1)Iterate thru 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 <[email protected]>
CC: Konstantin Khorenko <[email protected]>
CC: Ben Segall <[email protected]>
CC: Paul Turner <[email protected]>
CC: Srikar Dronamraju <[email protected]>
CC: Mike Galbraith <[email protected]>
CC: Peter Zijlstra <[email protected]>
CC: Ingo Molnar <[email protected]>
---
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 {
* Kirill Tkhai <[email protected]> [2014-06-25 12:19:55]:
>
> 1)Iterate thru 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 <[email protected]>
> CC: Konstantin Khorenko <[email protected]>
> CC: Ben Segall <[email protected]>
> CC: Paul Turner <[email protected]>
> CC: Srikar Dronamraju <[email protected]>
> CC: Mike Galbraith <[email protected]>
> CC: Peter Zijlstra <[email protected]>
> CC: Ingo Molnar <[email protected]>
> ---
Reviewed-by: Srikar Dronamraju <[email protected]>
--
Thanks and Regards
Srikar Dronamraju
Commit-ID: b728ca06029d085a1585c1926610f26de93b9146
Gitweb: http://git.kernel.org/tip/b728ca06029d085a1585c1926610f26de93b9146
Author: Kirill Tkhai <[email protected]>
AuthorDate: Wed, 25 Jun 2014 12:19:55 +0400
Committer: Ingo Molnar <[email protected]>
CommitDate: Sat, 5 Jul 2014 11:17:45 +0200
sched: Rework check_for_tasks()
1) Iterate thru 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 <[email protected]>
Reviewed-by: Srikar Dronamraju <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Ben Segall <[email protected]>
Cc: Fabian Frederick <[email protected]>
Cc: Gautham R. Shenoy <[email protected]>
Cc: Konstantin Khorenko <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Michael wang <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Srivatsa S. Bhat <[email protected]>
Cc: Todd E Brandt <[email protected]>
Cc: Toshi Kani <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/1403684395.3462.44.camel@tkhai
Signed-off-by: Ingo Molnar <[email protected]>
---
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 {