the result in total_period.
+ */
 struct events_stats {
-	u64 total;
-	u64 lost;
+	u64 total_period;
+	u64 total_lost;
 	u32 nr_events[PERF_RECORD_HEADER_MAX];
 	u32 nr_unknown_events;
 };
diff --git a/tools/perf/util/newt.c b/tools/perf/util/newt.c
index ba6acd04c082..010bacf40163 100644
--- a/tools/perf/util/newt.c
+++ b/tools/perf/util/newt.c
@@ -689,7 +689,7 @@ static int hist_browser__populate(struct hist_browser *self, struct hists *hists
 	}
 
 	snprintf(str, sizeof(str), "Samples: %Ld                            ",
-		 hists->stats.total);
+		 hists->stats.total_period);
 	newtDrawRootText(0, 0, str);
 
 	newtGetScreenSize(NULL, &rows);
@@ -718,12 +718,12 @@ static int hist_browser__populate(struct hist_browser *self, struct hists *hists
 		if (h->filtered)
 			continue;
 
-		len = hist_entry__append_browser(h, self->tree, hists->stats.total);
+		len = hist_entry__append_browser(h, self->tree, hists->stats.total_period);
 		if (len > max_len)
 			max_len = len;
 		if (symbol_conf.use_callchain)
 			hist_entry__append_callchain_browser(h, self->tree,
-							     hists->stats.total, idx++);
+							     hists->stats.total_period, idx++);
 		++curr_hist;
 		if (curr_hist % 5)
 			ui_progress__update(progress, curr_hist);
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 7231f6b19fb4..25bfca4f10f0 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -549,7 +549,7 @@ static int perf_session__process_event(struct perf_session *self,
 		dump_printf("%#Lx [%#x]: PERF_RECORD_%s",
 			    offset + head, event->header.size,
 			    event__name[event->header.type]);
-		hists__inc_nr_events(self, event->header.type);
+		hists__inc_nr_events(&self->hists, event->header.type);
 	}
 
 	if (self->header.needs_swap && event__swap_ops[event->header.type])

From c82ee828aa20487d254a5225d256cd422acee459 Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Fri, 14 May 2010 14:19:35 -0300
Subject: [PATCH 3/4] perf report: Report number of events, not samples
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Number of samples is meaningless after we switched to auto-freq, so
report the number of events, i.e. not the sum of the different periods,
but the number PERF_RECORD_SAMPLE emitted by the kernel.

While doing this I noticed that naming "count" to the sum of all the
event periods can be confusing, so rename it to .period, just like in
struct sample.data, so that we become more consistent.

This helps with the next step, that was to record in struct hist_entry
the number of sample events for each instance, we need that because we
use it to generate the number of events when applying filters to the
tree of hist entries like it is being done in the TUI report browser.

Suggested-by: Ingo Molnar <mingo@elte.hu>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-diff.c   |  6 +--
 tools/perf/builtin-report.c | 32 +++++++++-----
 tools/perf/util/hist.c      | 88 ++++++++++++++++++++-----------------
 tools/perf/util/hist.h      |  2 +-
 tools/perf/util/newt.c      |  8 ++--
 tools/perf/util/sort.h      | 11 ++---
 tools/perf/util/util.c      | 22 ++++++++++
 tools/perf/util/util.h      |  1 +
 8 files changed, 107 insertions(+), 63 deletions(-)

diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 6dd4bdae8a87..a6e2fdc7a04e 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -23,9 +23,9 @@ static bool  force;
 static bool show_displacement;
 
 static int hists__add_entry(struct hists *self,
-			    struct addr_location *al, u64 count)
+			    struct addr_location *al, u64 period)
 {
-	if (__hists__add_entry(self, al, NULL, count) != NULL)
+	if (__hists__add_entry(self, al, NULL, period) != NULL)
 		return 0;
 	return -ENOMEM;
 }
@@ -50,7 +50,7 @@ static int diff__process_sample_event(event_t *event, struct perf_session *sessi
 	event__parse_sample(event, session->sample_type, &data);
 
 	if (hists__add_entry(&session->hists, &al, data.period)) {
-		pr_warning("problem incrementing symbol count, skipping event\n");
+		pr_warning("problem incrementing symbol period, skipping event\n");
 		return -1;
 	}
 
