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Subject[PATCH] perf: change event inheritance logic in stat and record
  By default, event inheritance across fork and pthread_create was
on but the -i option of stat and record, which enabled inheritance,
led to believe it was off by default.

This patch fixes this logic by inverting the meaning of the -i option.
By default inheritance is on whether you attach to a process (-p), a
thread (-t) or start a process. If you pass -i, then you turn off
inheritance. Turning off inheritance if you don't need it, helps
limit perf resource usage as well.

The patch also fixes perf stat -t xxxx and perf record -t xxxx
which did not start the counters.

Signed-off-by: Stephane Eranian <eranian@google.com>
--
Documentation/perf-record.txt | 4 ++--
Documentation/perf-stat.txt | 4 ++--
builtin-record.c | 12 ++++++------
builtin-stat.c | 10 +++++-----
4 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 020d871..34e255f 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -69,8 +69,8 @@ OPTIONS
Output file name.

-i::
---inherit::
- Child tasks inherit counters.
+--no-inherit::
+ Child tasks do not inherit counters.
-F::
--freq=::
Profile at this frequency.
diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 484080d..2cab8e8 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -31,8 +31,8 @@ OPTIONS
hexadecimal event descriptor.

-i::
---inherit::
- child tasks inherit counters
+--no-inherit::
+ child tasks do not inherit counters
-p::
--pid=<pid>::
stat events on existing pid
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 6b77b28..0f467cf 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -54,7 +54,7 @@ static pid_t target_tid = -1;
static pid_t *all_tids = NULL;
static int thread_num = 0;
static pid_t child_pid = -1;
-static bool inherit = true;
+static bool no_inherit = false;
static enum write_mode_t write_mode = WRITE_FORCE;
static bool call_graph = false;
static bool inherit_stat = false;
@@ -298,8 +298,8 @@ static void create_counter(int counter, int cpu)

attr->mmap = track;
attr->comm = track;
- attr->inherit = inherit;
- if (target_pid == -1 && !system_wide) {
+ attr->inherit = !no_inherit;
+ if (target_pid == -1 && target_tid == -1 && !system_wide) {
attr->disabled = 1;
attr->enable_on_exec = 1;
}
@@ -641,7 +641,7 @@ static int __cmd_record(int argc, const char **argv)
close(child_ready_pipe[0]);
}

- if ((!system_wide && !inherit) || profile_cpu != -1) {
+ if ((!system_wide && no_inherit) || profile_cpu != -1) {
open_counters(profile_cpu);
} else {
nr_cpus = read_cpu_map();
@@ -821,8 +821,8 @@ static const struct option options[] = {
"event period to sample"),
OPT_STRING('o', "output", &output_name, "file",
"output file name"),
- OPT_BOOLEAN('i', "inherit", &inherit,
- "child tasks inherit counters"),
+ OPT_BOOLEAN('i', "no-inherit", &no_inherit,
+ "child tasks do not inherit counters"),
OPT_INTEGER('F', "freq", &user_freq,
"profile at this frequency"),
OPT_INTEGER('m', "mmap-pages", &mmap_pages,
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index e619ac8..ff8c413 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -72,7 +72,7 @@ static unsigned int nr_cpus = 0;
static int run_idx = 0;

static int run_count = 1;
-static bool inherit = true;
+static bool no_inherit = false;
static bool scale = true;
static pid_t target_pid = -1;
static pid_t target_tid = -1;
@@ -167,8 +167,8 @@ static int create_perf_stat_counter(int counter)
++ncreated;
}
} else {
- attr->inherit = inherit;
- if (target_pid == -1) {
+ attr->inherit = !no_inherit;
+ if (target_pid == -1 && target_tid == -1) {
attr->disabled = 1;
attr->enable_on_exec = 1;
}
@@ -518,8 +518,8 @@ static const struct option options[] = {
OPT_CALLBACK('e', "event", NULL, "event",
"event selector. use 'perf list' to list available events",
parse_events),
- OPT_BOOLEAN('i', "inherit", &inherit,
- "child tasks inherit counters"),
+ OPT_BOOLEAN('i', "no-inherit", &no_inherit,
+ "child tasks do not inherit counters"),
OPT_INTEGER('p', "pid", &target_pid,
"stat events on existing process id"),
OPT_INTEGER('t', "tid", &target_tid,

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