From: Kirill Tkhai <ktkhai@parallels.com>
To: <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>, <tkhai@yandex.ru>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
"Mike Galbraith" <umgwanakikbuti@gmail.com>,
<khorenko@parallels.com>, Ben Segall <bsegall@google.com>,
Paul Turner <pjt@google.com>
Subject: [PATCH v2 3/3] sched: Rework check_for_tasks()
Date: Tue, 24 Jun 2014 11:54:04 +0400 [thread overview]
Message-ID: <1403596444.3462.28.camel@tkhai> (raw)
In-Reply-To: <20140624074148.8738.57690.stgit@tkhai>
1)Iterate throw all of threads in the system.
Check for all threads, not only for group leaders.
2)Check for p->on_rq instead of p->state and cputime.
Preempted task in !TASK_RUNNING state OR just
created task may be queued, that we want to be
reported too.
3)Use read_lock() instead of write_lock().
This function does not change any structures, and
read_lock() is enough.
Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
CC: Konstantin Khorenko <khorenko@parallels.com>
CC: Ben Segall <bsegall@google.com>
CC: Paul Turner <pjt@google.com>
CC: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
CC: Mike Galbraith <umgwanakikbuti@gmail.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Ingo Molnar <mingo@kernel.org>
---
kernel/cpu.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index a343bde..81e2a38 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -274,21 +274,28 @@ void clear_tasks_mm_cpumask(int cpu)
rcu_read_unlock();
}
-static inline void check_for_tasks(int cpu)
+static inline void check_for_tasks(int dead_cpu)
{
- struct task_struct *p;
- cputime_t utime, stime;
+ struct task_struct *g, *p;
- write_lock_irq(&tasklist_lock);
- for_each_process(p) {
- task_cputime(p, &utime, &stime);
- if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
- (utime || stime))
- pr_warn("Task %s (pid = %d) is on cpu %d (state = %ld, flags = %x)\n",
- p->comm, task_pid_nr(p), cpu,
- p->state, p->flags);
- }
- write_unlock_irq(&tasklist_lock);
+ read_lock_irq(&tasklist_lock);
+ do_each_thread(g, p) {
+ if (!p->on_rq)
+ continue;
+ /*
+ * We do the check with unlocked task_rq(p)->lock.
+ * Order the reading to do not warn about a task,
+ * which was running on this cpu in the past, and
+ * it's just been woken on another cpu.
+ */
+ rmb();
+ if (task_cpu(p) != dead_cpu)
+ continue;
+
+ pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
+ p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
+ } while_each_thread(g, p);
+ read_unlock_irq(&tasklist_lock);
}
struct take_cpu_down_param {
prev parent reply other threads:[~2014-06-24 7:54 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20140624074148.8738.57690.stgit@tkhai>
2014-06-24 7:53 ` [PATCH v2 1/3] sched/fair: Disable runtime_enabled on dying rq Kirill Tkhai
2014-06-24 17:03 ` bsegall
2014-06-24 19:01 ` Kirill Tkhai
2014-06-24 19:13 ` bsegall
2014-06-24 19:26 ` Kirill Tkhai
2014-06-25 7:53 ` Kirill Tkhai
2014-06-25 8:03 ` Kirill Tkhai
2014-06-25 16:52 ` bsegall
2014-06-25 17:31 ` Kirill Tkhai
2014-06-25 17:40 ` bsegall
2014-06-25 17:44 ` Kirill Tkhai
2014-06-26 11:08 ` Srikar Dronamraju
2014-06-24 7:53 ` [PATCH v2 2/3] sched/rt: __disable_runtime: Enqueue just unthrottled rt_rq back on the stack Kirill Tkhai
2014-06-24 7:54 ` Kirill Tkhai [this message]
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