[PATCH 26/32] nohz/cpuset: Flush cputime on threads in nohz cpusets when waiting leader

Frederic Weisbecker
2011-08-15T15:54:11Z

When we wait for a zombie task, flush the cputimes on nohz cpusets
in case we are waiting for a group leader that has threads running
in nohz CPUs. This way thread_group_times() doesn't report stale
values.

<doubts>
If I understood well the code, by the time we call that thread_group_times(),
we may have childs that are still running, so this is necessary.
But I need to check deeper.
</doubts>

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Anton Blanchard <anton@au1.ibm.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Pepper <lnxninja@linux.vnet.ibm.com>
---
kernel/exit.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index f2b321b..43fb9ac 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -51,6 +51,7 @@
#include <trace/events/sched.h>
#include <linux/hw_breakpoint.h>
#include <linux/oom.h>
+#include <linux/cpuset.h>

#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -1262,6 +1263,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
* group, which consolidates times for all threads in the
* group including the group leader.
*/
+ cpuset_nohz_flush_cputimes();
thread_group_times(p, &tgutime, &tgstime);
spin_lock_irq(&p->real_parent->sighand->siglock);
psig = p->real_parent->signal;
--
1.7.5.4