perf evsel: Fix use of inherit

perf stat doesn't mmap and its perfectly fine for it to use task-bound counters with inheritance. So set the attr.inherit on the caller and leave the syscall itself to validate it. When the mmap fails perf_evlist__mmap will just emit a warning if this is the failure reason. Reported-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> 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> Link: http://lkml.kernel.org/r/20110414170121.GC3229@ghostprotocols.net Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

perf evsel: Fix use of inherit
perf stat doesn't mmap and its perfectly fine for it to use task-bound counters with inheritance. So set the attr.inherit on the caller and leave the syscall itself to validate it. When the mmap fails perf_evlist__mmap will just emit a warning if this is the failure reason. Reported-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> 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> Link: http://lkml.kernel.org/r/20110414170121.GC3229@ghostprotocols.net Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Arnaldo Carvalho de Melo
1 parent db9a9cbc81
Showing 8 changed files with 41 additions and 42 deletions Side-by-side Diff
tools/perf/builtin-record.c
tools/perf/builtin-stat.c
tools/perf/builtin-test.c
tools/perf/builtin-top.c
tools/perf/util/evlist.c
tools/perf/util/evsel.c
tools/perf/util/evsel.h
tools/perf/util/python.c
@@ -163,6 +163,7 @@
 	struct perf_event_attr *attr = &evsel->attr;
 	int track = !evsel->idx; /* only the first counter needs these */
  
+	attr->inherit		= !no_inherit;
 	attr->read_format	= PERF_FORMAT_TOTAL_TIME_ENABLED |
 				  PERF_FORMAT_TOTAL_TIME_RUNNING |
 				  PERF_FORMAT_ID;
@@ -251,6 +252,9 @@
 {
 	struct perf_evsel *pos;
  
+	if (evlist->cpus->map[0] < 0)
+		no_inherit = true;
+
 	list_for_each_entry(pos, &evlist->entries, node) {
 		struct perf_event_attr *attr = &pos->attr;
 		/*
@@ -271,8 +275,7 @@
 retry_sample_id:
 		attr->sample_id_all = sample_id_all_avail ? 1 : 0;
 try_again:
-		if (perf_evsel__open(pos, evlist->cpus, evlist->threads, group,
-				     !no_inherit) < 0) {
+		if (perf_evsel__open(pos, evlist->cpus, evlist->threads, group) < 0) {
 			int err = errno;
  
 			if (err == EPERM || err == EACCES) {
@@ -167,16 +167,17 @@
 		attr->read_format = PERF_FORMAT_TOTAL_TIME_ENABLED |
 				    PERF_FORMAT_TOTAL_TIME_RUNNING;
  
+	attr->inherit = !no_inherit;
+
 	if (system_wide)
-		return perf_evsel__open_per_cpu(evsel, evsel_list->cpus, false, false);
+		return perf_evsel__open_per_cpu(evsel, evsel_list->cpus, false);
  
-	attr->inherit = !no_inherit;
 	if (target_pid == -1 && target_tid == -1) {
 		attr->disabled = 1;
 		attr->enable_on_exec = 1;
 	}
  
-	return perf_evsel__open_per_thread(evsel, evsel_list->threads, false, false);
+	return perf_evsel__open_per_thread(evsel, evsel_list->threads, false);
 }
  
 /*
@@ -290,7 +290,7 @@
 		goto out_thread_map_delete;
 	}
  
-	if (perf_evsel__open_per_thread(evsel, threads, false, false) < 0) {
+	if (perf_evsel__open_per_thread(evsel, threads, false) < 0) {
 		pr_debug("failed to open counter: %s, "
 			 "tweak /proc/sys/kernel/perf_event_paranoid?\n",
 			 strerror(errno));
@@ -303,7 +303,7 @@
 	}
  
 	if (perf_evsel__read_on_cpu(evsel, 0, 0) < 0) {
-		pr_debug("perf_evsel__open_read_on_cpu\n");
+		pr_debug("perf_evsel__read_on_cpu\n");
 		goto out_close_fd;
 	}
  
