perf evlist: Store pointer to the cpu and thread maps

So that we don't have to pass it around to the several methods that
needs it, simplifying usage.

There is one case where we don't have the thread/cpu map in advance,
which is in the parsing routines used by top, stat, record, that we have
to wait till all options are parsed to know if a cpu or thread list was
passed to then create those maps.

For that case consolidate the cpu and thread map creation via
perf_evlist__create_maps() out of the code in top and record, while also
providing a perf_evlist__set_maps() for cases where multiple evlists
share maps or for when maps that represent CPU sockets, for instance,
get crafted out of topology information or subsets of threads in a
particular application are to be monitored, providing more granularity
in specifying which cpus and threads to monitor.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

8 files changed, 148 insertions, 119 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index edc3555..07f8d6d 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -42,7 +42,6 @@ static u64			user_interval			= ULLONG_MAX;
 static u64			default_interval		=      0;
 static u64			sample_type;
 
-static struct cpu_map		*cpus;
 static unsigned int		page_size;
 static unsigned int		mmap_pages			=    128;
 static unsigned int		user_freq 			= UINT_MAX;
@@ -58,7 +57,6 @@ static bool			sample_id_all_avail		=   true;
 static bool			system_wide			=  false;
 static pid_t			target_pid			=     -1;
 static pid_t			target_tid			=     -1;
-static struct thread_map	*threads;
 static pid_t			child_pid			=     -1;
 static bool			no_inherit			=  false;
 static enum write_mode_t	write_mode			= WRITE_FORCE;
@@ -189,7 +187,7 @@ static void create_counter(struct perf_evsel *evsel, int cpu)
 	int thread_index;
 	int ret;
 
-	for (thread_index = 0; thread_index < threads->nr; thread_index++) {
+	for (thread_index = 0; thread_index < evsel_list->threads->nr; thread_index++) {
 		h_attr = get_header_attr(attr, evsel->idx);
 		if (h_attr == NULL)
 			die("nomem\n");
@@ -317,7 +315,8 @@ static void open_counters(struct perf_evlist *evlist)
 retry_sample_id:
 		attr->sample_id_all = sample_id_all_avail ? 1 : 0;
 try_again:
-		if (perf_evsel__open(pos, cpus, threads, group, !no_inherit) < 0) {
+		if (perf_evsel__open(pos, evlist->cpus, evlist->threads, group,
+				     !no_inherit) < 0) {
 			int err = errno;
 
 			if (err == EPERM || err == EACCES)
@@ -368,10 +367,10 @@ try_again:
 		}
 	}
 
-	if (perf_evlist__mmap(evlist, cpus, threads, mmap_pages, false) < 0)
+	if (perf_evlist__mmap(evlist, mmap_pages, false) < 0)
 		die("failed to mmap with %d (%s)\n", errno, strerror(errno));
 
-	for (cpu = 0; cpu < cpus->nr; ++cpu) {
+	for (cpu = 0; cpu < evsel_list->cpus->nr; ++cpu) {
 		list_for_each_entry(pos, &evlist->entries, node)
 			create_counter(pos, cpu);
 	}
@@ -450,7 +449,7 @@ static void mmap_read_all(void)
 {
 	int i;
 
-	for (i = 0; i < cpus->nr; i++) {
+	for (i = 0; i < evsel_list->cpus->nr; i++) {
 		if (evsel_list->mmap[i].base)
 			mmap_read(&evsel_list->mmap[i]);
 	}
@@ -584,7 +583,7 @@ static int __cmd_record(int argc, const char **argv)
 		}
 
 		if (!system_wide && target_tid == -1 && target_pid == -1)
-			threads->map[0] = child_pid;
+			evsel_list->threads->map[0] = child_pid;
 
 		close(child_ready_pipe[1]);
 		close(go_pipe[0]);
@@ -718,12 +717,12 @@ static int __cmd_record(int argc, const char **argv)
 		}
 
 		if (done) {
-			for (i = 0; i < cpus->nr; i++) {
+			for (i = 0; i < evsel_list->cpus->nr; i++) {
 				struct perf_evsel *pos;
 
 				list_for_each_entry(pos, &evsel_list->entries, node) {
 					for (thread = 0;
-						thread < threads->nr;
+						thread < evsel_list->threads->nr;
 						thread++)
 						ioctl(FD(pos, i, thread),
 							PERF_EVENT_IOC_DISABLE);
@@ -816,7 +815,7 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
 	int err = -ENOMEM;
 	struct perf_evsel *pos;
 
