From eef6cbf5844c620d9db9be99e4908cdf92492fb9 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 19 Dec 2008 10:20:42 +0100
Subject: [PATCH] perfcounters: pull inherited counters
Change counter inheritance from a 'push' to a 'pull' model: instead of
child tasks pushing their final counts to the parent, reuse the wait4
infrastructure to pull counters as child tasks are exit-processed,
much like how cutime/cstime is collected.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/init_task.h | 9 +++++++++
kernel/exit.c | 21 +++++++++------------
2 files changed, 18 insertions(+), 12 deletions(-)
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 23fd8909b9e5..54fa2fa2c8e4 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -113,6 +113,14 @@ extern struct group_info init_groups;
# define CAP_INIT_BSET CAP_INIT_EFF_SET
#endif
+#ifdef CONFIG_PERF_COUNTERS
+# define INIT_PERF_COUNTERS(tsk) \
+ .perf_counter_ctx.counter_list = \
+ LIST_HEAD_INIT(tsk.perf_counter_ctx.counter_list),
+#else
+# define INIT_PERF_COUNTERS(tsk)
+#endif
+
/*
* INIT_TASK is used to set up the first task table, touch at
* your own risk!. Base=0, limit=0x1fffff (=2MB)
@@ -180,6 +188,7 @@ extern struct group_info init_groups;
INIT_IDS \
INIT_TRACE_IRQFLAGS \
INIT_LOCKDEP \
+ INIT_PERF_COUNTERS(tsk) \
}
diff --git a/kernel/exit.c b/kernel/exit.c
index 244edfd96865..101b7eeff44c 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -153,6 +153,9 @@ static void delayed_put_task_struct(struct rcu_head *rhp)
{
struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
+#ifdef CONFIG_PERF_COUNTERS
+ WARN_ON_ONCE(!list_empty(&tsk->perf_counter_ctx.counter_list));
+#endif
trace_sched_process_free(tsk);
put_task_struct(tsk);
}
@@ -922,12 +925,6 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
forget_original_parent(tsk);
exit_task_namespaces(tsk);
- /*
- * Flush inherited counters to the parent - before the parent
- * gets woken up by child-exit notifications.
- */
- perf_counter_exit_task(tsk);
-
write_lock_irq(&tasklist_lock);
if (group_dead)
kill_orphaned_pgrp(tsk->group_leader, NULL);
@@ -1122,12 +1119,6 @@ NORET_TYPE void do_exit(long code)
if (tsk->splice_pipe)
__free_pipe_info(tsk->splice_pipe);
- /*
- * These must happen late, after the PID is not
- * hashed anymore, but still at a point that may sleep:
- */
- perf_counter_exit_task(tsk);
-
preempt_disable();
/* causes final put_task_struct in finish_task_switch(). */
tsk->state = TASK_DEAD;
@@ -1371,6 +1362,12 @@ static int wait_task_zombie(struct task_struct *p, int options,
*/
read_unlock(&tasklist_lock);
+ /*
+ * Flush inherited counters to the parent - before the parent
+ * gets woken up by child-exit notifications.
+ */
+ perf_counter_exit_task(p);
+
retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
status = (p->signal->flags & SIGNAL_GROUP_EXIT)
? p->signal->group_exit_code : p->exit_code;
--
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