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.
Cc: Wanpeng Li <kernel...@gmail.com>
Cc: Rik van Riel <r...@redhat.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Luiz Capitulino <lcapitul...@redhat.com>
Signed-off-by: Frederic Weisbecker <fweis...@gmail.com>
---
include/linux/init_task.h | 4 ++--
include/linux/sched.h | 4 ++--
kernel/fork.c | 4 ++--
kernel/sched/cputime.c | 30 +++++++++++++++---------------
4 files changed, 21 insertions(+), 21 deletions(-)
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index e049526..3d53733 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -171,8 +171,8 @@ extern struct cred init_cred;
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
# define INIT_VTIME(tsk) \
.vtime_seqcount = SEQCNT_ZERO(tsk.vtime_seqcount), \
- .vtime_snap = 0, \
- .vtime_snap_whence = VTIME_SYS,
+ .vtime_starttime = 0, \
+ .vtime_state = VTIME_SYS,
#else
# define INIT_VTIME(tsk)
#endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1f0f427..22d2d9b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -689,7 +689,7 @@ struct task_struct {
struct prev_cputime prev_cputime;
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
seqcount_t vtime_seqcount;
- unsigned long long vtime_snap;
+ unsigned long long vtime_starttime;
enum {
/* Task is sleeping or running in a CPU with VTIME inactive: */
VTIME_INACTIVE = 0,
@@ -697,7 +697,7 @@ struct task_struct {
VTIME_USER,
/* Task runs in kernelspace in a CPU with VTIME active: */
VTIME_SYS,
- } vtime_snap_whence;
+ } vtime_state;
#endif
#ifdef CONFIG_NO_HZ_FULL
diff --git a/kernel/fork.c b/kernel/fork.c
index e53770d..83c4f9b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1638,8 +1638,8 @@ static __latent_entropy struct task_struct *copy_process(
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
seqcount_init(&p->vtime_seqcount);
- p->vtime_snap = 0;
- p->vtime_snap_whence = VTIME_INACTIVE;
+ p->vtime_starttime = 0;
+ p->vtime_state = VTIME_INACTIVE;
#endif
#if defined(SPLIT_RSS_COUNTING)
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index db7ef10..6b152c2 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));
}
--
2.7.4