-	evsel_list = perf_evlist__new();
+	evsel_list = perf_evlist__new(NULL, NULL);
 	if (evsel_list == NULL)
 		return -ENOMEM;
 
@@ -850,28 +849,19 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
 	if (target_pid != -1)
 		target_tid = target_pid;
 
-	threads = thread_map__new(target_pid, target_tid);
-	if (threads == NULL) {
-		pr_err("Problems finding threads of monitor\n");
-		usage_with_options(record_usage, record_options);
-	}
-
-	if (target_tid != -1)
-		cpus = cpu_map__dummy_new();
-	else
-		cpus = cpu_map__new(cpu_list);
-
-	if (cpus == NULL)
+	if (perf_evlist__create_maps(evsel_list, target_pid,
+				     target_tid, cpu_list) < 0)
 		usage_with_options(record_usage, record_options);
 
 	list_for_each_entry(pos, &evsel_list->entries, node) {
-		if (perf_evsel__alloc_fd(pos, cpus->nr, threads->nr) < 0)
+		if (perf_evsel__alloc_fd(pos, evsel_list->cpus->nr,
+					 evsel_list->threads->nr) < 0)
 			goto out_free_fd;
 		if (perf_header__push_event(pos->attr.config, event_name(pos)))
 			goto out_free_fd;
 	}
 
-	if (perf_evlist__alloc_pollfd(evsel_list, cpus->nr, threads->nr) < 0)
+	if (perf_evlist__alloc_pollfd(evsel_list) < 0)
 		goto out_free_fd;
 
 	if (user_interval != ULLONG_MAX)
@@ -893,10 +883,8 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
 	}
 
 	err = __cmd_record(argc, argv);
-
 out_free_fd:
-	thread_map__delete(threads);
-	threads = NULL;
+	perf_evlist__delete_maps(evsel_list);
 out_symbol_exit:
 	symbol__exit();
 	return err;
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 8906adf..e0f9575 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -76,7 +76,6 @@ static struct perf_event_attr default_attrs[] = {
 struct perf_evlist		*evsel_list;
 
 static bool			system_wide			=  false;
-static struct cpu_map		*cpus;
 static int			run_idx				=  0;
 
 static int			run_count			=  1;
@@ -85,7 +84,6 @@ static bool			scale				=  true;
 static bool			no_aggr				= false;
 static pid_t			target_pid			= -1;
 static pid_t			target_tid			= -1;
-static struct thread_map	*threads;
 static pid_t			child_pid			= -1;
 static bool			null_run			=  false;
 static bool			big_num				=  true;
@@ -170,7 +168,7 @@ static int create_perf_stat_counter(struct perf_evsel *evsel)
 				    PERF_FORMAT_TOTAL_TIME_RUNNING;
 
 	if (system_wide)
-		return perf_evsel__open_per_cpu(evsel, cpus, false, false);
+		return perf_evsel__open_per_cpu(evsel, evsel_list->cpus, false, false);
 
 	attr->inherit = !no_inherit;
 	if (target_pid == -1 && target_tid == -1) {
@@ -178,7 +176,7 @@ static int create_perf_stat_counter(struct perf_evsel *evsel)
 		attr->enable_on_exec = 1;
 	}
 
-	return perf_evsel__open_per_thread(evsel, threads, false, false);
+	return perf_evsel__open_per_thread(evsel, evsel_list->threads, false, false);
 }
 