@@ -365,7 +365,7 @@
 		goto out_thread_map_delete;
 	}
  
-	if (perf_evsel__open(evsel, cpus, threads, false, false) < 0) {
+	if (perf_evsel__open(evsel, cpus, threads, false) < 0) {
 		pr_debug("failed to open counter: %s, "
 			 "tweak /proc/sys/kernel/perf_event_paranoid?\n",
 			 strerror(errno));
@@ -418,7 +418,7 @@
 			continue;
  
 		if (perf_evsel__read_on_cpu(evsel, cpu, 0) < 0) {
-			pr_debug("perf_evsel__open_read_on_cpu\n");
+			pr_debug("perf_evsel__read_on_cpu\n");
 			err = -1;
 			break;
 		}
@@ -529,7 +529,7 @@
  
 		perf_evlist__add(evlist, evsels[i]);
  
-		if (perf_evsel__open(evsels[i], cpus, threads, false, false) < 0) {
+		if (perf_evsel__open(evsels[i], cpus, threads, false) < 0) {
 			pr_debug("failed to open counter: %s, "
 				 "tweak /proc/sys/kernel/perf_event_paranoid?\n",
 				 strerror(errno));
@@ -845,9 +845,10 @@
 		}
  
 		attr->mmap = 1;
+		attr->inherit = inherit;
 try_again:
 		if (perf_evsel__open(counter, top.evlist->cpus,
-				     top.evlist->threads, group, inherit) < 0) {
+				     top.evlist->threads, group) < 0) {
 			int err = errno;
  
 			if (err == EPERM || err == EACCES) {
@@ -12,6 +12,7 @@
 #include "evlist.h"
 #include "evsel.h"
 #include "util.h"
+#include "debug.h"
  
 #include <sys/mman.h>
  
  
  
@@ -250,15 +251,19 @@
 	return evlist->mmap != NULL ? 0 : -ENOMEM;
 }
  
-static int __perf_evlist__mmap(struct perf_evlist *evlist, int cpu, int prot,
-			       int mask, int fd)
+static int __perf_evlist__mmap(struct perf_evlist *evlist, struct perf_evsel *evsel,
+			       int cpu, int prot, int mask, int fd)
 {
 	evlist->mmap[cpu].prev = 0;
 	evlist->mmap[cpu].mask = mask;
 	evlist->mmap[cpu].base = mmap(NULL, evlist->mmap_len, prot,
 				      MAP_SHARED, fd, 0);
-	if (evlist->mmap[cpu].base == MAP_FAILED)
+	if (evlist->mmap[cpu].base == MAP_FAILED) {
+		if (evlist->cpus->map[cpu] == -1 && evsel->attr.inherit)
+			ui__warning("Inherit is not allowed on per-task "
+				    "events using mmap.\n");
 		return -1;
+	}
  
 	perf_evlist__add_pollfd(evlist, fd);
 	return 0;
@@ -312,7 +317,8 @@
 					if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT,
 						  FD(first_evsel, cpu, 0)) != 0)
 						goto out_unmap;
-				} else if (__perf_evlist__mmap(evlist, cpu, prot, mask, fd) < 0)
+				} else if (__perf_evlist__mmap(evlist, evsel, cpu,
+							       prot, mask, fd) < 0)
 					goto out_unmap;
  
 				if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
@@ -175,7 +175,7 @@
 }
  
 static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
-			      struct thread_map *threads, bool group, bool inherit)
+			      struct thread_map *threads, bool group)
 {
 	int cpu, thread;
 	unsigned long flags = 0;
@@ -192,19 +192,6 @@
  
 	for (cpu = 0; cpu < cpus->nr; cpu++) {
 		int group_fd = -1;
-		/*
-		 * Don't allow mmap() of inherited per-task counters. This
-		 * would create a performance issue due to all children writing
-		 * to the same buffer.
-		 *
-		 * FIXME:
-		 * Proper fix is not to pass 'inherit' to perf_evsel__open*,
-		 * but a 'flags' parameter, with 'group' folded there as well,
-		 * then introduce a PERF_O_{MMAP,GROUP,INHERIT} enum, and if
-		 * O_MMAP is set, emit a warning if cpu < 0 and O_INHERIT is
-		 * set. Lets go for the minimal fix first tho.
-		 */
-		evsel->attr.inherit = (cpus->map[cpu] >= 0) && inherit;
  
