diff mbox

[v8,2/8] perf evlist: Introduce aux evlist

Message ID 1466419645-75551-3-git-send-email-wangnan0@huawei.com
State Superseded
Headers show

Commit Message

Wang Nan June 20, 2016, 10:47 a.m. UTC 
An auxiliary evlist is created by perf_evlist__new_aux() using an
existing evlist as its parent. An auxiliary evlist can have its own
'struct perf_mmap', but can't have any other data. User should use its
parent instead when accessing other data.

Auxiliary evlists are containers of 'struct perf_mmap'. It is introduced
to allow its parent evlist to map different events into separated mmaps.

Following commits create an auxiliary evlist for overwritable
events, because overwritable events need a read only and backwards ring
buffer, which is different from normal events.

To achieve this goal, this patch carefully changes 'evlist' to
'evlist->parent' in all functions in the path of 'perf_evlist__mmap_ex',
except 'evlist->mmap' related operations, to make sure all evlist
modifications (like pollfd and event id hash tables) goes to original
evlist.

A 'evlist->parent' pointer is added to 'struct perf_evlist' and points to
the evlist itself for normal evlists.

Children of one evlist are linked into it so one can find all children
from its parent.

To avoid potential complexity, forbid creating aux evlist from another
aux evlist.

Improve perf_evlist__munmap_filtered(), so when recording, if an event
is terminated, unmap mmaps, from parent and children.

Signed-off-by: Wang Nan <wangnan0@huawei.com>

Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
---
 tools/perf/util/evlist.c | 49 +++++++++++++++++++++++++++++++++++++-----------
 tools/perf/util/evlist.h | 12 ++++++++++++
 2 files changed, 50 insertions(+), 11 deletions(-)

-- 
1.8.3.4

Comments

Wang Nan June 21, 2016, 1:31 a.m. UTC | #1 
On 2016/6/21 4:36, Arnaldo Carvalho de Melo wrote:
> Em Mon, Jun 20, 2016 at 10:47:19AM +0000, Wang Nan escreveu:

>> An auxiliary evlist is created by perf_evlist__new_aux() using an

>> existing evlist as its parent. An auxiliary evlist can have its own

>> 'struct perf_mmap', but can't have any other data. User should use its

>> parent instead when accessing other data.

>>

>> Auxiliary evlists are containers of 'struct perf_mmap'. It is introduced

>> to allow its parent evlist to map different events into separated mmaps.

>>

>> Following commits create an auxiliary evlist for overwritable

>> events, because overwritable events need a read only and backwards ring

>> buffer, which is different from normal events.

>>

>> To achieve this goal, this patch carefully changes 'evlist' to

>> 'evlist->parent' in all functions in the path of 'perf_evlist__mmap_ex',

>> except 'evlist->mmap' related operations, to make sure all evlist

>> modifications (like pollfd and event id hash tables) goes to original

>> evlist.

>>

>> A 'evlist->parent' pointer is added to 'struct perf_evlist' and points to

>> the evlist itself for normal evlists.

>>

>> Children of one evlist are linked into it so one can find all children

>> from its parent.

>> To avoid potential complexity, forbid creating aux evlist from another

>> aux evlist.

>>

>> Improve perf_evlist__munmap_filtered(), so when recording, if an event

>> is terminated, unmap mmaps, from parent and children.

>   

>> Signed-off-by: Wang Nan <wangnan0@huawei.com>

>> Cc: He Kuang <hekuang@huawei.com>

>> Cc: Jiri Olsa <jolsa@kernel.org>

>> Cc: Masami Hiramatsu <mhiramat@kernel.org>

>> Cc: Namhyung Kim <namhyung@kernel.org>

>> Cc: Zefan Li <lizefan@huawei.com>

>> Cc: pi3orama@163.com

>> ---

>>   tools/perf/util/evlist.c | 49 +++++++++++++++++++++++++++++++++++++-----------

>>   tools/perf/util/evlist.h | 12 ++++++++++++

>>   2 files changed, 50 insertions(+), 11 deletions(-)


[SNIP]

>> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h

>> index 68cb136..5b50692 100644

>> --- a/tools/perf/util/evlist.h

>> +++ b/tools/perf/util/evlist.h

>> @@ -37,6 +37,10 @@ struct perf_mmap {

>>   

>>   struct perf_evlist {

>>   	struct list_head entries;

>> +	union {

>> +		struct list_head children;

>> +		struct list_head list;

> This is something new, right, i.e. having a list of evlists from a

> parent evlist, one where there can be at most one level, i.e. no

> grandchildrens...