 /*
@@ -203,7 +201,8 @@ static int read_counter_aggr(struct perf_evsel *counter)
 	u64 *count = counter->counts->aggr.values;
 	int i;
 
-	if (__perf_evsel__read(counter, cpus->nr, threads->nr, scale) < 0)
+	if (__perf_evsel__read(counter, evsel_list->cpus->nr,
+			       evsel_list->threads->nr, scale) < 0)
 		return -1;
 
 	for (i = 0; i < 3; i++)
@@ -236,7 +235,7 @@ static int read_counter(struct perf_evsel *counter)
 	u64 *count;
 	int cpu;
 
-	for (cpu = 0; cpu < cpus->nr; cpu++) {
+	for (cpu = 0; cpu < evsel_list->cpus->nr; cpu++) {
 		if (__perf_evsel__read_on_cpu(counter, cpu, 0, scale) < 0)
 			return -1;
 
@@ -301,7 +300,7 @@ static int run_perf_stat(int argc __used, const char **argv)
 		}
 
 		if (target_tid == -1 && target_pid == -1 && !system_wide)
-			threads->map[0] = child_pid;
+			evsel_list->threads->map[0] = child_pid;
 
 		/*
 		 * Wait for the child to be ready to exec.
@@ -353,12 +352,13 @@ static int run_perf_stat(int argc __used, const char **argv)
 	if (no_aggr) {
 		list_for_each_entry(counter, &evsel_list->entries, node) {
 			read_counter(counter);
-			perf_evsel__close_fd(counter, cpus->nr, 1);
+			perf_evsel__close_fd(counter, evsel_list->cpus->nr, 1);
 		}
 	} else {
 		list_for_each_entry(counter, &evsel_list->entries, node) {
 			read_counter_aggr(counter);
-			perf_evsel__close_fd(counter, cpus->nr, threads->nr);
+			perf_evsel__close_fd(counter, evsel_list->cpus->nr,
+					     evsel_list->threads->nr);
 		}
 	}
 
@@ -386,7 +386,7 @@ static void nsec_printout(int cpu, struct perf_evsel *evsel, double avg)
 	if (no_aggr)
 		sprintf(cpustr, "CPU%*d%s",
 			csv_output ? 0 : -4,
-			cpus->map[cpu], csv_sep);
+			evsel_list->cpus->map[cpu], csv_sep);
 
 	fprintf(stderr, fmt, cpustr, msecs, csv_sep, event_name(evsel));
 
@@ -414,7 +414,7 @@ static void abs_printout(int cpu, struct perf_evsel *evsel, double avg)
 	if (no_aggr)
 		sprintf(cpustr, "CPU%*d%s",
 			csv_output ? 0 : -4,
-			cpus->map[cpu], csv_sep);
+			evsel_list->cpus->map[cpu], csv_sep);
 	else
 		cpu = 0;
 
@@ -500,14 +500,14 @@ static void print_counter(struct perf_evsel *counter)
 	u64 ena, run, val;
 	int cpu;
 
-	for (cpu = 0; cpu < cpus->nr; cpu++) {
+	for (cpu = 0; cpu < evsel_list->cpus->nr; cpu++) {
 		val = counter->counts->cpu[cpu].val;
 		ena = counter->counts->cpu[cpu].ena;
 		run = counter->counts->cpu[cpu].run;
 		if (run == 0 || ena == 0) {
 			fprintf(stderr, "CPU%*d%s%*s%s%-24s",
 				csv_output ? 0 : -4,
-				cpus->map[cpu], csv_sep,
+				evsel_list->cpus->map[cpu], csv_sep,
 				csv_output ? 0 : 18,
 				"<not counted>", csv_sep,
 				event_name(counter));
@@ -652,7 +652,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
 
 	setlocale(LC_ALL, "");
 
-	evsel_list = perf_evlist__new();
+	evsel_list = perf_evlist__new(NULL, NULL);
 	if (evsel_list == NULL)
 		return -ENOMEM;
 