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index b8f47ded6287..68265120ee07 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -188,14 +188,14 @@ static int process_sample_event(event_t *event, struct perf_session *session)
 		return 0;
 
 	if (perf_session__add_hist_entry(session, &al, &data)) {
-		pr_debug("problem incrementing symbol count, skipping event\n");
+		pr_debug("problem incrementing symbol period, skipping event\n");
 		return -1;
 	}
 
 	attr = perf_header__find_attr(data.id, &session->header);
 
 	if (add_event_total(session, &data, attr)) {
-		pr_debug("problem adding event count\n");
+		pr_debug("problem adding event period\n");
 		return -1;
 	}
 
@@ -269,11 +269,25 @@ static struct perf_event_ops event_ops = {
 
 extern volatile int session_done;
 
-static void sig_handler(int sig __attribute__((__unused__)))
+static void sig_handler(int sig __used)
 {
 	session_done = 1;
 }
 
+static size_t hists__fprintf_nr_sample_events(struct hists *self,
+					      const char *evname, FILE *fp)
+{
+	size_t ret;
+	char unit;
+	unsigned long nr_events = self->stats.nr_events[PERF_RECORD_SAMPLE];
+
+	nr_events = convert_unit(nr_events, &unit);
+	ret = fprintf(fp, "# Events: %lu%c", nr_events, unit);
+	if (evname != NULL)
+		ret += fprintf(fp, " %s", evname);
+	return ret + fprintf(fp, "\n#\n");
+}
+
 static int __cmd_report(void)
 {
 	int ret = -EINVAL;
@@ -319,14 +333,12 @@ static int __cmd_report(void)
 		if (use_browser)
 			hists__browse(hists, help, input_name);
 		else {
-			if (rb_first(&session->hists.entries) ==
+			const char *evname = NULL;
+			if (rb_first(&session->hists.entries) !=
 			    rb_last(&session->hists.entries))
-				fprintf(stdout, "# Samples: %Ld\n#\n",
-					hists->stats.total_period);
-			else
-				fprintf(stdout, "# Samples: %Ld %s\n#\n",
-					hists->stats.total_period,
-					__event_name(hists->type, hists->config));
+				evname = __event_name(hists->type, hists->config);
+
+			hists__fprintf_nr_sample_events(hists, evname, stdout);
 
 			hists__fprintf(hists, NULL, false, stdout);
 			fprintf(stdout, "\n\n");
diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index c59224518083..f75c5f62401c 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -9,21 +9,21 @@ struct callchain_param	callchain_param = {
 	.min_percent = 0.5
 };
 
-static void hist_entry__add_cpumode_count(struct hist_entry *self,
-					  unsigned int cpumode, u64 count)
+static void hist_entry__add_cpumode_period(struct hist_entry *self,
+					   unsigned int cpumode, u64 period)
 {
 	switch (cpumode) {
 	case PERF_RECORD_MISC_KERNEL:
-		self->count_sys += count;
+		self->period_sys += period;
 		break;
 	case PERF_RECORD_MISC_USER:
-		self->count_us += count;
+		self->period_us += period;
 		break;
 	case PERF_RECORD_MISC_GUEST_KERNEL:
-		self->count_guest_sys += count;
+		self->period_guest_sys += period;
 		break;
 	case PERF_RECORD_MISC_GUEST_USER:
-		self->count_guest_us += count;
+		self->period_guest_us += period;
 		break;
 	default:
 		break;
@@ -31,7 +31,7 @@ static void hist_entry__add_cpumode_count(struct hist_entry *self,
 }
 
