Initial import

1 files changed, 1570 insertions, 0 deletions

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
new file mode 100644
index 000000000..080be93ee
--- /dev/null
+++ b/tools/perf/util/evlist.c
@@ -0,0 +1,1570 @@
+/*
+ * Copyright (C) 2011, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
+ *
+ * Parts came from builtin-{top,stat,record}.c, see those files for further
+ * copyright notes.
+ *
+ * Released under the GPL v2. (and only v2, not any later version)
+ */
+#include "util.h"
+#include <api/fs/fs.h>
+#include <poll.h>
+#include "cpumap.h"
+#include "thread_map.h"
+#include "target.h"
+#include "evlist.h"
+#include "evsel.h"
+#include "debug.h"
+#include <unistd.h>
+
+#include "parse-events.h"
+#include "parse-options.h"
+
+#include <sys/mman.h>
+
+#include <linux/bitops.h>
+#include <linux/hash.h>
+#include <linux/log2.h>
+
+static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx);
+static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx);
+
+#define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y))
+#define SID(e, x, y) xyarray__entry(e->sample_id, x, y)
+
+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);
+	fdarray__init(&evlist->pollfd, 64);
+	evlist->workload.pid = -1;
+}
+
+struct perf_evlist *perf_evlist__new(void)
+{
+	struct perf_evlist *evlist = zalloc(sizeof(*evlist));
+
+	if (evlist != NULL)
+		perf_evlist__init(evlist, NULL, NULL);
+
+	return evlist;
+}
+
+struct perf_evlist *perf_evlist__new_default(void)
+{
+	struct perf_evlist *evlist = perf_evlist__new();
+
+	if (evlist && perf_evlist__add_default(evlist)) {
+		perf_evlist__delete(evlist);
+		evlist = NULL;
+	}
+
+	return evlist;
+}
+
+/**
+ * perf_evlist__set_id_pos - set the positions of event ids.
+ * @evlist: selected event list
+ *
+ * Events with compatible sample types all have the same id_pos
+ * and is_pos.  For convenience, put a copy on evlist.
+ */
+void perf_evlist__set_id_pos(struct perf_evlist *evlist)
+{
+	struct perf_evsel *first = perf_evlist__first(evlist);
+
+	evlist->id_pos = first->id_pos;
+	evlist->is_pos = first->is_pos;
+}
+
+static void perf_evlist__update_id_pos(struct perf_evlist *evlist)
+{
+	struct perf_evsel *evsel;
+
+	evlist__for_each(evlist, evsel)
+		perf_evsel__calc_id_pos(evsel);
+
+	perf_evlist__set_id_pos(evlist);
+}
+
+static void perf_evlist__purge(struct perf_evlist *evlist)
+{
+	struct perf_evsel *pos, *n;
+
+	evlist__for_each_safe(evlist, n, pos) {
+		list_del_init(&pos->node);
+		perf_evsel__delete(pos);
+	}
+
+	evlist->nr_entries = 0;
+}
+
+void perf_evlist__exit(struct perf_evlist *evlist)
+{
+	zfree(&evlist->mmap);
+	fdarray__exit(&evlist->pollfd);
+}
+
+void perf_evlist__delete(struct perf_evlist *evlist)
+{
+	perf_evlist__munmap(evlist);
+	perf_evlist__close(evlist);
+	cpu_map__delete(evlist->cpus);
+	thread_map__delete(evlist->threads);
+	evlist->cpus = NULL;
+	evlist->threads = NULL;
+	perf_evlist__purge(evlist);
+	perf_evlist__exit(evlist);
+	free(evlist);
+}
+
+void perf_evlist__add(struct perf_evlist *evlist, struct perf_evsel *entry)
+{
+	list_add_tail(&entry->node, &evlist->entries);
+	entry->idx = evlist->nr_entries;
+	entry->tracking = !entry->idx;
+
+	if (!evlist->nr_entries++)
+		perf_evlist__set_id_pos(evlist);
+}
+
+void perf_evlist__splice_list_tail(struct perf_evlist *evlist,
+				   struct list_head *list,
+				   int nr_entries)
+{
+	bool set_id_pos = !evlist->nr_entries;
+
+	list_splice_tail(list, &evlist->entries);
+	evlist->nr_entries += nr_entries;
+	if (set_id_pos)
+		perf_evlist__set_id_pos(evlist);
+}
+
+void __perf_evlist__set_leader(struct list_head *list)
+{
+	struct perf_evsel *evsel, *leader;
+
+	leader = list_entry(list->next, struct perf_evsel, node);
+	evsel = list_entry(list->prev, struct perf_evsel, node);
+
+	leader->nr_members = evsel->idx - leader->idx + 1;
+
+	__evlist__for_each(list, evsel) {
+		evsel->leader = leader;
+	}
+}
+
+void perf_evlist__set_leader(struct perf_evlist *evlist)
+{
+	if (evlist->nr_entries) {
+		evlist->nr_groups = evlist->nr_entries > 1 ? 1 : 0;
+		__perf_evlist__set_leader(&evlist->entries);
+	}
+}
+
+int perf_evlist__add_default(struct perf_evlist *evlist)
+{
+	struct perf_event_attr attr = {
+		.type = PERF_TYPE_HARDWARE,
+		.config = PERF_COUNT_HW_CPU_CYCLES,
+	};
+	struct perf_evsel *evsel;
+
+	event_attr_init(&attr);
+
+	evsel = perf_evsel__new(&attr);
+	if (evsel == NULL)
+		goto error;
+
+	/* use strdup() because free(evsel) assumes name is allocated */
+	evsel->name = strdup("cycles");
+	if (!evsel->name)
+		goto error_free;
+
+	perf_evlist__add(evlist, evsel);
+	return 0;
+error_free:
+	perf_evsel__delete(evsel);
+error:
+	return -ENOMEM;
+}
+
+static int perf_evlist__add_attrs(struct perf_evlist *evlist,
+				  struct perf_event_attr *attrs, size_t nr_attrs)
+{
+	struct perf_evsel *evsel, *n;
+	LIST_HEAD(head);
+	size_t i;
+
+	for (i = 0; i < nr_attrs; i++) {
+		evsel = perf_evsel__new_idx(attrs + i, evlist->nr_entries + i);
+		if (evsel == NULL)
+			goto out_delete_partial_list;
+		list_add_tail(&evsel->node, &head);
+	}
+
+	perf_evlist__splice_list_tail(evlist, &head, nr_attrs);
+
+	return 0;
+
+out_delete_partial_list:
+	__evlist__for_each_safe(&head, n, evsel)
+		perf_evsel__delete(evsel);
+	return -1;
+}
+
