Messages in this thread Patch in this message | | | Subject | [PATCH v3 1/3] posix_timers: do not account group_exec_runtime for dying autoreaped tasks | From | Olivier Langlois <> | Date | Mon, 29 Apr 2013 14:04:09 -0400 |
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Forbids the cputimer to drift ahead of its process clock by blocking its update when a tick occurs while a autoreaping task is currently in do_exit() between the call to release_task() and its final call to schedule().
Any task stats update after having called release_task() will be lost because they are added to the global process stats located in the signal struct from release_task().
Signed-off-by: Olivier Langlois <olivier@trillion01.com> --- kernel/sched/fair.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7a33e59..52d7b10 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -708,7 +708,15 @@ static void update_curr(struct cfs_rq *cfs_rq) trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); cpuacct_charge(curtask, delta_exec); - account_group_exec_runtime(curtask, delta_exec); + /* + * Do not update the cputimer if the task is already released by + * release_task(). + * + * it would preferable to defer the autoreap release_task + * after the last context switch but harder to do. + */ + if (likely(curtask->sighand)) + account_group_exec_runtime(curtask, delta_exec); } account_cfs_rq_runtime(cfs_rq, delta_exec); -- 1.8.2.1
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