 /*
- * histogram, sorted on item, collects counts
+ * histogram, sorted on item, collects periods
  */
 
 static struct hist_entry *hist_entry__new(struct hist_entry *template)
@@ -41,6 +41,7 @@ static struct hist_entry *hist_entry__new(struct hist_entry *template)
 
 	if (self != NULL) {
 		*self = *template;
+		self->nr_events = 1;
 		if (symbol_conf.use_callchain)
 			callchain_init(self->callchain);
 	}
@@ -57,7 +58,7 @@ static void hists__inc_nr_entries(struct hists *self, struct hist_entry *entry)
 
 struct hist_entry *__hists__add_entry(struct hists *self,
 				      struct addr_location *al,
-				      struct symbol *sym_parent, u64 count)
+				      struct symbol *sym_parent, u64 period)
 {
 	struct rb_node **p = &self->entries.rb_node;
 	struct rb_node *parent = NULL;
@@ -70,7 +71,7 @@ struct hist_entry *__hists__add_entry(struct hists *self,
 		},
 		.ip	= al->addr,
 		.level	= al->level,
-		.count	= count,
+		.period	= period,
 		.parent = sym_parent,
 	};
 	int cmp;
@@ -82,7 +83,8 @@ struct hist_entry *__hists__add_entry(struct hists *self,
 		cmp = hist_entry__cmp(&entry, he);
 
 		if (!cmp) {
-			he->count += count;
+			he->period += period;
+			++he->nr_events;
 			goto out;
 		}
 
@@ -99,7 +101,7 @@ struct hist_entry *__hists__add_entry(struct hists *self,
 	rb_insert_color(&he->rb_node, &self->entries);
 	hists__inc_nr_entries(self, he);
 out:
-	hist_entry__add_cpumode_count(he, al->cpumode, count);
+	hist_entry__add_cpumode_period(he, al->cpumode, period);
 	return he;
 }
 
@@ -160,7 +162,7 @@ static bool collapse__insert_entry(struct rb_root *root, struct hist_entry *he)
 		cmp = hist_entry__collapse(iter, he);
 
 		if (!cmp) {
-			iter->count += he->count;
+			iter->period += he->period;
 			hist_entry__free(he);
 			return false;
 		}
@@ -203,7 +205,7 @@ void hists__collapse_resort(struct hists *self)
 }
 
 /*
- * reverse the map, sort on count.
+ * reverse the map, sort on period.
  */
 
 static void __hists__insert_output_entry(struct rb_root *entries,
@@ -222,7 +224,7 @@ static void __hists__insert_output_entry(struct rb_root *entries,
 		parent = *p;
 		iter = rb_entry(parent, struct hist_entry, rb_node);
 
-		if (he->count > iter->count)
+		if (he->period > iter->period)
 			p = &(*p)->rb_left;
 		else
 			p = &(*p)->rb_right;
@@ -288,7 +290,7 @@ static size_t ipchain__fprintf_graph_line(FILE *fp, int depth, int depth_mask,
 }
 
 static size_t ipchain__fprintf_graph(FILE *fp, struct callchain_list *chain,
-				     int depth, int depth_mask, int count,
+				     int depth, int depth_mask, int period,
 				     u64 total_samples, int hits,
 				     int left_margin)
 {
@@ -301,7 +303,7 @@ static size_t ipchain__fprintf_graph(FILE *fp, struct callchain_list *chain,
 			ret += fprintf(fp, "|");
 		else
 			ret += fprintf(fp, " ");
-		if (!count && i == depth - 1) {
+		if (!period && i == depth - 1) {
 			double percent;
 
 			percent = hits * 100.0 / total_samples;
@@ -516,7 +518,7 @@ int hist_entry__snprintf(struct hist_entry *self, char *s, size_t size,
 			 long displacement, bool color, u64 session_total)
 {
 	struct sort_entry *se;
-	u64 count, total, count_sys, count_us, count_guest_sys, count_guest_us;
+	u64 period, total, period_sys, period_us, period_guest_sys, period_guest_us;
 	const char *sep = symbol_conf.field_sep;
 	int ret;
 