+int __perf_evlist__add_default_attrs(struct perf_evlist *evlist,
+				     struct perf_event_attr *attrs, size_t nr_attrs)
+{
+	size_t i;
+
+	for (i = 0; i < nr_attrs; i++)
+		event_attr_init(attrs + i);
+
+	return perf_evlist__add_attrs(evlist, attrs, nr_attrs);
+}
+
+struct perf_evsel *
+perf_evlist__find_tracepoint_by_id(struct perf_evlist *evlist, int id)
+{
+	struct perf_evsel *evsel;
+
+	evlist__for_each(evlist, evsel) {
+		if (evsel->attr.type   == PERF_TYPE_TRACEPOINT &&
+		    (int)evsel->attr.config == id)
+			return evsel;
+	}
+
+	return NULL;
+}
+
+struct perf_evsel *
+perf_evlist__find_tracepoint_by_name(struct perf_evlist *evlist,
+				     const char *name)
+{
+	struct perf_evsel *evsel;
+
+	evlist__for_each(evlist, evsel) {
+		if ((evsel->attr.type == PERF_TYPE_TRACEPOINT) &&
+		    (strcmp(evsel->name, name) == 0))
+			return evsel;
+	}
+
+	return NULL;
+}
+
+int perf_evlist__add_newtp(struct perf_evlist *evlist,
+			   const char *sys, const char *name, void *handler)
+{
+	struct perf_evsel *evsel = perf_evsel__newtp(sys, name);
+
+	if (evsel == NULL)
+		return -1;
+
+	evsel->handler = handler;
+	perf_evlist__add(evlist, evsel);
+	return 0;
+}
+
+static int perf_evlist__nr_threads(struct perf_evlist *evlist,
+				   struct perf_evsel *evsel)
+{
+	if (evsel->system_wide)
+		return 1;
+	else
+		return thread_map__nr(evlist->threads);
+}
+
+void perf_evlist__disable(struct perf_evlist *evlist)
+{
+	int cpu, thread;
+	struct perf_evsel *pos;
+	int nr_cpus = cpu_map__nr(evlist->cpus);
+	int nr_threads;
+
+	for (cpu = 0; cpu < nr_cpus; cpu++) {
+		evlist__for_each(evlist, pos) {
+			if (!perf_evsel__is_group_leader(pos) || !pos->fd)
+				continue;
+			nr_threads = perf_evlist__nr_threads(evlist, pos);
+			for (thread = 0; thread < nr_threads; thread++)
+				ioctl(FD(pos, cpu, thread),
+				      PERF_EVENT_IOC_DISABLE, 0);
+		}
+	}
+}
+
+void perf_evlist__enable(struct perf_evlist *evlist)
+{
+	int cpu, thread;
+	struct perf_evsel *pos;
+	int nr_cpus = cpu_map__nr(evlist->cpus);
+	int nr_threads;
+
+	for (cpu = 0; cpu < nr_cpus; cpu++) {
+		evlist__for_each(evlist, pos) {
+			if (!perf_evsel__is_group_leader(pos) || !pos->fd)
+				continue;
+			nr_threads = perf_evlist__nr_threads(evlist, pos);
+			for (thread = 0; thread < nr_threads; thread++)
+				ioctl(FD(pos, cpu, thread),
+				      PERF_EVENT_IOC_ENABLE, 0);
+		}
+	}
+}
+
+int perf_evlist__disable_event(struct perf_evlist *evlist,
+			       struct perf_evsel *evsel)
+{
+	int cpu, thread, err;
+	int nr_cpus = cpu_map__nr(evlist->cpus);
+	int nr_threads = perf_evlist__nr_threads(evlist, evsel);
+
+	if (!evsel->fd)
+		return 0;
+
+	for (cpu = 0; cpu < nr_cpus; cpu++) {
+		for (thread = 0; thread < nr_threads; thread++) {
+			err = ioctl(FD(evsel, cpu, thread),
+				    PERF_EVENT_IOC_DISABLE, 0);
+			if (err)
+				return err;
+		}
+	}
+	return 0;
+}
+
+int perf_evlist__enable_event(struct perf_evlist *evlist,
+			      struct perf_evsel *evsel)
+{
+	int cpu, thread, err;
+	int nr_cpus = cpu_map__nr(evlist->cpus);
+	int nr_threads = perf_evlist__nr_threads(evlist, evsel);
+
+	if (!evsel->fd)
+		return -EINVAL;
+
+	for (cpu = 0; cpu < nr_cpus; cpu++) {
+		for (thread = 0; thread < nr_threads; thread++) {
+			err = ioctl(FD(evsel, cpu, thread),
+				    PERF_EVENT_IOC_ENABLE, 0);
+			if (err)
+				return err;
+		}
+	}
+	return 0;
+}
+
+static int perf_evlist__enable_event_cpu(struct perf_evlist *evlist,
+					 struct perf_evsel *evsel, int cpu)
+{
+	int thread, err;
+	int nr_threads = perf_evlist__nr_threads(evlist, evsel);
+
+	if (!evsel->fd)
+		return -EINVAL;
+
+	for (thread = 0; thread < nr_threads; thread++) {
+		err = ioctl(FD(evsel, cpu, thread),
+			    PERF_EVENT_IOC_ENABLE, 0);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int perf_evlist__enable_event_thread(struct perf_evlist *evlist,
+					    struct perf_evsel *evsel,
+					    int thread)
+{
+	int cpu, err;
+	int nr_cpus = cpu_map__nr(evlist->cpus);
+
+	if (!evsel->fd)
+		return -EINVAL;
+
+	for (cpu = 0; cpu < nr_cpus; cpu++) {
+		err = ioctl(FD(evsel, cpu, thread), PERF_EVENT_IOC_ENABLE, 0);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+int perf_evlist__enable_event_idx(struct perf_evlist *evlist,
+				  struct perf_evsel *evsel, int idx)
+{
+	bool per_cpu_mmaps = !cpu_map__empty(evlist->cpus);
+
+	if (per_cpu_mmaps)
+		return perf_evlist__enable_event_cpu(evlist, evsel, idx);
+	else
+		return perf_evlist__enable_event_thread(evlist, evsel, idx);
+}
+
+int perf_evlist__alloc_pollfd(struct perf_evlist *evlist)
+{
+	int nr_cpus = cpu_map__nr(evlist->cpus);
+	int nr_threads = thread_map__nr(evlist->threads);
+	int nfds = 0;
+	struct perf_evsel *evsel;
+
+	evlist__for_each(evlist, evsel) {
+		if (evsel->system_wide)
+			nfds += nr_cpus;
+		else
+			nfds += nr_cpus * nr_threads;
+	}
+
+	if (fdarray__available_entries(&evlist->pollfd) < nfds &&
+	    fdarray__grow(&evlist->pollfd, nfds) < 0)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int __perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd, int idx)
+{
+	int pos = fdarray__add(&evlist->pollfd, fd, POLLIN | POLLERR | POLLHUP);
+	/*
+	 * Save the idx so that when we filter out fds POLLHUP'ed we can
+	 * close the associated evlist->mmap[] entry.