 		for (thread = 0; thread < threads->nr; thread++) {
  
@@ -253,7 +240,7 @@
 };
  
 int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
-		     struct thread_map *threads, bool group, bool inherit)
+		     struct thread_map *threads, bool group)
 {
 	if (cpus == NULL) {
 		/* Work around old compiler warnings about strict aliasing */
  
  
  
  
@@ -263,19 +250,19 @@
 	if (threads == NULL)
 		threads = &empty_thread_map.map;
  
-	return __perf_evsel__open(evsel, cpus, threads, group, inherit);
+	return __perf_evsel__open(evsel, cpus, threads, group);
 }
  
 int perf_evsel__open_per_cpu(struct perf_evsel *evsel,
-			     struct cpu_map *cpus, bool group, bool inherit)
+			     struct cpu_map *cpus, bool group)
 {
-	return __perf_evsel__open(evsel, cpus, &empty_thread_map.map, group, inherit);
+	return __perf_evsel__open(evsel, cpus, &empty_thread_map.map, group);
 }
  
 int perf_evsel__open_per_thread(struct perf_evsel *evsel,
-				struct thread_map *threads, bool group, bool inherit)
+				struct thread_map *threads, bool group)
 {
-	return __perf_evsel__open(evsel, &empty_cpu_map.map, threads, group, inherit);
+	return __perf_evsel__open(evsel, &empty_cpu_map.map, threads, group);
 }
  
 static int perf_event__parse_id_sample(const union perf_event *event, u64 type,
@@ -81,11 +81,11 @@
 void perf_evsel__close_fd(struct perf_evsel *evsel, int ncpus, int nthreads);
  
 int perf_evsel__open_per_cpu(struct perf_evsel *evsel,
-			     struct cpu_map *cpus, bool group, bool inherit);
+			     struct cpu_map *cpus, bool group);
 int perf_evsel__open_per_thread(struct perf_evsel *evsel,
-				struct thread_map *threads, bool group, bool inherit);
+				struct thread_map *threads, bool group);
 int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
-		     struct thread_map *threads, bool group, bool inherit);
+		     struct thread_map *threads, bool group);
  
 #define perf_evsel__match(evsel, t, c)		\
 	(evsel->attr.type == PERF_TYPE_##t &&	\
@@ -498,11 +498,11 @@
 	struct cpu_map *cpus = NULL;
 	struct thread_map *threads = NULL;
 	PyObject *pcpus = NULL, *pthreads = NULL;
-	int group = 0, overwrite = 0;
-	static char *kwlist[] = {"cpus", "threads", "group", "overwrite", NULL, NULL};
+	int group = 0, inherit = 0;
+	static char *kwlist[] = {"cpus", "threads", "group", "inherit", NULL, NULL};
  
 	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|OOii", kwlist,
-					 &pcpus, &pthreads, &group, &overwrite))
+					 &pcpus, &pthreads, &group, &inherit))
 		return NULL;
  
 	if (pthreads != NULL)
@@ -511,7 +511,8 @@
 	if (pcpus != NULL)
 		cpus = ((struct pyrf_cpu_map *)pcpus)->cpus;
  