@@ -701,18 +701,18 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
 	if (target_pid != -1)
 		target_tid = target_pid;
 
-	threads = thread_map__new(target_pid, target_tid);
-	if (threads == NULL) {
+	evsel_list->threads = thread_map__new(target_pid, target_tid);
+	if (evsel_list->threads == NULL) {
 		pr_err("Problems finding threads of monitor\n");
 		usage_with_options(stat_usage, options);
 	}
 
 	if (system_wide)
-		cpus = cpu_map__new(cpu_list);
+		evsel_list->cpus = cpu_map__new(cpu_list);
 	else
-		cpus = cpu_map__dummy_new();
+		evsel_list->cpus = cpu_map__dummy_new();
 
-	if (cpus == NULL) {
+	if (evsel_list->cpus == NULL) {
 		perror("failed to parse CPUs map");
 		usage_with_options(stat_usage, options);
 		return -1;
@@ -720,8 +720,8 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
 
 	list_for_each_entry(pos, &evsel_list->entries, node) {
 		if (perf_evsel__alloc_stat_priv(pos) < 0 ||
-		    perf_evsel__alloc_counts(pos, cpus->nr) < 0 ||
-		    perf_evsel__alloc_fd(pos, cpus->nr, threads->nr) < 0)
+		    perf_evsel__alloc_counts(pos, evsel_list->cpus->nr) < 0 ||
+		    perf_evsel__alloc_fd(pos, evsel_list->cpus->nr, evsel_list->threads->nr) < 0)
 			goto out_free_fd;
 	}
 
@@ -750,7 +750,6 @@ out_free_fd:
 		perf_evsel__free_stat_priv(pos);
 	perf_evlist__delete(evsel_list);
 out:
-	thread_map__delete(threads);
-	threads = NULL;
+	perf_evlist__delete_maps(evsel_list);
 	return status;
 }
diff --git a/tools/perf/builtin-test.c b/tools/perf/builtin-test.c
index 845b9bd..1b2106c 100644
--- a/tools/perf/builtin-test.c
+++ b/tools/perf/builtin-test.c
@@ -509,7 +509,7 @@ static int test__basic_mmap(void)
 		goto out_free_cpus;
 	}
 
-	evlist = perf_evlist__new();
+	evlist = perf_evlist__new(cpus, threads);
 	if (evlist == NULL) {
 		pr_debug("perf_evlist__new\n");
 		goto out_free_cpus;
@@ -537,7 +537,7 @@ static int test__basic_mmap(void)
 		}
 	}
 
-	if (perf_evlist__mmap(evlist, cpus, threads, 128, true) < 0) {
+	if (perf_evlist__mmap(evlist, 128, true) < 0) {
 		pr_debug("failed to mmap events: %d (%s)\n", errno,
 			 strerror(errno));
 		goto out_close_fd;
@@ -579,7 +579,7 @@ static int test__basic_mmap(void)
 
 	err = 0;
 out_munmap:
-	perf_evlist__munmap(evlist, 1);
+	perf_evlist__munmap(evlist);
 out_close_fd:
 	for (i = 0; i < nsyscalls; ++i)
 		perf_evsel__close_fd(evsels[i], 1, threads->nr);
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 2f4d1f2..599036b 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -73,9 +73,7 @@ static int			print_entries;
 
 static int			target_pid			=     -1;
 static int			target_tid			=     -1;
-static struct thread_map	*threads;
 static bool			inherit				=  false;
-static struct cpu_map		*cpus;
 static int			realtime_prio			=      0;
 static bool			group				=  false;
 static unsigned int		page_size;
@@ -567,12 +565,13 @@ static void print_sym_table(struct perf_session *session)
 		printf(" (all");
 