@@ -524,57 +526,57 @@ int hist_entry__snprintf(struct hist_entry *self, char *s, size_t size,
 		return 0;
 
 	if (pair_hists) {
-		count = self->pair ? self->pair->count : 0;
+		period = self->pair ? self->pair->period : 0;
 		total = pair_hists->stats.total_period;
-		count_sys = self->pair ? self->pair->count_sys : 0;
-		count_us = self->pair ? self->pair->count_us : 0;
-		count_guest_sys = self->pair ? self->pair->count_guest_sys : 0;
-		count_guest_us = self->pair ? self->pair->count_guest_us : 0;
+		period_sys = self->pair ? self->pair->period_sys : 0;
+		period_us = self->pair ? self->pair->period_us : 0;
+		period_guest_sys = self->pair ? self->pair->period_guest_sys : 0;
+		period_guest_us = self->pair ? self->pair->period_guest_us : 0;
 	} else {
-		count = self->count;
+		period = self->period;
 		total = session_total;
-		count_sys = self->count_sys;
-		count_us = self->count_us;
-		count_guest_sys = self->count_guest_sys;
-		count_guest_us = self->count_guest_us;
+		period_sys = self->period_sys;
+		period_us = self->period_us;
+		period_guest_sys = self->period_guest_sys;
+		period_guest_us = self->period_guest_us;
 	}
 
 	if (total) {
 		if (color)
 			ret = percent_color_snprintf(s, size,
 						     sep ? "%.2f" : "   %6.2f%%",
-						     (count * 100.0) / total);
+						     (period * 100.0) / total);
 		else
 			ret = snprintf(s, size, sep ? "%.2f" : "   %6.2f%%",
-				       (count * 100.0) / total);
+				       (period * 100.0) / total);
 		if (symbol_conf.show_cpu_utilization) {
 			ret += percent_color_snprintf(s + ret, size - ret,
 					sep ? "%.2f" : "   %6.2f%%",
-					(count_sys * 100.0) / total);
+					(period_sys * 100.0) / total);
 			ret += percent_color_snprintf(s + ret, size - ret,
 					sep ? "%.2f" : "   %6.2f%%",
-					(count_us * 100.0) / total);
+					(period_us * 100.0) / total);
 			if (perf_guest) {
 				ret += percent_color_snprintf(s + ret,
 						size - ret,
 						sep ? "%.2f" : "   %6.2f%%",
-						(count_guest_sys * 100.0) /
+						(period_guest_sys * 100.0) /
 								total);
 				ret += percent_color_snprintf(s + ret,
 						size - ret,
 						sep ? "%.2f" : "   %6.2f%%",
-						(count_guest_us * 100.0) /
+						(period_guest_us * 100.0) /
 								total);
 			}
 		}
 	} else
-		ret = snprintf(s, size, sep ? "%lld" : "%12lld ", count);
+		ret = snprintf(s, size, sep ? "%lld" : "%12lld ", period);
 
 	if (symbol_conf.show_nr_samples) {
 		if (sep)
-			ret += snprintf(s + ret, size - ret, "%c%lld", *sep, count);
+			ret += snprintf(s + ret, size - ret, "%c%lld", *sep, period);
 		else
-			ret += snprintf(s + ret, size - ret, "%11lld", count);
+			ret += snprintf(s + ret, size - ret, "%11lld", period);
 	}
 
 	if (pair_hists) {
@@ -582,9 +584,9 @@ int hist_entry__snprintf(struct hist_entry *self, char *s, size_t size,
 		double old_percent = 0, new_percent = 0, diff;
 
 		if (total > 0)
-			old_percent = (count * 100.0) / total;
+			old_percent = (period * 100.0) / total;
 		if (session_total > 0)
-			new_percent = (self->count * 100.0) / session_total;
+			new_percent = (self->period * 100.0) / session_total;
 
 		diff = new_percent - old_percent;
 