-	if (perf_evsel__open(evsel, cpus, threads, group, overwrite) < 0) {
+	evsel->attr.inherit = inherit;
+	if (perf_evsel__open(evsel, cpus, threads, group) < 0) {
 		PyErr_SetFromErrno(PyExc_OSError);
 		return NULL;
 	}
...	...	@@ -163,6 +163,7 @@
163	163	struct perf_event_attr *attr = &evsel->attr;
164	164	int track = !evsel->idx; /* only the first counter needs these */
165	165
	166	+ attr->inherit = !no_inherit;
166	167	attr->read_format = PERF_FORMAT_TOTAL_TIME_ENABLED \|
167	168	PERF_FORMAT_TOTAL_TIME_RUNNING \|
168	169	PERF_FORMAT_ID;
...	...	@@ -251,6 +252,9 @@
251	252	{
252	253	struct perf_evsel *pos;
253	254
	255	+ if (evlist->cpus->map[0] < 0)
	256	+ no_inherit = true;
	257	+
254	258	list_for_each_entry(pos, &evlist->entries, node) {
255	259	struct perf_event_attr *attr = &pos->attr;
256	260	/*
...	...	@@ -271,8 +275,7 @@
271	275	retry_sample_id:
272	276	attr->sample_id_all = sample_id_all_avail ? 1 : 0;
273	277	try_again:
274		- if (perf_evsel__open(pos, evlist->cpus, evlist->threads, group,
275		- !no_inherit) < 0) {
	278	+ if (perf_evsel__open(pos, evlist->cpus, evlist->threads, group) < 0) {
276	279	int err = errno;
277	280
278	281	if (err == EPERM \|\| err == EACCES) {
...	...	@@ -167,16 +167,17 @@
167	167	attr->read_format = PERF_FORMAT_TOTAL_TIME_ENABLED \|
168	168	PERF_FORMAT_TOTAL_TIME_RUNNING;
169	169
	170	+ attr->inherit = !no_inherit;
	171	+
170	172	if (system_wide)
171		- return perf_evsel__open_per_cpu(evsel, evsel_list->cpus, false, false);
	173	+ return perf_evsel__open_per_cpu(evsel, evsel_list->cpus, false);
172	174
173		- attr->inherit = !no_inherit;
174	175	if (target_pid == -1 && target_tid == -1) {
175	176	attr->disabled = 1;
176	177	attr->enable_on_exec = 1;
177	178	}
178	179
179		- return perf_evsel__open_per_thread(evsel, evsel_list->threads, false, false);
	180	+ return perf_evsel__open_per_thread(evsel, evsel_list->threads, false);
180	181	}
181	182
182	183	/*
...	...	@@ -290,7 +290,7 @@
290	290	goto out_thread_map_delete;
291	291	}
292	292
293		- if (perf_evsel__open_per_thread(evsel, threads, false, false) < 0) {
	293	+ if (perf_evsel__open_per_thread(evsel, threads, false) < 0) {
294	294	pr_debug("failed to open counter: %s, "
295	295	"tweak /proc/sys/kernel/perf_event_paranoid?\n",
296	296	strerror(errno));
...	...	@@ -303,7 +303,7 @@
303	303	}
304	304
305	305	if (perf_evsel__read_on_cpu(evsel, 0, 0) < 0) {
306		- pr_debug("perf_evsel__open_read_on_cpu\n");
	306	+ pr_debug("perf_evsel__read_on_cpu\n");
307	307	goto out_close_fd;
308	308	}
309	309
...	...	@@ -365,7 +365,7 @@
365	365	goto out_thread_map_delete;
366	366	}
367	367
368		- if (perf_evsel__open(evsel, cpus, threads, false, false) < 0) {
	368	+ if (perf_evsel__open(evsel, cpus, threads, false) < 0) {
369	369	pr_debug("failed to open counter: %s, "
370	370	"tweak /proc/sys/kernel/perf_event_paranoid?\n",
371	371	strerror(errno));
...	...	@@ -418,7 +418,7 @@
418	418	continue;
419	419
420	420	if (perf_evsel__read_on_cpu(evsel, cpu, 0) < 0) {
421		- pr_debug("perf_evsel__open_read_on_cpu\n");
	421	+ pr_debug("perf_evsel__read_on_cpu\n");
422	422	err = -1;
423	423	break;
424	424	}
...	...	@@ -529,7 +529,7 @@
529	529