>

> Is this strictly needed? I.e. the existing code calling

> perf_evlist__munmap_filtered() has just the parent pointer and thus, to

> not change it we need to have a way to go the children?

>

> Also, can you se a parent with more than one child?


If we further restrict aux evlist and parent list, allow only one aux
evlist for a parent, we can avoid the linked list. Simply linking parent
and child using pointers would be enough.

However, I plan to introduce multiple children for a parent. There are
two possible aux evlists:

   1. Trigger aux evlist: we can use BPF script to measure events, and 
do something
      (dumpping, printing, computing, reporting...) when it detect something
      (for example, FPS drop to 10 frames/sec). We can create a bpf-output
      event and put it in a separated aux evlist with buffering turned off,
      so once BPF script generate a event perf receives it immediately.

   2. Non-sampling aux evlist: we can use a dummy event to collect fork, 
comm
      and mmap{,2} events in a separated aux evlist. We can use this 
evlist to
      maintain system state during recording, so we can totally solve 
the problem
      describe in patch 8/8.

Thank you.
diff mbox

Patch

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 1b918aa..b03cb3c 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -41,10 +41,12 @@  void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus,
 	for (i = 0; i < PERF_EVLIST__HLIST_SIZE; ++i)
 		INIT_HLIST_HEAD(&evlist->heads[i]);
 	INIT_LIST_HEAD(&evlist->entries);
+	INIT_LIST_HEAD(&evlist->children);
 	perf_evlist__set_maps(evlist, cpus, threads);
 	fdarray__init(&evlist->pollfd, 64);
 	evlist->workload.pid = -1;
 	evlist->backward = false;
+	evlist->parent = evlist;
 }
 
 struct perf_evlist *perf_evlist__new(void)
@@ -487,13 +489,17 @@  static void perf_evlist__munmap_filtered(struct fdarray *fda, int fd,
 					 void *arg __maybe_unused)
 {
 	struct perf_evlist *evlist = container_of(fda, struct perf_evlist, pollfd);
+	struct perf_evlist *child;
 
 	perf_evlist__mmap_put(evlist, fda->priv[fd].idx);
+	list_for_each_entry(child, &evlist->children, list)
+		perf_evlist__mmap_put(child, 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,
+	return fdarray__filter(&evlist->parent->pollfd, revents_and_mask,
 			       perf_evlist__munmap_filtered, NULL);
 }
 
@@ -1012,7 +1018,7 @@  static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
 	struct perf_evsel *evsel;
 	int revent;
 
-	evlist__for_each(evlist, evsel) {
+	evlist__for_each(evlist->parent, evsel) {
 		int fd;
 
 		if (evsel->overwrite != (evlist->overwrite && evlist->backward))
@@ -1044,16 +1050,16 @@  static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
 		 * Therefore don't add it for polling.
 		 */
 		if (!evsel->system_wide &&
-		    __perf_evlist__add_pollfd(evlist, fd, idx, revent) < 0) {
+		    __perf_evlist__add_pollfd(evlist->parent, fd, idx, revent) < 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,
+			if (perf_evlist__id_add_fd(evlist->parent, evsel, cpu, thread,
 						   fd) < 0)
 				return -1;
-			perf_evlist__set_sid_idx(evlist, evsel, idx, cpu,
+			perf_evlist__set_sid_idx(evlist->parent, evsel, idx, cpu,
 						 thread);
 		}
 	}
@@ -1094,13 +1100,13 @@  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);
+	int nr_threads = thread_map__nr(evlist->parent->threads);
 
 	pr_debug2("perf event ring buffer mmapped per thread\n");
 	for (thread = 0; thread < nr_threads; thread++) {
 		int output = -1;
 