+	 */
+	if (pos >= 0) {
+		evlist->pollfd.priv[pos].idx = idx;
+
+		fcntl(fd, F_SETFL, O_NONBLOCK);
+	}
+
+	return pos;
+}
+
+int perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd)
+{
+	return __perf_evlist__add_pollfd(evlist, fd, -1);
+}
+
+static void perf_evlist__munmap_filtered(struct fdarray *fda, int fd)
+{
+	struct perf_evlist *evlist = container_of(fda, struct perf_evlist, pollfd);
+
+	perf_evlist__mmap_put(evlist, fda->priv[fd].idx);
+}
+
+int perf_evlist__filter_pollfd(struct perf_evlist *evlist, short revents_and_mask)
+{
+	return fdarray__filter(&evlist->pollfd, revents_and_mask,
+			       perf_evlist__munmap_filtered);
+}
+
+int perf_evlist__poll(struct perf_evlist *evlist, int timeout)
+{
+	return fdarray__poll(&evlist->pollfd, timeout);
+}
+
+static void perf_evlist__id_hash(struct perf_evlist *evlist,
+				 struct perf_evsel *evsel,
+				 int cpu, int thread, u64 id)
+{
+	int hash;
+	struct perf_sample_id *sid = SID(evsel, cpu, thread);
+
+	sid->id = id;
+	sid->evsel = evsel;
+	hash = hash_64(sid->id, PERF_EVLIST__HLIST_BITS);
+	hlist_add_head(&sid->node, &evlist->heads[hash]);
+}
+
+void perf_evlist__id_add(struct perf_evlist *evlist, struct perf_evsel *evsel,
+			 int cpu, int thread, u64 id)
+{
+	perf_evlist__id_hash(evlist, evsel, cpu, thread, id);
+	evsel->id[evsel->ids++] = id;
+}
+
+static int perf_evlist__id_add_fd(struct perf_evlist *evlist,
+				  struct perf_evsel *evsel,
+				  int cpu, int thread, int fd)
+{
+	u64 read_data[4] = { 0, };
+	int id_idx = 1; /* The first entry is the counter value */
+	u64 id;
+	int ret;
+
+	ret = ioctl(fd, PERF_EVENT_IOC_ID, &id);
+	if (!ret)
+		goto add;
+
+	if (errno != ENOTTY)
+		return -1;
+
+	/* Legacy way to get event id.. All hail to old kernels! */
+
+	/*
+	 * This way does not work with group format read, so bail
+	 * out in that case.
+	 */
+	if (perf_evlist__read_format(evlist) & PERF_FORMAT_GROUP)
+		return -1;
+
+	if (!(evsel->attr.read_format & PERF_FORMAT_ID) ||
+	    read(fd, &read_data, sizeof(read_data)) == -1)
+		return -1;
+
+	if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+		++id_idx;
+	if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+		++id_idx;
+
+	id = read_data[id_idx];
+
+ add:
+	perf_evlist__id_add(evlist, evsel, cpu, thread, id);
+	return 0;
+}
+
+static void perf_evlist__set_sid_idx(struct perf_evlist *evlist,
+				     struct perf_evsel *evsel, int idx, int cpu,
+				     int thread)
+{
+	struct perf_sample_id *sid = SID(evsel, cpu, thread);
+	sid->idx = idx;
+	if (evlist->cpus && cpu >= 0)
+		sid->cpu = evlist->cpus->map[cpu];
+	else
+		sid->cpu = -1;
+	if (!evsel->system_wide && evlist->threads && thread >= 0)
+		sid->tid = evlist->threads->map[thread];
+	else
+		sid->tid = -1;
+}
+
+struct perf_sample_id *perf_evlist__id2sid(struct perf_evlist *evlist, u64 id)
+{
+	struct hlist_head *head;
+	struct perf_sample_id *sid;
+	int hash;
+
+	hash = hash_64(id, PERF_EVLIST__HLIST_BITS);
+	head = &evlist->heads[hash];
+
+	hlist_for_each_entry(sid, head, node)
+		if (sid->id == id)
+			return sid;
+
+	return NULL;
+}
+
+struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id)
+{
+	struct perf_sample_id *sid;
+
+	if (evlist->nr_entries == 1)
+		return perf_evlist__first(evlist);
+
+	sid = perf_evlist__id2sid(evlist, id);
+	if (sid)
+		return sid->evsel;
+
+	if (!perf_evlist__sample_id_all(evlist))
+		return perf_evlist__first(evlist);
+
+	return NULL;
+}
+
+static int perf_evlist__event2id(struct perf_evlist *evlist,
+				 union perf_event *event, u64 *id)
+{
+	const u64 *array = event->sample.array;
+	ssize_t n;
+
+	n = (event->header.size - sizeof(event->header)) >> 3;
+
+	if (event->header.type == PERF_RECORD_SAMPLE) {
+		if (evlist->id_pos >= n)
+			return -1;
+		*id = array[evlist->id_pos];
+	} else {
+		if (evlist->is_pos > n)
+			return -1;
+		n -= evlist->is_pos;
+		*id = array[n];
+	}
+	return 0;
+}
+
+static struct perf_evsel *perf_evlist__event2evsel(struct perf_evlist *evlist,
+						   union perf_event *event)
+{
+	struct perf_evsel *first = perf_evlist__first(evlist);
+	struct hlist_head *head;
+	struct perf_sample_id *sid;
+	int hash;
+	u64 id;
+
+	if (evlist->nr_entries == 1)
+		return first;
+
+	if (!first->attr.sample_id_all &&
+	    event->header.type != PERF_RECORD_SAMPLE)
+		return first;
+
+	if (perf_evlist__event2id(evlist, event, &id))
+		return NULL;
+
+	/* Synthesized events have an id of zero */
+	if (!id)
+		return first;
+
+	hash = hash_64(id, PERF_EVLIST__HLIST_BITS);
+	head = &evlist->heads[hash];
+
+	hlist_for_each_entry(sid, head, node) {
+		if (sid->id == id)
+			return sid->evsel;
+	}
+	return NULL;
+}
+
+union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
+{
+	struct perf_mmap *md = &evlist->mmap[idx];
+	u64 head = perf_mmap__read_head(md);
+	u64 old = md->prev;
+	unsigned char *data = md->base + page_size;
+	union perf_event *event = NULL;
+
+	if (evlist->overwrite) {
+		/*
+		 * If we're further behind than half the buffer, there's a chance
+		 * the writer will bite our tail and mess up the samples under us.