530	530	perf_evlist__add(evlist, evsels[i]);
531	531
532		- if (perf_evsel__open(evsels[i], cpus, threads, false, false) < 0) {
	532	+ if (perf_evsel__open(evsels[i], cpus, threads, false) < 0) {
533	533	pr_debug("failed to open counter: %s, "
534	534	"tweak /proc/sys/kernel/perf_event_paranoid?\n",
535	535	strerror(errno));
...	...	@@ -845,9 +845,10 @@
845	845	}
846	846
847	847	attr->mmap = 1;
	848	+ attr->inherit = inherit;
848	849	try_again:
849	850	if (perf_evsel__open(counter, top.evlist->cpus,
850		- top.evlist->threads, group, inherit) < 0) {
	851	+ top.evlist->threads, group) < 0) {
851	852	int err = errno;
852	853
853	854	if (err == EPERM \|\| err == EACCES) {
...	...	@@ -12,6 +12,7 @@
12	12	#include "evlist.h"
13	13	#include "evsel.h"
14	14	#include "util.h"
	15	+#include "debug.h"
15	16
16	17	#include <sys/mman.h>
17	18
18	19
19	20
...	...	@@ -250,15 +251,19 @@
250	251	return evlist->mmap != NULL ? 0 : -ENOMEM;
251	252	}
252	253
253		-static int __perf_evlist__mmap(struct perf_evlist *evlist, int cpu, int prot,
254		- int mask, int fd)
	254	+static int __perf_evlist__mmap(struct perf_evlist evlist, struct perf_evsel evsel,
	255	+ int cpu, int prot, int mask, int fd)
255	256	{
256	257	evlist->mmap[cpu].prev = 0;
257	258	evlist->mmap[cpu].mask = mask;
258	259	evlist->mmap[cpu].base = mmap(NULL, evlist->mmap_len, prot,
259	260	MAP_SHARED, fd, 0);
260		- if (evlist->mmap[cpu].base == MAP_FAILED)
	261	+ if (evlist->mmap[cpu].base == MAP_FAILED) {
	262	+ if (evlist->cpus->map[cpu] == -1 && evsel->attr.inherit)
	263	+ ui__warning("Inherit is not allowed on per-task "
	264	+ "events using mmap.\n");
261	265	return -1;
	266	+ }
262	267
263	268	perf_evlist__add_pollfd(evlist, fd);
264	269	return 0;
...	...	@@ -312,7 +317,8 @@
312	317	if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT,
313	318	FD(first_evsel, cpu, 0)) != 0)
314	319	goto out_unmap;
315		- } else if (__perf_evlist__mmap(evlist, cpu, prot, mask, fd) < 0)
	320	+ } else if (__perf_evlist__mmap(evlist, evsel, cpu,
	321	+ prot, mask, fd) < 0)
316	322	goto out_unmap;
317	323
318	324	if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
...	...	@@ -175,7 +175,7 @@
175	175	}
176	176
177	177	static int __perf_evsel__open(struct perf_evsel evsel, struct cpu_map cpus,
178		- struct thread_map *threads, bool group, bool inherit)
	178	+ struct thread_map *threads, bool group)
179	179	{
180	180	int cpu, thread;
181	181	unsigned long flags = 0;
...	...	@@ -192,19 +192,6 @@
192	192
193	193	for (cpu = 0; cpu < cpus->nr; cpu++) {
194	194	int group_fd = -1;
195		- /*
196		- * Don't allow mmap() of inherited per-task counters. This
197		- * would create a performance issue due to all children writing
198		- * to the same buffer.
199		- *
200		- * FIXME:
201		- * Proper fix is not to pass 'inherit' to perf_evsel__open*,
202		- * but a 'flags' parameter, with 'group' folded there as well,
203		- * then introduce a PERF_O_{MMAP,GROUP,INHERIT} enum, and if
204		- * O_MMAP is set, emit a warning if cpu < 0 and O_INHERIT is
205		- * set. Lets go for the minimal fix first tho.
206		- */
207		- evsel->attr.inherit = (cpus->map[cpu] >= 0) && inherit;
208	195
209	196	for (thread = 0; thread < threads->nr; thread++) {