-		auxtrace_mmap_params__set_idx(&mp->auxtrace_mp, evlist, thread,
+		auxtrace_mmap_params__set_idx(&mp->auxtrace_mp, evlist->parent, thread,
 					      false);
 
 		if (perf_evlist__mmap_per_evsel(evlist, thread, mp, 0, thread,
@@ -1239,8 +1245,8 @@  int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
 			 bool auxtrace_overwrite)
 {
 	struct perf_evsel *evsel;
-	const struct cpu_map *cpus = evlist->cpus;
-	const struct thread_map *threads = evlist->threads;
+	const struct cpu_map *cpus = evlist->parent->cpus;
+	const struct thread_map *threads = evlist->parent->threads;
 	struct mmap_params mp = {
 		.prot = PROT_READ | (overwrite ? 0 : PROT_WRITE),
 	};
@@ -1248,7 +1254,7 @@  int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
 	if (evlist->mmap == NULL && perf_evlist__alloc_mmap(evlist) < 0)
 		return -ENOMEM;
 
-	if (evlist->pollfd.entries == NULL && perf_evlist__alloc_pollfd(evlist) < 0)
+	if (evlist->parent->pollfd.entries == NULL && perf_evlist__alloc_pollfd(evlist->parent) < 0)
 		return -ENOMEM;
 
 	evlist->overwrite = overwrite;
@@ -1259,7 +1265,7 @@  int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
 	auxtrace_mmap_params__init(&mp.auxtrace_mp, evlist->mmap_len,
 				   auxtrace_pages, auxtrace_overwrite);
 
-	evlist__for_each(evlist, evsel) {
+	evlist__for_each(evlist->parent, 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)
@@ -1916,3 +1922,24 @@  perf_evlist__find_evsel_by_str(struct perf_evlist *evlist,
 
 	return NULL;
 }
+
+struct perf_evlist *perf_evlist__new_aux(struct perf_evlist *parent)
+{
+	struct perf_evlist *evlist;
+
+	if (perf_evlist__is_aux(parent)) {
+		pr_err("Internal error: create aux evlist from another aux evlist\n");
+		return NULL;
+	}
+
+	evlist = zalloc(sizeof(*evlist));
+	if (!evlist)
+		return NULL;
+
+	perf_evlist__init(evlist, parent->cpus, parent->threads);
+	evlist->parent = parent->parent;
+	INIT_LIST_HEAD(&evlist->list);
+	list_add(&evlist->list, &parent->children);
+
+	return evlist;
+}
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 68cb136..5b50692 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -37,6 +37,10 @@  struct perf_mmap {
 
 struct perf_evlist {
 	struct list_head entries;
+	union {
+		struct list_head children;
+		struct list_head list;
+	};
 	struct hlist_head heads[PERF_EVLIST__HLIST_SIZE];
 	int		 nr_entries;
 	int		 nr_groups;
@@ -60,8 +64,14 @@  struct perf_evlist {
 	struct perf_evsel *selected;
 	struct events_stats stats;
 	struct perf_env	*env;
+	struct perf_evlist *parent;
 };
 
+static inline bool perf_evlist__is_aux(struct perf_evlist *evlist)
+{
+	return evlist->parent != evlist;
+}
+
 struct perf_evsel_str_handler {
 	const char *name;
 	void	   *handler;
@@ -70,6 +80,8 @@  struct perf_evsel_str_handler {
 struct perf_evlist *perf_evlist__new(void);
 struct perf_evlist *perf_evlist__new_default(void);
 struct perf_evlist *perf_evlist__new_dummy(void);
+struct perf_evlist *perf_evlist__new_aux(struct perf_evlist *);
+
 void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus,
 		       struct thread_map *threads);
 void perf_evlist__exit(struct perf_evlist *evlist);