@@ -796,6 +798,7 @@ void hists__filter_by_dso(struct hists *self, const struct dso *dso)
 	struct rb_node *nd;
 
 	self->nr_entries = self->stats.total_period = 0;
+	self->stats.nr_events[PERF_RECORD_SAMPLE] = 0;
 	self->max_sym_namelen = 0;
 
 	for (nd = rb_first(&self->entries); nd; nd = rb_next(nd)) {
@@ -812,7 +815,8 @@ void hists__filter_by_dso(struct hists *self, const struct dso *dso)
 		h->filtered &= ~(1 << HIST_FILTER__DSO);
 		if (!h->filtered) {
 			++self->nr_entries;
-			self->stats.total_period += h->count;
+			self->stats.total_period += h->period;
+			self->stats.nr_events[PERF_RECORD_SAMPLE] += h->nr_events;
 			if (h->ms.sym &&
 			    self->max_sym_namelen < h->ms.sym->namelen)
 				self->max_sym_namelen = h->ms.sym->namelen;
@@ -825,6 +829,7 @@ void hists__filter_by_thread(struct hists *self, const struct thread *thread)
 	struct rb_node *nd;
 
 	self->nr_entries = self->stats.total_period = 0;
+	self->stats.nr_events[PERF_RECORD_SAMPLE] = 0;
 	self->max_sym_namelen = 0;
 
 	for (nd = rb_first(&self->entries); nd; nd = rb_next(nd)) {
@@ -837,7 +842,8 @@ void hists__filter_by_thread(struct hists *self, const struct thread *thread)
 		h->filtered &= ~(1 << HIST_FILTER__THREAD);
 		if (!h->filtered) {
 			++self->nr_entries;
-			self->stats.total_period += h->count;
+			self->stats.total_period += h->period;
+			self->stats.nr_events[PERF_RECORD_SAMPLE] += h->nr_events;
 			if (h->ms.sym &&
 			    self->max_sym_namelen < h->ms.sym->namelen)
 				self->max_sym_namelen = h->ms.sym->namelen;
@@ -881,7 +887,7 @@ int hist_entry__inc_addr_samples(struct hist_entry *self, u64 ip)
 	h->sum++;
 	h->ip[offset]++;
 
-	pr_debug3("%#Lx %s: count++ [ip: %#Lx, %#Lx] => %Ld\n", self->ms.sym->start,
+	pr_debug3("%#Lx %s: period++ [ip: %#Lx, %#Lx] => %Ld\n", self->ms.sym->start,
 		  self->ms.sym->name, ip, ip - self->ms.sym->start, h->ip[offset]);
 	return 0;
 }
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index da6b84814a50..6f17dcd8412c 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -69,7 +69,7 @@ struct hists {
 
 struct hist_entry *__hists__add_entry(struct hists *self,
 				      struct addr_location *al,
-				      struct symbol *parent, u64 count);
+				      struct symbol *parent, u64 period);
 extern int64_t hist_entry__cmp(struct hist_entry *, struct hist_entry *);
 extern int64_t hist_entry__collapse(struct hist_entry *, struct hist_entry *);
 int hist_entry__fprintf(struct hist_entry *self, struct hists *pair_hists,
diff --git a/tools/perf/util/newt.c b/tools/perf/util/newt.c
index 010bacf40163..3402453812b3 100644
--- a/tools/perf/util/newt.c
+++ b/tools/perf/util/newt.c
@@ -680,16 +680,18 @@ static int hist_browser__populate(struct hist_browser *self, struct hists *hists
 	struct ui_progress *progress;
 	struct rb_node *nd;
 	u64 curr_hist = 0;
-	char seq[] = ".";
+	char seq[] = ".", unit;
 	char str[256];
+	unsigned long nr_events = hists->stats.nr_events[PERF_RECORD_SAMPLE];
 