+		 *
+		 * If we somehow ended up ahead of the head, we got messed up.
+		 *
+		 * In either case, truncate and restart at head.
+		 */
+		int diff = head - old;
+		if (diff > md->mask / 2 || diff < 0) {
+			fprintf(stderr, "WARNING: failed to keep up with mmap data.\n");
+
+			/*
+			 * head points to a known good entry, start there.
+			 */
+			old = head;
+		}
+	}
+
+	if (old != head) {
+		size_t size;
+
+		event = (union perf_event *)&data[old & md->mask];
+		size = event->header.size;
+
+		/*
+		 * Event straddles the mmap boundary -- header should always
+		 * be inside due to u64 alignment of output.
+		 */
+		if ((old & md->mask) + size != ((old + size) & md->mask)) {
+			unsigned int offset = old;
+			unsigned int len = min(sizeof(*event), size), cpy;
+			void *dst = md->event_copy;
+
+			do {
+				cpy = min(md->mask + 1 - (offset & md->mask), len);
+				memcpy(dst, &data[offset & md->mask], cpy);
+				offset += cpy;
+				dst += cpy;
+				len -= cpy;
+			} while (len);
+
+			event = (union perf_event *) md->event_copy;
+		}
+
+		old += size;
+	}
+
+	md->prev = old;
+
+	return event;
+}
+
+static bool perf_mmap__empty(struct perf_mmap *md)
+{
+	return perf_mmap__read_head(md) == md->prev;
+}
+
+static void perf_evlist__mmap_get(struct perf_evlist *evlist, int idx)
+{
+	++evlist->mmap[idx].refcnt;
+}
+
+static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx)
+{
+	BUG_ON(evlist->mmap[idx].refcnt == 0);
+
+	if (--evlist->mmap[idx].refcnt == 0)
+		__perf_evlist__munmap(evlist, idx);
+}
+
+void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
+{
+	struct perf_mmap *md = &evlist->mmap[idx];
+
+	if (!evlist->overwrite) {
+		u64 old = md->prev;
+
+		perf_mmap__write_tail(md, old);
+	}
+
+	if (md->refcnt == 1 && perf_mmap__empty(md))
+		perf_evlist__mmap_put(evlist, idx);
+}
+
+static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx)
+{
+	if (evlist->mmap[idx].base != NULL) {
+		munmap(evlist->mmap[idx].base, evlist->mmap_len);
+		evlist->mmap[idx].base = NULL;
+		evlist->mmap[idx].refcnt = 0;
+	}
+}
+
+void perf_evlist__munmap(struct perf_evlist *evlist)
+{
+	int i;
+
+	if (evlist->mmap == NULL)
+		return;
+
+	for (i = 0; i < evlist->nr_mmaps; i++)
+		__perf_evlist__munmap(evlist, i);
+
+	zfree(&evlist->mmap);
+}
+
+static int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
+{
+	evlist->nr_mmaps = cpu_map__nr(evlist->cpus);
+	if (cpu_map__empty(evlist->cpus))
+		evlist->nr_mmaps = thread_map__nr(evlist->threads);
+	evlist->mmap = zalloc(evlist->nr_mmaps * sizeof(struct perf_mmap));
+	return evlist->mmap != NULL ? 0 : -ENOMEM;
+}
+
+struct mmap_params {
+	int prot;
+	int mask;
+};
+
+static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
+			       struct mmap_params *mp, int fd)
+{
+	/*
+	 * The last one will be done at perf_evlist__mmap_consume(), so that we
+	 * make sure we don't prevent tools from consuming every last event in
+	 * the ring buffer.
+	 *
+	 * I.e. we can get the POLLHUP meaning that the fd doesn't exist
+	 * anymore, but the last events for it are still in the ring buffer,
+	 * waiting to be consumed.
+	 *
+	 * Tools can chose to ignore this at their own discretion, but the
+	 * evlist layer can't just drop it when filtering events in
+	 * perf_evlist__filter_pollfd().