 	if (cpu_list)
-		printf(", CPU%s: %s)\n", cpus->nr > 1 ? "s" : "", cpu_list);
+		printf(", CPU%s: %s)\n", evsel_list->cpus->nr > 1 ? "s" : "", cpu_list);
 	else {
 		if (target_tid != -1)
 			printf(")\n");
 		else
-			printf(", %d CPU%s)\n", cpus->nr, cpus->nr > 1 ? "s" : "");
+			printf(", %d CPU%s)\n", evsel_list->cpus->nr,
+			       evsel_list->cpus->nr > 1 ? "s" : "");
 	}
 
 	printf("%-*.*s\n", win_width, win_width, graph_dotted_line);
@@ -1124,7 +1123,7 @@ static void perf_session__mmap_read(struct perf_session *self)
 {
 	int i;
 
-	for (i = 0; i < cpus->nr; i++)
+	for (i = 0; i < evsel_list->cpus->nr; i++)
 		perf_session__mmap_read_cpu(self, i);
 }
 
@@ -1150,7 +1149,8 @@ static void start_counters(struct perf_evlist *evlist)
 
 		attr->mmap = 1;
 try_again:
-		if (perf_evsel__open(counter, cpus, threads, group, inherit) < 0) {
+		if (perf_evsel__open(counter, evsel_list->cpus,
+				     evsel_list->threads, group, inherit) < 0) {
 			int err = errno;
 
 			if (err == EPERM || err == EACCES)
@@ -1181,7 +1181,7 @@ try_again:
 		}
 	}
 
-	if (perf_evlist__mmap(evlist, cpus, threads, mmap_pages, false) < 0)
+	if (perf_evlist__mmap(evlist, mmap_pages, false) < 0)
 		die("failed to mmap with %d (%s)\n", errno, strerror(errno));
 }
 
@@ -1296,7 +1296,7 @@ int cmd_top(int argc, const char **argv, const char *prefix __used)
 	struct perf_evsel *pos;
 	int status = -ENOMEM;
 
-	evsel_list = perf_evlist__new();
+	evsel_list = perf_evlist__new(NULL, NULL);
 	if (evsel_list == NULL)
 		return -ENOMEM;
 
@@ -1306,15 +1306,6 @@ int cmd_top(int argc, const char **argv, const char *prefix __used)
 	if (argc)
 		usage_with_options(top_usage, options);
 
-	if (target_pid != -1)
-		target_tid = target_pid;
-
-	threads = thread_map__new(target_pid, target_tid);
-	if (threads == NULL) {
-		pr_err("Problems finding threads of monitor\n");
-		usage_with_options(top_usage, options);
-	}
-
 	/* CPU and PID are mutually exclusive */
 	if (target_tid > 0 && cpu_list) {
 		printf("WARNING: PID switch overriding CPU\n");
@@ -1322,6 +1313,13 @@ int cmd_top(int argc, const char **argv, const char *prefix __used)
 		cpu_list = NULL;
 	}
 
+	if (target_pid != -1)
+		target_tid = target_pid;
+
+	if (perf_evlist__create_maps(evsel_list, target_pid,
+				     target_tid, cpu_list) < 0)
+		usage_with_options(top_usage, options);
+
 	if (!evsel_list->nr_entries &&
 	    perf_evlist__add_default(evsel_list) < 0) {
 		pr_err("Not enough memory for event selector list\n");
@@ -1343,16 +1341,9 @@ int cmd_top(int argc, const char **argv, const char *prefix __used)
 		exit(EXIT_FAILURE);
 	}
 
-	if (target_tid != -1)
-		cpus = cpu_map__dummy_new();
-	else
-		cpus = cpu_map__new(cpu_list);
-
-	if (cpus == NULL)
-		usage_with_options(top_usage, options);
-
 	list_for_each_entry(pos, &evsel_list->entries, node) {
-		if (perf_evsel__alloc_fd(pos, cpus->nr, threads->nr) < 0)
+		if (perf_evsel__alloc_fd(pos, evsel_list->cpus->nr,
+					 evsel_list->threads->nr) < 0)
 			goto out_free_fd;
 		/*
 		 * Fill in the ones not specifically initialized via -c:
@@ -1363,8 +1354,8 @@ int cmd_top(int argc, const char **argv, const char *prefix __used)
 		pos->attr.sample_period = default_interval;
 	}
 
