sched/cputime: Clarify vtime symbols and document them

VTIME_SLEEPING state happens either when:

1) The task is sleeping and no tickless delta is to be added on the task
   cputime stats.
2) The CPU isn't running vtime at all, so the same properties of 1) applies.

Lets rename the vtime symbol to reflect both states.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1447948054-28668-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f425aac633177e3723fcebafc8b2fe6d4063e465..3533168fe7d1f188b0360e59e8baa5ba49bafab8 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1522,8 +1522,11 @@ struct task_struct {
        seqlock_t vtime_seqlock;
        unsigned long long vtime_snap;
        enum {
-               VTIME_SLEEPING = 0,
+               /* 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 runs in kernelspace in a CPU with VTIME active */
                VTIME_SYS,
        } vtime_snap_whence;
 #endif

diff --git a/kernel/fork.c b/kernel/fork.c
index f97f2c449f5cf556ea6c54cb4aec6e894dd8bab5..c0a13706b1a75f09c47f8d86d0a1f2d80d5c8d11 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1350,7 +1350,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
        seqlock_init(&p->vtime_seqlock);
        p->vtime_snap = 0;
-       p->vtime_snap_whence = VTIME_SLEEPING;
+       p->vtime_snap_whence = VTIME_INACTIVE;
 #endif
 
 #if defined(SPLIT_RSS_COUNTING)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 1128d4ba6c552822143e9b1cea0f12d7e6aa8d57..4a18a6ed7723fe57552f67a84686b8a9ab9bcafd 100644 (file)
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -680,7 +680,7 @@ static cputime_t get_vtime_delta(struct task_struct *tsk)
 {
        unsigned long long delta = vtime_delta(tsk);
 
-       WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
+       WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);
        tsk->vtime_snap += delta;
 
        /* CHECKME: always safe to convert nsecs to cputime? */
@@ -764,7 +764,7 @@ void vtime_account_idle(struct task_struct *tsk)
 void arch_vtime_task_switch(struct task_struct *prev)
 {
        write_seqlock(&prev->vtime_seqlock);
-       prev->vtime_snap_whence = VTIME_SLEEPING;
+       prev->vtime_snap_whence = VTIME_INACTIVE;
        write_sequnlock(&prev->vtime_seqlock);
 
        write_seqlock(&current->vtime_seqlock);
@@ -829,7 +829,7 @@ fetch_task_cputime(struct task_struct *t,
                        *s_dst = *s_src;
 
                /* Task is sleeping, nothing to add */
-               if (t->vtime_snap_whence == VTIME_SLEEPING ||
+               if (t->vtime_snap_whence == VTIME_INACTIVE ||
                    is_idle_task(t))
                        continue;