Record idle as a VTIME state instead of guessing it from VTIME_SYS and is_idle_task(). This is going to simplify the cputime read side especially as its state machine is going to further expand in order to fully support kcpustat on nohz_full.
Signed-off-by: Frederic Weisbecker <frede...@kernel.org> Cc: Yauheni Kaliuta <yauheni.kali...@redhat.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Rik van Riel <r...@redhat.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Wanpeng Li <wanpen...@tencent.com> Cc: Ingo Molnar <mi...@kernel.org> --- include/linux/sched.h | 6 ++++-- kernel/sched/cputime.c | 13 ++++++++----- 2 files changed, 12 insertions(+), 7 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 9f56880..6d13938 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -265,10 +265,12 @@ struct task_cputime { enum vtime_state { /* Task is sleeping or running in a CPU with VTIME inactive: */ VTIME_INACTIVE = 0, - /* Task runs in userspace in a CPU with VTIME active: */ - VTIME_USER, + /* Task is idle */ + VTIME_IDLE, /* Task runs in kernelspace in a CPU with VTIME active: */ VTIME_SYS, + /* Task runs in userspace in a CPU with VTIME active: */ + VTIME_USER, }; struct vtime { diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 6ac27687..a9f42cc 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -812,7 +812,7 @@ void vtime_task_switch_generic(struct task_struct *prev) struct vtime *vtime = &prev->vtime; write_seqcount_begin(&vtime->seqcount); - if (is_idle_task(prev)) + if (vtime->state == VTIME_IDLE) vtime_account_idle(prev); else __vtime_account_kernel(prev, vtime); @@ -823,7 +823,10 @@ void vtime_task_switch_generic(struct task_struct *prev) vtime = ¤t->vtime; write_seqcount_begin(&vtime->seqcount); - vtime->state = VTIME_SYS; + if (is_idle_task(current)) + vtime->state = VTIME_IDLE; + else + vtime->state = VTIME_SYS; vtime->starttime = sched_clock(); vtime->cpu = smp_processor_id(); write_seqcount_end(&vtime->seqcount); @@ -836,7 +839,7 @@ void vtime_init_idle(struct task_struct *t, int cpu) local_irq_save(flags); write_seqcount_begin(&vtime->seqcount); - vtime->state = VTIME_SYS; + vtime->state = VTIME_IDLE; vtime->starttime = sched_clock(); vtime->cpu = cpu; write_seqcount_end(&vtime->seqcount); @@ -887,8 +890,8 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime) *utime = t->utime; *stime = t->stime; - /* Task is sleeping, nothing to add */ - if (vtime->state == VTIME_INACTIVE || is_idle_task(t)) + /* Task is sleeping or idle, nothing to add */ + if (vtime->state < VTIME_SYS) continue; delta = vtime_delta(vtime); -- 2.7.4