-	if (perf_evlist__alloc_pollfd(evsel_list, cpus->nr, threads->nr) < 0 ||
-	    perf_evlist__alloc_mmap(evsel_list, cpus->nr) < 0)
+	if (perf_evlist__alloc_pollfd(evsel_list) < 0 ||
+	    perf_evlist__alloc_mmap(evsel_list) < 0)
 		goto out_free_fd;
 
 	sym_evsel = list_entry(evsel_list->entries.next, struct perf_evsel, node);
diff --git a/tools/perf/python/twatch.py b/tools/perf/python/twatch.py
index 5e9f3b7..df638c4 100755
--- a/tools/perf/python/twatch.py
+++ b/tools/perf/python/twatch.py
@@ -23,9 +23,9 @@ def main():
 			   sample_id_all = 1,
 			   sample_type = perf.SAMPLE_PERIOD | perf.SAMPLE_TID | perf.SAMPLE_CPU | perf.SAMPLE_TID)
 	evsel.open(cpus = cpus, threads = threads);
-	evlist = perf.evlist()
+	evlist = perf.evlist(cpus, threads)
 	evlist.add(evsel)
-	evlist.mmap(cpus = cpus, threads = threads)
+	evlist.mmap()
 	while True:
 		evlist.poll(timeout = -1)
 		for cpu in cpus:
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index dcd5932..95b21fe 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -21,21 +21,24 @@
 #define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y))
 #define SID(e, x, y) xyarray__entry(e->id, x, y)
 
-void perf_evlist__init(struct perf_evlist *evlist)
+void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus,
+		       struct thread_map *threads)
 {
 	int i;
 
 	for (i = 0; i < PERF_EVLIST__HLIST_SIZE; ++i)
 		INIT_HLIST_HEAD(&evlist->heads[i]);
 	INIT_LIST_HEAD(&evlist->entries);
+	perf_evlist__set_maps(evlist, cpus, threads);
 }
 
-struct perf_evlist *perf_evlist__new(void)
+struct perf_evlist *perf_evlist__new(struct cpu_map *cpus,
+				     struct thread_map *threads)
 {
 	struct perf_evlist *evlist = zalloc(sizeof(*evlist));
 
 	if (evlist != NULL)
-		perf_evlist__init(evlist);
+		perf_evlist__init(evlist, cpus, threads);
 
 	return evlist;
 }
@@ -88,9 +91,9 @@ int perf_evlist__add_default(struct perf_evlist *evlist)
 	return 0;
 }
 
-int perf_evlist__alloc_pollfd(struct perf_evlist *evlist, int ncpus, int nthreads)
+int perf_evlist__alloc_pollfd(struct perf_evlist *evlist)
 {
-	int nfds = ncpus * nthreads * evlist->nr_entries;
+	int nfds = evlist->cpus->nr * evlist->threads->nr * evlist->nr_entries;
 	evlist->pollfd = malloc(sizeof(struct pollfd) * nfds);
 	return evlist->pollfd != NULL ? 0 : -ENOMEM;
 }
@@ -213,11 +216,11 @@ union perf_event *perf_evlist__read_on_cpu(struct perf_evlist *evlist, int cpu)
 	return event;
 }
 
-void perf_evlist__munmap(struct perf_evlist *evlist, int ncpus)
+void perf_evlist__munmap(struct perf_evlist *evlist)
 {
 	int cpu;
 
-	for (cpu = 0; cpu < ncpus; cpu++) {
+	for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
 		if (evlist->mmap[cpu].base != NULL) {
 			munmap(evlist->mmap[cpu].base, evlist->mmap_len);
 			evlist->mmap[cpu].base = NULL;
@@ -225,9 +228,9 @@ void perf_evlist__munmap(struct perf_evlist *evlist, int ncpus)
 	}
 }
 
