sched/cputime: Rename vtime fields
The current "snapshot" based naming on vtime fields suggests we record
some past event but that's a low level picture of their actual purpose
which comes out blurry. The real point of these fields is to run a basic
state machine that tracks down cputime entry while switching between
contexts.
So lets reflect that with more meaningful names.
Tested-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1498756511-11714-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index ab68927..8c647530 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -683,10 +683,10 @@ static u64 vtime_delta(struct task_struct *tsk)
{
unsigned long now = READ_ONCE(jiffies);
- if (time_before(now, (unsigned long)tsk->vtime_snap))
+ if (time_before(now, (unsigned long)tsk->vtime_starttime))
return 0;
- return jiffies_to_nsecs(now - tsk->vtime_snap);
+ return jiffies_to_nsecs(now - tsk->vtime_starttime);
}
static u64 get_vtime_delta(struct task_struct *tsk)
@@ -701,10 +701,10 @@ static u64 get_vtime_delta(struct task_struct *tsk)
* elapsed time. Limit account_other_time to prevent rounding
* errors from causing elapsed vtime to go negative.
*/
- delta = jiffies_to_nsecs(now - tsk->vtime_snap);
+ delta = jiffies_to_nsecs(now - tsk->vtime_starttime);
other = account_other_time(delta);
- WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);
- tsk->vtime_snap = now;
+ WARN_ON_ONCE(tsk->vtime_state == VTIME_INACTIVE);
+ tsk->vtime_starttime = now;
return delta - other;
}
@@ -746,7 +746,7 @@ void vtime_guest_enter(struct task_struct *tsk)
{
/*
* The flags must be updated under the lock with
- * the vtime_snap flush and update.
+ * the vtime_starttime flush and update.
* That enforces a right ordering and update sequence
* synchronization against the reader (task_gtime())
* that can thus safely catch up with a tickless delta.
@@ -776,12 +776,12 @@ void vtime_account_idle(struct task_struct *tsk)
void arch_vtime_task_switch(struct task_struct *prev)
{
write_seqcount_begin(&prev->vtime_seqcount);
- prev->vtime_snap_whence = VTIME_INACTIVE;
+ prev->vtime_state = VTIME_INACTIVE;
write_seqcount_end(&prev->vtime_seqcount);
write_seqcount_begin(¤t->vtime_seqcount);
- current->vtime_snap_whence = VTIME_SYS;
- current->vtime_snap = jiffies;
+ current->vtime_state = VTIME_SYS;
+ current->vtime_starttime = jiffies;
write_seqcount_end(¤t->vtime_seqcount);
}
@@ -791,8 +791,8 @@ void vtime_init_idle(struct task_struct *t, int cpu)
local_irq_save(flags);
write_seqcount_begin(&t->vtime_seqcount);
- t->vtime_snap_whence = VTIME_SYS;
- t->vtime_snap = jiffies;
+ t->vtime_state = VTIME_SYS;
+ t->vtime_starttime = jiffies;
write_seqcount_end(&t->vtime_seqcount);
local_irq_restore(flags);
}
@@ -809,7 +809,7 @@ u64 task_gtime(struct task_struct *t)
seq = read_seqcount_begin(&t->vtime_seqcount);
gtime = t->gtime;
- if (t->vtime_snap_whence == VTIME_SYS && t->flags & PF_VCPU)
+ if (t->vtime_state == VTIME_SYS && t->flags & PF_VCPU)
gtime += vtime_delta(t);
} while (read_seqcount_retry(&t->vtime_seqcount, seq));
@@ -840,7 +840,7 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
*stime = t->stime;
/* Task is sleeping, nothing to add */
- if (t->vtime_snap_whence == VTIME_INACTIVE || is_idle_task(t))
+ if (t->vtime_state == VTIME_INACTIVE || is_idle_task(t))
continue;
delta = vtime_delta(t);
@@ -849,9 +849,9 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
* Task runs either in user or kernel space, add pending nohz time to
* the right place.
*/
- if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU)
+ if (t->vtime_state == VTIME_USER || t->flags & PF_VCPU)
*utime += delta;
- else if (t->vtime_snap_whence == VTIME_SYS)
+ else if (t->vtime_state == VTIME_SYS)
*stime += delta;
} while (read_seqcount_retry(&t->vtime_seqcount, seq));
}
