[PATCH] perf evsel: Fix use of inherit

From: Arnaldo Carvalho de Melo
Date: Thu Apr 14 2011 - 10:20:14 EST

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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@xxxxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Tom Zanussi <tzanussi@xxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-c9vd0a96jgm7nltt5cala44x@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-record.c | 7 +++++--
tools/perf/builtin-stat.c | 7 ++++---
tools/perf/builtin-test.c | 10 +++++-----
tools/perf/builtin-top.c | 3 ++-
tools/perf/util/evlist.c | 14 ++++++++++----
tools/perf/util/evsel.c | 27 +++++++--------------------
tools/perf/util/evsel.h | 6 +++---
tools/perf/util/python.c | 9 +++++----
8 files changed, 41 insertions(+), 42 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 17d1dcb..4165382 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -163,6 +163,7 @@ static void config_attr(struct perf_evsel *evsel, struct perf_evlist *evlist)
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 @@ static void open_counters(struct perf_evlist *evlist)
{
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 @@ 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, 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) {
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index e2109f9..03f0e45 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -167,16 +167,17 @@ static int create_perf_stat_counter(struct perf_evsel *evsel)
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);
}

/*
diff --git a/tools/perf/builtin-test.c b/tools/perf/builtin-test.c
index 1b2106c..11e3c84 100644
--- a/tools/perf/builtin-test.c
+++ b/tools/perf/builtin-test.c
@@ -290,7 +290,7 @@ static int test__open_syscall_event(void)
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 @@ static int test__open_syscall_event(void)
}

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 @@ static int test__open_syscall_event_on_all_cpus(void)
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 @@ static int test__open_syscall_event_on_all_cpus(void)
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 @@ static int test__basic_mmap(void)

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));
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index fc1273e..7e3d6e3 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -845,9 +845,10 @@ static void start_counters(struct perf_evlist *evlist)
}

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) {
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index d852cef..45da8d1 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -12,6 +12,7 @@
#include "evlist.h"
#include "evsel.h"
#include "util.h"
+#include "debug.h"

#include <sys/mman.h>

@@ -250,15 +251,19 @@ int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
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 @@ int perf_evlist__mmap(struct perf_evlist *evlist, int pages, bool overwrite)
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) &&
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 662596a..d6fd59b 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -175,7 +175,7 @@ int __perf_evsel__read(struct perf_evsel *evsel,
}

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 @@ static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,

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 @@ static struct {
};

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 @@ int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
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,
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 6710ab5..f79bb2c 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -81,11 +81,11 @@ void perf_evsel__free_id(struct perf_evsel *evsel);
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 && \
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index a9f2d7e..f5e3845 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -498,11 +498,11 @@ static PyObject *pyrf_evsel__open(struct pyrf_evsel *pevsel,
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 @@ static PyObject *pyrf_evsel__open(struct pyrf_evsel *pevsel,
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;
}
--
1.7.1

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