+	 */
+	evlist->mmap[idx].refcnt = 2;
+	evlist->mmap[idx].prev = 0;
+	evlist->mmap[idx].mask = mp->mask;
+	evlist->mmap[idx].base = mmap(NULL, evlist->mmap_len, mp->prot,
+				      MAP_SHARED, fd, 0);
+	if (evlist->mmap[idx].base == MAP_FAILED) {
+		pr_debug2("failed to mmap perf event ring buffer, error %d\n",
+			  errno);
+		evlist->mmap[idx].base = NULL;
+		return -1;
+	}
+
+	return 0;
+}
+
+static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
+				       struct mmap_params *mp, int cpu,
+				       int thread, int *output)
+{
+	struct perf_evsel *evsel;
+
+	evlist__for_each(evlist, evsel) {
+		int fd;
+
+		if (evsel->system_wide && thread)
+			continue;
+
+		fd = FD(evsel, cpu, thread);
+
+		if (*output == -1) {
+			*output = fd;
+			if (__perf_evlist__mmap(evlist, idx, mp, *output) < 0)
+				return -1;
+		} else {
+			if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, *output) != 0)
+				return -1;
+
+			perf_evlist__mmap_get(evlist, idx);
+		}
+
+		/*
+		 * The system_wide flag causes a selected event to be opened
+		 * always without a pid.  Consequently it will never get a
+		 * POLLHUP, but it is used for tracking in combination with
+		 * other events, so it should not need to be polled anyway.
+		 * Therefore don't add it for polling.
+		 */
+		if (!evsel->system_wide &&
+		    __perf_evlist__add_pollfd(evlist, fd, idx) < 0) {
+			perf_evlist__mmap_put(evlist, idx);
+			return -1;
+		}
+
+		if (evsel->attr.read_format & PERF_FORMAT_ID) {
+			if (perf_evlist__id_add_fd(evlist, evsel, cpu, thread,
+						   fd) < 0)
+				return -1;
+			perf_evlist__set_sid_idx(evlist, evsel, idx, cpu,
+						 thread);
+		}
+	}
+
+	return 0;
+}
+
+static int perf_evlist__mmap_per_cpu(struct perf_evlist *evlist,
+				     struct mmap_params *mp)
+{
+	int cpu, thread;
+	int nr_cpus = cpu_map__nr(evlist->cpus);
+	int nr_threads = thread_map__nr(evlist->threads);
+
+	pr_debug2("perf event ring buffer mmapped per cpu\n");
+	for (cpu = 0; cpu < nr_cpus; cpu++) {
+		int output = -1;
+
+		for (thread = 0; thread < nr_threads; thread++) {
+			if (perf_evlist__mmap_per_evsel(evlist, cpu, mp, cpu,
+							thread, &output))
+				goto out_unmap;
+		}
+	}
+
+	return 0;
+
+out_unmap:
+	for (cpu = 0; cpu < nr_cpus; cpu++)
+		__perf_evlist__munmap(evlist, cpu);
+	return -1;
+}
+
+static int perf_evlist__mmap_per_thread(struct perf_evlist *evlist,
+					struct mmap_params *mp)
+{
+	int thread;
+	int nr_threads = thread_map__nr(evlist->threads);
+
+	pr_debug2("perf event ring buffer mmapped per thread\n");
+	for (thread = 0; thread < nr_threads; thread++) {
+		int output = -1;
+
+		if (perf_evlist__mmap_per_evsel(evlist, thread, mp, 0, thread,
+						&output))
+			goto out_unmap;
+	}
+
+	return 0;
+
+out_unmap:
+	for (thread = 0; thread < nr_threads; thread++)
+		__perf_evlist__munmap(evlist, thread);
+	return -1;
+}
+
+static size_t perf_evlist__mmap_size(unsigned long pages)
+{
+	if (pages == UINT_MAX) {
+		int max;
+
+		if (sysctl__read_int("kernel/perf_event_mlock_kb", &max) < 0) {
+			/*
+			 * Pick a once upon a time good value, i.e. things look
+			 * strange since we can't read a sysctl value, but lets not
+			 * die yet...
+			 */
+			max = 512;
+		} else {
+			max -= (page_size / 1024);
+		}
+
+		pages = (max * 1024) / page_size;
+		if (!is_power_of_2(pages))
+			pages = rounddown_pow_of_two(pages);
+	} else if (!is_power_of_2(pages))
+		return 0;
+
+	return (pages + 1) * page_size;
+}
+
+static long parse_pages_arg(const char *str, unsigned long min,
+			    unsigned long max)
+{
+	unsigned long pages, val;
+	static struct parse_tag tags[] = {
+		{ .tag  = 'B', .mult = 1       },
+		{ .tag  = 'K', .mult = 1 << 10 },
+		{ .tag  = 'M', .mult = 1 << 20 },
+		{ .tag  = 'G', .mult = 1 << 30 },
+		{ .tag  = 0 },
+	};
+
+	if (str == NULL)
+		return -EINVAL;
+
+	val = parse_tag_value(str, tags);
+	if (val != (unsigned long) -1) {
+		/* we got file size value */
+		pages = PERF_ALIGN(val, page_size) / page_size;
+	} else {
+		/* we got pages count value */
+		char *eptr;
+		pages = strtoul(str, &eptr, 10);
+		if (*eptr != '\0')
+			return -EINVAL;
+	}
+
+	if (pages == 0 && min == 0) {
+		/* leave number of pages at 0 */
+	} else if (!is_power_of_2(pages)) {
+		/* round pages up to next power of 2 */
+		pages = roundup_pow_of_two(pages);
+		if (!pages)
+			return -EINVAL;
+		pr_info("rounding mmap pages size to %lu bytes (%lu pages)\n",
+			pages * page_size, pages);
+	}
+
+	if (pages > max)
+		return -EINVAL;
+
+	return pages;
+}
+
+int perf_evlist__parse_mmap_pages(const struct option *opt, const char *str,
+				  int unset __maybe_unused)
+{
+	unsigned int *mmap_pages = opt->value;
+	unsigned long max = UINT_MAX;
+	long pages;
+
+	if (max > SIZE_MAX / page_size)
+		max = SIZE_MAX / page_size;
+
+	pages = parse_pages_arg(str, 1, max);
+	if (pages < 0) {
+		pr_err("Invalid argument for --mmap_pages/-m\n");
+		return -1;
+	}
+
+	*mmap_pages = pages;
+	return 0;
+}
+
+/**
+ * perf_evlist__mmap - Create mmaps to receive events.
+ * @evlist: list of events
+ * @pages: map length in pages
+ * @overwrite: overwrite older events?
+ *
+ * If @overwrite is %false the user needs to signal event consumption using
+ * perf_mmap__write_tail().  Using perf_evlist__mmap_read() does this
+ * automatically.