-int perf_evlist__alloc_mmap(struct perf_evlist *evlist, int ncpus)
+int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
 {
-	evlist->mmap = zalloc(ncpus * sizeof(struct perf_mmap));
+	evlist->mmap = zalloc(evlist->cpus->nr * sizeof(struct perf_mmap));
 	return evlist->mmap != NULL ? 0 : -ENOMEM;
 }
 
@@ -248,8 +251,6 @@ static int __perf_evlist__mmap(struct perf_evlist *evlist, int cpu, int prot,
 /** perf_evlist__mmap - Create per cpu maps to receive events
  *
  * @evlist - list of events
- * @cpus - cpu map being monitored
- * @threads - threads map being monitored
  * @pages - map length in pages
  * @overwrite - overwrite older events?
  *
@@ -259,21 +260,22 @@ static int __perf_evlist__mmap(struct perf_evlist *evlist, int cpu, int prot,
  *	unsigned int head = perf_mmap__read_head(m);
  *
  *	perf_mmap__write_tail(m, head)
+ *
+ * Using perf_evlist__read_on_cpu does this automatically.
  */
-int perf_evlist__mmap(struct perf_evlist *evlist, struct cpu_map *cpus,
-		      struct thread_map *threads, int pages, bool overwrite)
+int perf_evlist__mmap(struct perf_evlist *evlist, int pages, bool overwrite)
 {
 	unsigned int page_size = sysconf(_SC_PAGE_SIZE);
 	int mask = pages * page_size - 1, cpu;
 	struct perf_evsel *first_evsel, *evsel;
+	const struct cpu_map *cpus = evlist->cpus;
+	const struct thread_map *threads = evlist->threads;
 	int thread, prot = PROT_READ | (overwrite ? 0 : PROT_WRITE);
 
-	if (evlist->mmap == NULL &&
-	    perf_evlist__alloc_mmap(evlist, cpus->nr) < 0)
+	if (evlist->mmap == NULL && perf_evlist__alloc_mmap(evlist) < 0)
 		return -ENOMEM;
 
-	if (evlist->pollfd == NULL &&
-	    perf_evlist__alloc_pollfd(evlist, cpus->nr, threads->nr) < 0)
+	if (evlist->pollfd == NULL && perf_evlist__alloc_pollfd(evlist) < 0)
 		return -ENOMEM;
 
 	evlist->overwrite = overwrite;
@@ -315,3 +317,34 @@ out_unmap:
 	}
 	return -1;
 }
+
+int perf_evlist__create_maps(struct perf_evlist *evlist, pid_t target_pid,
+			     pid_t target_tid, const char *cpu_list)
+{
+	evlist->threads = thread_map__new(target_pid, target_tid);
+
+	if (evlist->threads == NULL)
+		return -1;
+
+	if (target_tid != -1)
+		evlist->cpus = cpu_map__dummy_new();
+	else
+		evlist->cpus = cpu_map__new(cpu_list);
+
+	if (evlist->cpus == NULL)
+		goto out_delete_threads;
+
+	return 0;
+
+out_delete_threads:
+	thread_map__delete(evlist->threads);
+	return -1;
+}
+
+void perf_evlist__delete_maps(struct perf_evlist *evlist)
+{
+	cpu_map__delete(evlist->cpus);
+	thread_map__delete(evlist->threads);
+	evlist->cpus	= NULL;
+	evlist->threads = NULL;
+}
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 85aca6e..c988405 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -22,28 +22,43 @@ struct perf_evlist {
 	union perf_event event_copy;
 	struct perf_mmap *mmap;
 	struct pollfd	 *pollfd;
+	struct thread_map *threads;
+	struct cpu_map	  *cpus;
 };
 
 struct perf_evsel;
 