 	if (self->form) {
 		newtFormDestroy(self->form);
 		newtPopWindow();
 	}
 
-	snprintf(str, sizeof(str), "Samples: %Ld                            ",
-		 hists->stats.total_period);
+	nr_events = convert_unit(nr_events, &unit);
+	snprintf(str, sizeof(str), "Events: %lu%c                            ",
+		 nr_events, unit);
 	newtDrawRootText(0, 0, str);
 
 	newtGetScreenSize(NULL, &rows);
diff --git a/tools/perf/util/sort.h b/tools/perf/util/sort.h
index af301acc461c..eab2e0b3b74e 100644
--- a/tools/perf/util/sort.h
+++ b/tools/perf/util/sort.h
@@ -43,14 +43,15 @@ extern enum sort_type sort__first_dimension;
 
 struct hist_entry {
 	struct rb_node		rb_node;
-	u64			count;
-	u64			count_sys;
-	u64			count_us;
-	u64			count_guest_sys;
-	u64			count_guest_us;
+	u64			period;
+	u64			period_sys;
+	u64			period_us;
+	u64			period_guest_sys;
+	u64			period_guest_us;
 	struct map_symbol	ms;
 	struct thread		*thread;
 	u64			ip;
+	u32			nr_events;
 	char			level;
 	u8			filtered;
 	struct symbol		*parent;
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index f9b890fde681..214265674ddd 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -92,3 +92,25 @@ out_close_from:
 out:
 	return err;
 }
+
+unsigned long convert_unit(unsigned long value, char *unit)
+{
+	*unit = ' ';
+
+	if (value > 1000) {
+		value /= 1000;
+		*unit = 'K';
+	}
+
+	if (value > 1000) {
+		value /= 1000;
+		*unit = 'M';
+	}
+
+	if (value > 1000) {
+		value /= 1000;
+		*unit = 'G';
+	}
+
+	return value;
+}
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index fbf45d1b26f7..0795bf304b19 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -423,6 +423,7 @@ char **argv_split(const char *str, int *argcp);
 void argv_free(char **argv);
 bool strglobmatch(const char *str, const char *pat);
 bool strlazymatch(const char *str, const char *pat);
+unsigned long convert_unit(unsigned long value, char *unit);
 
 #define _STR(x) #x
 #define STR(x) _STR(x)

From 3e1bbdc3a721f4b1ed44f4554402a8dbc60fa97f Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Fri, 14 May 2010 20:05:21 -0300
Subject: [PATCH 4/4] perf newt: Make <- zoom out filters
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

After we use the filters to zoom into DSOs or threads, we can use <-
(left arrow) to zoom out from the last filter applied.

It is still possible to zoom out of order by using the popup menu.

With this we now have the zoom out operation on the browsing fast path,
by allowing fast navigation using just the four arrors and the enter key
to expand collapse callchains.

Suggested-by: Ingo Molnar <mingo@elte.hu>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/Makefile      |  2 ++
 tools/perf/util/newt.c   | 34 ++++++++++++++++--
 tools/perf/util/pstack.c | 75 ++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/pstack.h | 12 +++++++
 4 files changed, 120 insertions(+), 3 deletions(-)
 create mode 100644 tools/perf/util/pstack.c
 create mode 100644 tools/perf/util/pstack.h

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 9c4dc30cdc13..a9281cca4114 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -416,6 +416,7 @@ LIB_H += util/thread.h
 LIB_H += util/trace-event.h
 LIB_H += util/probe-finder.h
 LIB_H += util/probe-event.h
+LIB_H += util/pstack.h
 LIB_H += util/cpumap.h
 