210	197
...	...	@@ -253,7 +240,7 @@
253	240	};
254	241
255	242	int perf_evsel__open(struct perf_evsel evsel, struct cpu_map cpus,
256		- struct thread_map *threads, bool group, bool inherit)
	243	+ struct thread_map *threads, bool group)
257	244	{
258	245	if (cpus == NULL) {
259	246	/* Work around old compiler warnings about strict aliasing */
260	247
261	248
262	249
263	250
...	...	@@ -263,19 +250,19 @@
263	250	if (threads == NULL)
264	251	threads = &empty_thread_map.map;
265	252
266		- return __perf_evsel__open(evsel, cpus, threads, group, inherit);
	253	+ return __perf_evsel__open(evsel, cpus, threads, group);
267	254	}
268	255
269	256	int perf_evsel__open_per_cpu(struct perf_evsel *evsel,
270		- struct cpu_map *cpus, bool group, bool inherit)
	257	+ struct cpu_map *cpus, bool group)
271	258	{
272		- return __perf_evsel__open(evsel, cpus, &empty_thread_map.map, group, inherit);
	259	+ return __perf_evsel__open(evsel, cpus, &empty_thread_map.map, group);
273	260	}
274	261
275	262	int perf_evsel__open_per_thread(struct perf_evsel *evsel,
276		- struct thread_map *threads, bool group, bool inherit)
	263	+ struct thread_map *threads, bool group)
277	264	{
278		- return __perf_evsel__open(evsel, &empty_cpu_map.map, threads, group, inherit);
	265	+ return __perf_evsel__open(evsel, &empty_cpu_map.map, threads, group);
279	266	}
280	267
281	268	static int perf_event__parse_id_sample(const union perf_event *event, u64 type,
...	...	@@ -81,11 +81,11 @@
81	81	void perf_evsel__close_fd(struct perf_evsel *evsel, int ncpus, int nthreads);
82	82
83	83	int perf_evsel__open_per_cpu(struct perf_evsel *evsel,
84		- struct cpu_map *cpus, bool group, bool inherit);
	84	+ struct cpu_map *cpus, bool group);
85	85	int perf_evsel__open_per_thread(struct perf_evsel *evsel,
86		- struct thread_map *threads, bool group, bool inherit);
	86	+ struct thread_map *threads, bool group);
87	87	int perf_evsel__open(struct perf_evsel evsel, struct cpu_map cpus,
88		- struct thread_map *threads, bool group, bool inherit);
	88	+ struct thread_map *threads, bool group);
89	89
90	90	#define perf_evsel__match(evsel, t, c) \
91	91	(evsel->attr.type == PERF_TYPE_##t && \
...	...	@@ -498,11 +498,11 @@
498	498	struct cpu_map *cpus = NULL;
499	499	struct thread_map *threads = NULL;
500	500	PyObject pcpus = NULL, pthreads = NULL;
501		- int group = 0, overwrite = 0;
502		- static char *kwlist[] = {"cpus", "threads", "group", "overwrite", NULL, NULL};
	501	+ int group = 0, inherit = 0;
	502	+ static char *kwlist[] = {"cpus", "threads", "group", "inherit", NULL, NULL};
503	503
504	504	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "\|OOii", kwlist,
505		- &pcpus, &pthreads, &group, &overwrite))
	505	+ &pcpus, &pthreads, &group, &inherit))
506	506	return NULL;
507	507
508	508	if (pthreads != NULL)
...	...	@@ -511,7 +511,8 @@
511	511	if (pcpus != NULL)
512	512	cpus = ((struct pyrf_cpu_map *)pcpus)->cpus;
513	513
514		- if (perf_evsel__open(evsel, cpus, threads, group, overwrite) < 0) {
	514	+ evsel->attr.inherit = inherit;
	515	+ if (perf_evsel__open(evsel, cpus, threads, group) < 0) {
515	516	PyErr_SetFromErrno(PyExc_OSError);
516	517	return NULL;
517	518	}