-struct perf_evlist *perf_evlist__new(void);
-void perf_evlist__init(struct perf_evlist *evlist);
+struct perf_evlist *perf_evlist__new(struct cpu_map *cpus,
+				     struct thread_map *threads);
+void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus,
+		       struct thread_map *threads);
 void perf_evlist__exit(struct perf_evlist *evlist);
 void perf_evlist__delete(struct perf_evlist *evlist);
 
 void perf_evlist__add(struct perf_evlist *evlist, struct perf_evsel *entry);
 int perf_evlist__add_default(struct perf_evlist *evlist);
 
-int perf_evlist__alloc_pollfd(struct perf_evlist *evlist, int ncpus, int nthreads);
+int perf_evlist__alloc_pollfd(struct perf_evlist *evlist);
 void perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd);
 
 struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id);
 
 union perf_event *perf_evlist__read_on_cpu(struct perf_evlist *self, int cpu);
 
-int perf_evlist__alloc_mmap(struct perf_evlist *evlist, int ncpus);
-int perf_evlist__mmap(struct perf_evlist *evlist, struct cpu_map *cpus,
-		      struct thread_map *threads, int pages, bool overwrite);
-void perf_evlist__munmap(struct perf_evlist *evlist, int ncpus);
+int perf_evlist__alloc_mmap(struct perf_evlist *evlist);
+int perf_evlist__mmap(struct perf_evlist *evlist, int pages, bool overwrite);
+void perf_evlist__munmap(struct perf_evlist *evlist);
+
+static inline void perf_evlist__set_maps(struct perf_evlist *evlist,
+					 struct cpu_map *cpus,
+					 struct thread_map *threads)
+{
+	evlist->cpus	= cpus;
+	evlist->threads	= threads;
+}
+
+int perf_evlist__create_maps(struct perf_evlist *evlist, pid_t target_pid,
+			     pid_t target_tid, const char *cpu_list);
+void perf_evlist__delete_maps(struct perf_evlist *evlist);
 
 #endif /* __PERF_EVLIST_H */
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index 88d4789..d2d5217 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -553,7 +553,16 @@ struct pyrf_evlist {
 static int pyrf_evlist__init(struct pyrf_evlist *pevlist,
 			     PyObject *args, PyObject *kwargs)
 {
-	perf_evlist__init(&pevlist->evlist);
+	PyObject *pcpus = NULL, *pthreads = NULL;
+	struct cpu_map *cpus;
+	struct thread_map *threads;
+
+	if (!PyArg_ParseTuple(args, "OO", &pcpus, &pthreads))
+		return -1;
+
+	threads = ((struct pyrf_thread_map *)pthreads)->threads;
+	cpus = ((struct pyrf_cpu_map *)pcpus)->cpus;
+	perf_evlist__init(&pevlist->evlist, cpus, threads);
 	return 0;
 }
 
@@ -567,21 +576,15 @@ static PyObject *pyrf_evlist__mmap(struct pyrf_evlist *pevlist,
 				   PyObject *args, PyObject *kwargs)
 {
 	struct perf_evlist *evlist = &pevlist->evlist;
-	PyObject *pcpus = NULL, *pthreads = NULL;
-	struct cpu_map *cpus = NULL;
-	struct thread_map *threads = NULL;
-	static char *kwlist[] = {"cpus", "threads", "pages", "overwrite",
+	static char *kwlist[] = {"pages", "overwrite",
 				  NULL, NULL};
 	int pages = 128, overwrite = false;
 
-	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "OO|ii", kwlist,
-					 &pcpus, &pthreads, &pages, &overwrite))
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|ii", kwlist,
+					 &pages, &overwrite))
 		return NULL;
 
-	threads = ((struct pyrf_thread_map *)pthreads)->threads;
-	cpus = ((struct pyrf_cpu_map *)pcpus)->cpus;
-
-	if (perf_evlist__mmap(evlist, cpus, threads, pages, overwrite) < 0) {
+	if (perf_evlist__mmap(evlist, pages, overwrite) < 0) {
 		PyErr_SetFromErrno(PyExc_OSError);
 		return NULL;
 	}