 LIB_OBJS += $(OUTPUT)util/abspath.o
@@ -451,6 +452,7 @@ LIB_OBJS += $(OUTPUT)util/callchain.o
 LIB_OBJS += $(OUTPUT)util/values.o
 LIB_OBJS += $(OUTPUT)util/debug.o
 LIB_OBJS += $(OUTPUT)util/map.o
+LIB_OBJS += $(OUTPUT)util/pstack.o
 LIB_OBJS += $(OUTPUT)util/session.o
 LIB_OBJS += $(OUTPUT)util/thread.o
 LIB_OBJS += $(OUTPUT)util/trace-event-parse.o
diff --git a/tools/perf/util/newt.c b/tools/perf/util/newt.c
index 3402453812b3..e74df1240ef6 100644
--- a/tools/perf/util/newt.c
+++ b/tools/perf/util/newt.c
@@ -9,6 +9,7 @@
 
 #include "cache.h"
 #include "hist.h"
+#include "pstack.h"
 #include "session.h"
 #include "sort.h"
 #include "symbol.h"
@@ -750,6 +751,7 @@ static int hist_browser__populate(struct hist_browser *self, struct hists *hists
 	newtFormAddHotKey(self->form, 'A');
 	newtFormAddHotKey(self->form, 'a');
 	newtFormAddHotKey(self->form, NEWT_KEY_RIGHT);
+	newtFormAddHotKey(self->form, NEWT_KEY_LEFT);
 	newtFormAddComponents(self->form, self->tree, NULL);
 	self->selection = newt__symbol_tree_get_current(self->tree);
 
@@ -801,6 +803,7 @@ static int hist_browser__title(char *bf, size_t size, const char *input_name,
 int hists__browse(struct hists *self, const char *helpline, const char *input_name)
 {
 	struct hist_browser *browser = hist_browser__new();
+	struct pstack *fstack = pstack__new(2);
 	const struct thread *thread_filter = NULL;
 	const struct dso *dso_filter = NULL;
 	struct newtExitStruct es;
@@ -810,12 +813,16 @@ int hists__browse(struct hists *self, const char *helpline, const char *input_na
 	if (browser == NULL)
 		return -1;
 
+	fstack = pstack__new(2);
+	if (fstack == NULL)
+		goto out;
+
 	ui_helpline__push(helpline);
 
 	hist_browser__title(msg, sizeof(msg), input_name,
 			    dso_filter, thread_filter);
 	if (hist_browser__populate(browser, self, msg) < 0)
-		goto out;
+		goto out_free_stack;
 
 	while (1) {
 		const struct thread *thread;
@@ -836,6 +843,19 @@ int hists__browse(struct hists *self, const char *helpline, const char *input_na
 				else
 					continue;
 			}
+
+			if (es.u.key == NEWT_KEY_LEFT) {
+				const void *top;
+
+				if (pstack__empty(fstack))
+					continue;
+				top = pstack__pop(fstack);
+				if (top == &dso_filter)
+					goto zoom_out_dso;
+				if (top == &thread_filter)
+					goto zoom_out_thread;
+				continue;
+			}
 		}
 