+ *
+ * Return: %0 on success, negative error code otherwise.
+ */
+int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
+		      bool overwrite)
+{
+	struct perf_evsel *evsel;
+	const struct cpu_map *cpus = evlist->cpus;
+	const struct thread_map *threads = evlist->threads;
+	struct mmap_params mp = {
+		.prot = PROT_READ | (overwrite ? 0 : PROT_WRITE),
+	};
+
+	if (evlist->mmap == NULL && perf_evlist__alloc_mmap(evlist) < 0)
+		return -ENOMEM;
+
+	if (evlist->pollfd.entries == NULL && perf_evlist__alloc_pollfd(evlist) < 0)
+		return -ENOMEM;
+
+	evlist->overwrite = overwrite;
+	evlist->mmap_len = perf_evlist__mmap_size(pages);
+	pr_debug("mmap size %zuB\n", evlist->mmap_len);
+	mp.mask = evlist->mmap_len - page_size - 1;
+
+	evlist__for_each(evlist, evsel) {
+		if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
+		    evsel->sample_id == NULL &&
+		    perf_evsel__alloc_id(evsel, cpu_map__nr(cpus), threads->nr) < 0)
+			return -ENOMEM;
+	}
+
+	if (cpu_map__empty(cpus))
+		return perf_evlist__mmap_per_thread(evlist, &mp);
+
+	return perf_evlist__mmap_per_cpu(evlist, &mp);
+}
+
+int perf_evlist__create_maps(struct perf_evlist *evlist, struct target *target)
+{
+	evlist->threads = thread_map__new_str(target->pid, target->tid,
+					      target->uid);
+
+	if (evlist->threads == NULL)
+		return -1;
+
+	if (target__uses_dummy_map(target))
+		evlist->cpus = cpu_map__dummy_new();
+	else
+		evlist->cpus = cpu_map__new(target->cpu_list);
+
+	if (evlist->cpus == NULL)
+		goto out_delete_threads;
+
+	return 0;
+
+out_delete_threads:
+	thread_map__delete(evlist->threads);
+	evlist->threads = NULL;
+	return -1;
+}
+
+int perf_evlist__apply_filters(struct perf_evlist *evlist, struct perf_evsel **err_evsel)
+{
+	struct perf_evsel *evsel;
+	int err = 0;
+	const int ncpus = cpu_map__nr(evlist->cpus),
+		  nthreads = thread_map__nr(evlist->threads);
+
+	evlist__for_each(evlist, evsel) {
+		if (evsel->filter == NULL)
+			continue;
+
+		err = perf_evsel__set_filter(evsel, ncpus, nthreads, evsel->filter);
+		if (err) {
+			*err_evsel = evsel;
+			break;
+		}
+	}
+
+	return err;
+}
+
+int perf_evlist__set_filter(struct perf_evlist *evlist, const char *filter)
+{
+	struct perf_evsel *evsel;
+	int err = 0;
+	const int ncpus = cpu_map__nr(evlist->cpus),
+		  nthreads = thread_map__nr(evlist->threads);
+
+	evlist__for_each(evlist, evsel) {
+		err = perf_evsel__set_filter(evsel, ncpus, nthreads, filter);
+		if (err)
+			break;
+	}
+
+	return err;
+}
+
+int perf_evlist__set_filter_pids(struct perf_evlist *evlist, size_t npids, pid_t *pids)
+{
+	char *filter;
+	int ret = -1;
+	size_t i;
+
+	for (i = 0; i < npids; ++i) {
+		if (i == 0) {
+			if (asprintf(&filter, "common_pid != %d", pids[i]) < 0)
+				return -1;
+		} else {
+			char *tmp;
+
+			if (asprintf(&tmp, "%s && common_pid != %d", filter, pids[i]) < 0)
+				goto out_free;
+
+			free(filter);
+			filter = tmp;
+		}
+	}
+
+	ret = perf_evlist__set_filter(evlist, filter);
+out_free:
+	free(filter);
+	return ret;
+}
+
+int perf_evlist__set_filter_pid(struct perf_evlist *evlist, pid_t pid)
+{
+	return perf_evlist__set_filter_pids(evlist, 1, &pid);
+}
+
+bool perf_evlist__valid_sample_type(struct perf_evlist *evlist)
+{
+	struct perf_evsel *pos;
+
+	if (evlist->nr_entries == 1)
+		return true;
+
+	if (evlist->id_pos < 0 || evlist->is_pos < 0)
+		return false;
+
+	evlist__for_each(evlist, pos) {
+		if (pos->id_pos != evlist->id_pos ||
+		    pos->is_pos != evlist->is_pos)
+			return false;
+	}
+
+	return true;
+}
+
+u64 __perf_evlist__combined_sample_type(struct perf_evlist *evlist)
+{
+	struct perf_evsel *evsel;
+
+	if (evlist->combined_sample_type)
+		return evlist->combined_sample_type;
+
+	evlist__for_each(evlist, evsel)
+		evlist->combined_sample_type |= evsel->attr.sample_type;
+
+	return evlist->combined_sample_type;
+}
+
+u64 perf_evlist__combined_sample_type(struct perf_evlist *evlist)
+{
+	evlist->combined_sample_type = 0;
+	return __perf_evlist__combined_sample_type(evlist);
+}
+
+bool perf_evlist__valid_read_format(struct perf_evlist *evlist)
+{
+	struct perf_evsel *first = perf_evlist__first(evlist), *pos = first;
+	u64 read_format = first->attr.read_format;
+	u64 sample_type = first->attr.sample_type;
+
+	evlist__for_each(evlist, pos) {
+		if (read_format != pos->attr.read_format)
+			return false;
+	}
+
+	/* PERF_SAMPLE_READ imples PERF_FORMAT_ID. */
+	if ((sample_type & PERF_SAMPLE_READ) &&
+	    !(read_format & PERF_FORMAT_ID)) {
+		return false;
+	}
+
+	return true;
+}
+
