From 9d7fb04276481c59610983362d8e023d262b58ca Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 30 Jun 2015 11:30:54 +0200 Subject: sched/cputime: Guarantee stime + utime == rtime While the current code guarantees monotonicity for stime and utime independently of one another, it does not guarantee that the sum of both is equal to the total time we started out with. This confuses things (and peoples) who look at this sum, like top, and will report >100% usage followed by a matching period of 0%. Rework the code to provide both individual monotonicity and a coherent sum. Suggested-by: Fredrik Markstrom Reported-by: Fredrik Markstrom Tested-by: Fredrik Markstrom Signed-off-by: Peter Zijlstra (Intel) Cc: Frederic Weisbecker Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Rik van Riel Cc: Stanislaw Gruszka Cc: Thomas Gleixner Cc: jason.low2@hp.com Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- include/linux/init_task.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include/linux/init_task.h') diff --git a/include/linux/init_task.h b/include/linux/init_task.h index e8493fee8160..d0b380ee7d67 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -32,6 +32,14 @@ extern struct fs_struct init_fs; #define INIT_CPUSET_SEQ(tsk) #endif +#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE +#define INIT_PREV_CPUTIME(x) .prev_cputime = { \ + .lock = __RAW_SPIN_LOCK_UNLOCKED(x.prev_cputime.lock), \ +}, +#else +#define INIT_PREV_CPUTIME(x) +#endif + #define INIT_SIGNALS(sig) { \ .nr_threads = 1, \ .thread_head = LIST_HEAD_INIT(init_task.thread_node), \ @@ -46,6 +54,7 @@ extern struct fs_struct init_fs; .cputime_atomic = INIT_CPUTIME_ATOMIC, \ .running = 0, \ }, \ + INIT_PREV_CPUTIME(sig) \ .cred_guard_mutex = \ __MUTEX_INITIALIZER(sig.cred_guard_mutex), \ } @@ -246,6 +255,7 @@ extern struct task_group root_task_group; INIT_TASK_RCU_TASKS(tsk) \ INIT_CPUSET_SEQ(tsk) \ INIT_RT_MUTEXES(tsk) \ + INIT_PREV_CPUTIME(tsk) \ INIT_VTIME(tsk) \ INIT_NUMA_BALANCING(tsk) \ INIT_KASAN(tsk) \ -- cgit v1.2.3