 		if (browser->selection->sym != NULL &&
@@ -888,12 +908,15 @@ do_annotate:
 			hist_entry__annotate_browser(he);
 		} else if (choice == zoom_dso) {
 			if (dso_filter) {
+				pstack__remove(fstack, &dso_filter);
+zoom_out_dso:
 				ui_helpline__pop();
 				dso_filter = NULL;
 			} else {
-				ui_helpline__fpush("To zoom out press -> + \"Zoom out of %s DSO\"",
+				ui_helpline__fpush("To zoom out press <- or -> + \"Zoom out of %s DSO\"",
 						   dso->kernel ? "the Kernel" : dso->short_name);
 				dso_filter = dso;
+				pstack__push(fstack, &dso_filter);
 			}
 			hists__filter_by_dso(self, dso_filter);
 			hist_browser__title(msg, sizeof(msg), input_name,
@@ -902,13 +925,16 @@ do_annotate:
 				goto out;
 		} else if (choice == zoom_thread) {
 			if (thread_filter) {
+				pstack__remove(fstack, &thread_filter);
+zoom_out_thread:
 				ui_helpline__pop();
 				thread_filter = NULL;
 			} else {
-				ui_helpline__fpush("To zoom out press -> + \"Zoom out of %s(%d) thread\"",
+				ui_helpline__fpush("To zoom out press <- or -> + \"Zoom out of %s(%d) thread\"",
 						   thread->comm_set ? thread->comm : "",
 						   thread->pid);
 				thread_filter = thread;
+				pstack__push(fstack, &thread_filter);
 			}
 			hists__filter_by_thread(self, thread_filter);
 			hist_browser__title(msg, sizeof(msg), input_name,
@@ -918,6 +944,8 @@ do_annotate:
 		}
 	}
 	err = 0;
+out_free_stack:
+	pstack__delete(fstack);
 out:
 	hist_browser__delete(browser);
 	return err;
diff --git a/tools/perf/util/pstack.c b/tools/perf/util/pstack.c
new file mode 100644
index 000000000000..13d36faf64eb
--- /dev/null
+++ b/tools/perf/util/pstack.c
@@ -0,0 +1,75 @@
+/*
+ * Simple pointer stack
+ *
+ * (c) 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
+ */
+
+#include "util.h"
+#include "pstack.h"
+#include <linux/kernel.h>
+#include <stdlib.h>
+
+struct pstack {
+	unsigned short	top;
+	unsigned short	max_nr_entries;
+	void		*entries[0];
+};
+
+struct pstack *pstack__new(unsigned short max_nr_entries)
+{
+	struct pstack *self = zalloc((sizeof(*self) +
+				     max_nr_entries * sizeof(void *)));
+	if (self != NULL)
+		self->max_nr_entries = max_nr_entries;
+	return self;
+}
+
+void pstack__delete(struct pstack *self)
+{
+	free(self);
+}
+
+bool pstack__empty(const struct pstack *self)
+{
+	return self->top == 0;
+}
+
+void pstack__remove(struct pstack *self, void *key)
+{
+	unsigned short i = self->top, last_index = self->top - 1;
+
+	while (i-- != 0) {
+		if (self->entries[i] == key) {
+			if (i < last_index)
+				memmove(self->entries + i,
+					self->entries + i + 1,
+					(last_index - i) * sizeof(void *));
+			--self->top;
+			return;
+		}
+	}
+	pr_err("%s: %p not on the pstack!\n", __func__, key);
+}
+
+void pstack__push(struct pstack *self, void *key)
+{
+	if (self->top == self->max_nr_entries) {
+		pr_err("%s: top=%d, overflow!\n", __func__, self->top);
+		return;
+	}
+	self->entries[self->top++] = key;
+}
+
+void *pstack__pop(struct pstack *self)
+{
+	void *ret;
+
+	if (self->top == 0) {
+		pr_err("%s: underflow!\n", __func__);
+		return NULL;
+	}
+
+	ret = self->entries[--self->top];
+	self->entries[self->top] = NULL;
+	return ret;
+}
diff --git a/tools/perf/util/pstack.h b/tools/perf/util/pstack.h
new file mode 100644
index 000000000000..5ad07023504b
--- /dev/null
+++ b/tools/perf/util/pstack.h
@@ -0,0 +1,12 @@
+#ifndef _PERF_PSTACK_
+#define _PERF_PSTACK_
+
+struct pstack;
+struct pstack *pstack__new(unsigned short max_nr_entries);
+void pstack__delete(struct pstack *self);
+bool pstack__empty(const struct pstack *self);
+void pstack__remove(struct pstack *self, void *key);
+void pstack__push(struct pstack *self, void *key);
+void *pstack__pop(struct pstack *self);
+
+#endif /* _PERF_PSTACK_ */