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authorFrederic Weisbecker <fweisbec@gmail.com>2012-12-16 20:00:34 +0100
committerFrederic Weisbecker <fweisbec@gmail.com>2013-01-27 20:35:47 +0100
commit6a61671bb2f3a1bd12cd17b8fca811a624782632 (patch)
tree0afc2915fb7e517472710a49a524510322dd5baa /kernel/sched/core.c
parentc11f11fcbdb5be790c565aed46411486a7586afc (diff)
downloadlinaro-lsk-6a61671bb2f3a1bd12cd17b8fca811a624782632.tar.gz
cputime: Safely read cputime of full dynticks CPUs
While remotely reading the cputime of a task running in a full dynticks CPU, the values stored in utime/stime fields of struct task_struct may be stale. Its values may be those of the last kernel <-> user transition time snapshot and we need to add the tickless time spent since this snapshot. To fix this, flush the cputime of the dynticks CPUs on kernel <-> user transition and record the time / context where we did this. Then on top of this snapshot and the current time, perform the fixup on the reader side from task_times() accessors. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> [fixed kvm module related build errors] Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
Diffstat (limited to 'kernel/sched/core.c')
-rw-r--r--kernel/sched/core.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 257002c13bb..261022d7e79 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4666,6 +4666,7 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
*/
idle->sched_class = &idle_sched_class;
ftrace_graph_init_idle_task(idle, cpu);
+ vtime_init_idle(idle);
#if defined(CONFIG_SMP)
sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
#endif