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>
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 @@
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) &&
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 @@
}
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,
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__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 @@
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;
}