+u64 perf_evlist__read_format(struct perf_evlist *evlist)
+{
+	struct perf_evsel *first = perf_evlist__first(evlist);
+	return first->attr.read_format;
+}
+
+u16 perf_evlist__id_hdr_size(struct perf_evlist *evlist)
+{
+	struct perf_evsel *first = perf_evlist__first(evlist);
+	struct perf_sample *data;
+	u64 sample_type;
+	u16 size = 0;
+
+	if (!first->attr.sample_id_all)
+		goto out;
+
+	sample_type = first->attr.sample_type;
+
+	if (sample_type & PERF_SAMPLE_TID)
+		size += sizeof(data->tid) * 2;
+
+       if (sample_type & PERF_SAMPLE_TIME)
+		size += sizeof(data->time);
+
+	if (sample_type & PERF_SAMPLE_ID)
+		size += sizeof(data->id);
+
+	if (sample_type & PERF_SAMPLE_STREAM_ID)
+		size += sizeof(data->stream_id);
+
+	if (sample_type & PERF_SAMPLE_CPU)
+		size += sizeof(data->cpu) * 2;
+
+	if (sample_type & PERF_SAMPLE_IDENTIFIER)
+		size += sizeof(data->id);
+out:
+	return size;
+}
+
+bool perf_evlist__valid_sample_id_all(struct perf_evlist *evlist)
+{
+	struct perf_evsel *first = perf_evlist__first(evlist), *pos = first;
+
+	evlist__for_each_continue(evlist, pos) {
+		if (first->attr.sample_id_all != pos->attr.sample_id_all)
+			return false;
+	}
+
+	return true;
+}
+
+bool perf_evlist__sample_id_all(struct perf_evlist *evlist)
+{
+	struct perf_evsel *first = perf_evlist__first(evlist);
+	return first->attr.sample_id_all;
+}
+
+void perf_evlist__set_selected(struct perf_evlist *evlist,
+			       struct perf_evsel *evsel)
+{
+	evlist->selected = evsel;
+}
+
+void perf_evlist__close(struct perf_evlist *evlist)
+{
+	struct perf_evsel *evsel;
+	int ncpus = cpu_map__nr(evlist->cpus);
+	int nthreads = thread_map__nr(evlist->threads);
+	int n;
+
+	evlist__for_each_reverse(evlist, evsel) {
+		n = evsel->cpus ? evsel->cpus->nr : ncpus;
+		perf_evsel__close(evsel, n, nthreads);
+	}
+}
+
+static int perf_evlist__create_syswide_maps(struct perf_evlist *evlist)
+{
+	int err = -ENOMEM;
+
+	/*
+	 * Try reading /sys/devices/system/cpu/online to get
+	 * an all cpus map.
+	 *
+	 * FIXME: -ENOMEM is the best we can do here, the cpu_map
+	 * code needs an overhaul to properly forward the
+	 * error, and we may not want to do that fallback to a
+	 * default cpu identity map :-\
+	 */
+	evlist->cpus = cpu_map__new(NULL);
+	if (evlist->cpus == NULL)
+		goto out;
+
+	evlist->threads = thread_map__new_dummy();
+	if (evlist->threads == NULL)
+		goto out_free_cpus;
+
+	err = 0;
+out:
+	return err;
+out_free_cpus:
+	cpu_map__delete(evlist->cpus);
+	evlist->cpus = NULL;
+	goto out;
+}
+
+int perf_evlist__open(struct perf_evlist *evlist)
+{
+	struct perf_evsel *evsel;
+	int err;
+
+	/*
+	 * Default: one fd per CPU, all threads, aka systemwide
+	 * as sys_perf_event_open(cpu = -1, thread = -1) is EINVAL
+	 */
+	if (evlist->threads == NULL && evlist->cpus == NULL) {
+		err = perf_evlist__create_syswide_maps(evlist);
+		if (err < 0)
+			goto out_err;
+	}
+
+	perf_evlist__update_id_pos(evlist);
+
+	evlist__for_each(evlist, evsel) {
+		err = perf_evsel__open(evsel, evlist->cpus, evlist->threads);
+		if (err < 0)
+			goto out_err;
+	}
+
+	return 0;
+out_err:
+	perf_evlist__close(evlist);
+	errno = -err;
+	return err;
+}
+
+int perf_evlist__prepare_workload(struct perf_evlist *evlist, struct target *target,
+				  const char *argv[], bool pipe_output,
+				  void (*exec_error)(int signo, siginfo_t *info, void *ucontext))
+{
+	int child_ready_pipe[2], go_pipe[2];
+	char bf;
+
+	if (pipe(child_ready_pipe) < 0) {
+		perror("failed to create 'ready' pipe");
+		return -1;
+	}
+
+	if (pipe(go_pipe) < 0) {
+		perror("failed to create 'go' pipe");
+		goto out_close_ready_pipe;
+	}
+
+	evlist->workload.pid = fork();
+	if (evlist->workload.pid < 0) {
+		perror("failed to fork");
+		goto out_close_pipes;
+	}
+
+	if (!evlist->workload.pid) {
+		int ret;
+
+		if (pipe_output)
+			dup2(2, 1);
+
+		signal(SIGTERM, SIG_DFL);
+
+		close(child_ready_pipe[0]);
+		close(go_pipe[1]);
+		fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC);
+
+		/*
+		 * Tell the parent we're ready to go
+		 */
+		close(child_ready_pipe[1]);
+
+		/*
+		 * Wait until the parent tells us to go.
+		 */
+		ret = read(go_pipe[0], &bf, 1);
+		/*
+		 * The parent will ask for the execvp() to be performed by
+		 * writing exactly one byte, in workload.cork_fd, usually via
+		 * perf_evlist__start_workload().
+		 *
+		 * For cancelling the workload without actually running it,
+		 * the parent will just close workload.cork_fd, without writing
+		 * anything, i.e. read will return zero and we just exit()
+		 * here.
+		 */
+		if (ret != 1) {
+			if (ret == -1)
+				perror("unable to read pipe");
+			exit(ret);
+		}
+
+		execvp(argv[0], (char **)argv);
+
+		if (exec_error) {
+			union sigval val;
+
+			val.sival_int = errno;
+			if (sigqueue(getppid(), SIGUSR1, val))
+				perror(argv[0]);
+		} else
+			perror(argv[0]);
+		exit(-1);
+	}
+
+	if (exec_error) {
+		struct sigaction act = {
+			.sa_flags     = SA_SIGINFO,
+			.sa_sigaction = exec_error,
+		};
+		sigaction(SIGUSR1, &act, NULL);
+	}
+
+	if (target__none(target)) {
+		if (evlist->threads == NULL) {
+			fprintf(stderr, "FATAL: evlist->threads need to be set at this point (%s:%d).\n",
+				__func__, __LINE__);
+			goto out_close_pipes;
+		}
+		evlist->threads->map[0] = evlist->workload.pid;
+	}
+
+	close(child_ready_pipe[1]);
+	close(go_pipe[0]);
+	/*
+	 * wait for child to settle
+	 */
+	if (read(child_ready_pipe[0], &bf, 1) == -1) {
+		perror("unable to read pipe");
+		goto out_close_pipes;
+	}
+
+	fcntl(go_pipe[1], F_SETFD, FD_CLOEXEC);
+	evlist->workload.cork_fd = go_pipe[1];
+	close(child_ready_pipe[0]);
+	return 0;
+
+out_close_pipes:
+	close(go_pipe[0]);
+	close(go_pipe[1]);
+out_close_ready_pipe:
+	close(child_ready_pipe[0]);
+	close(child_ready_pipe[1]);
+	return -1;
+}
+
+int perf_evlist__start_workload(struct perf_evlist *evlist)
+{
+	if (evlist->workload.cork_fd > 0) {
+		char bf = 0;
+		int ret;
+		/*
+		 * Remove the cork, let it rip!
+		 */
+		ret = write(evlist->workload.cork_fd, &bf, 1);
+		if (ret < 0)
+			perror("enable to write to pipe");
+
+		close(evlist->workload.cork_fd);
+		return ret;
+	}
+
+	return 0;
+}
+
+int perf_evlist__parse_sample(struct perf_evlist *evlist, union perf_event *event,
+			      struct perf_sample *sample)
+{
+	struct perf_evsel *evsel = perf_evlist__event2evsel(evlist, event);
+
+	if (!evsel)
+		return -EFAULT;
+	return perf_evsel__parse_sample(evsel, event, sample);
+}
+
+size_t perf_evlist__fprintf(struct perf_evlist *evlist, FILE *fp)
+{
+	struct perf_evsel *evsel;
+	size_t printed = 0;
+
+	evlist__for_each(evlist, evsel) {
+		printed += fprintf(fp, "%s%s", evsel->idx ? ", " : "",
+				   perf_evsel__name(evsel));
+	}
+
+	return printed + fprintf(fp, "\n");
+}
+
+int perf_evlist__strerror_open(struct perf_evlist *evlist __maybe_unused,
+			       int err, char *buf, size_t size)
+{
+	int printed, value;
+	char sbuf[STRERR_BUFSIZE], *emsg = strerror_r(err, sbuf, sizeof(sbuf));
+
+	switch (err) {
+	case EACCES:
+	case EPERM:
+		printed = scnprintf(buf, size,
+				    "Error:\t%s.\n"
+				    "Hint:\tCheck /proc/sys/kernel/perf_event_paranoid setting.", emsg);
+
+		value = perf_event_paranoid();
+
+		printed += scnprintf(buf + printed, size - printed, "\nHint:\t");
+
+		if (value >= 2) {
+			printed += scnprintf(buf + printed, size - printed,
+					     "For your workloads it needs to be <= 1\nHint:\t");
+		}
+		printed += scnprintf(buf + printed, size - printed,
+				     "For system wide tracing it needs to be set to -1.\n");
+
+		printed += scnprintf(buf + printed, size - printed,
+				    "Hint:\tTry: 'sudo sh -c \"echo -1 > /proc/sys/kernel/perf_event_paranoid\"'\n"
+				    "Hint:\tThe current value is %d.", value);
+		break;
+	default:
+		scnprintf(buf, size, "%s", emsg);
+		break;
+	}
+
+	return 0;
+}
+
+int perf_evlist__strerror_mmap(struct perf_evlist *evlist, int err, char *buf, size_t size)
+{
+	char sbuf[STRERR_BUFSIZE], *emsg = strerror_r(err, sbuf, sizeof(sbuf));
+	int pages_attempted = evlist->mmap_len / 1024, pages_max_per_user, printed = 0;
+
+	switch (err) {
+	case EPERM:
+		sysctl__read_int("kernel/perf_event_mlock_kb", &pages_max_per_user);
+		printed += scnprintf(buf + printed, size - printed,
+				     "Error:\t%s.\n"
+				     "Hint:\tCheck /proc/sys/kernel/perf_event_mlock_kb (%d kB) setting.\n"
+				     "Hint:\tTried using %zd kB.\n",
+				     emsg, pages_max_per_user, pages_attempted);
+
+		if (pages_attempted >= pages_max_per_user) {
+			printed += scnprintf(buf + printed, size - printed,
+					     "Hint:\tTry 'sudo sh -c \"echo %d > /proc/sys/kernel/perf_event_mlock_kb\"', or\n",
+					     pages_max_per_user + pages_attempted);
+		}
+
+		printed += scnprintf(buf + printed, size - printed,
+				     "Hint:\tTry using a smaller -m/--mmap-pages value.");
+		break;
+	default:
+		scnprintf(buf, size, "%s", emsg);
+		break;
+	}
+
+	return 0;
+}
+
+void perf_evlist__to_front(struct perf_evlist *evlist,
+			   struct perf_evsel *move_evsel)
+{
+	struct perf_evsel *evsel, *n;
+	LIST_HEAD(move);
+
+	if (move_evsel == perf_evlist__first(evlist))
+		return;
+
+	evlist__for_each_safe(evlist, n, evsel) {
+		if (evsel->leader == move_evsel->leader)
+			list_move_tail(&evsel->node, &move);
+	}
+
+	list_splice(&move, &evlist->entries);
+}
+
+void perf_evlist__set_tracking_event(struct perf_evlist *evlist,
+				     struct perf_evsel *tracking_evsel)
+{
+	struct perf_evsel *evsel;
+
+	if (tracking_evsel->tracking)
+		return;
+
+	evlist__for_each(evlist, evsel) {
+		if (evsel != tracking_evsel)
+			evsel->tracking = false;
+	}
+
+	tracking_evsel->tracking = true;
+}