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sched/cputime: Move the vtime task fields to their own struct
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We are about to add vtime accumulation fields to the task struct. Let's
avoid more bloatification and gather vtime information to their own
struct.

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/1498756511-11714-5-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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fweisbec authored and Ingo Molnar committed Jul 5, 2017
1 parent 60a9ce5 commit bac5b6b
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Showing 4 changed files with 86 additions and 64 deletions.
6 changes: 3 additions & 3 deletions include/linux/init_task.h
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Original file line number Diff line number Diff line change
Expand Up @@ -170,9 +170,9 @@ extern struct cred init_cred;

#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
# define INIT_VTIME(tsk) \
.vtime_seqcount = SEQCNT_ZERO(tsk.vtime_seqcount), \
.vtime_starttime = 0, \
.vtime_state = VTIME_SYS,
.vtime.seqcount = SEQCNT_ZERO(tsk.vtime.seqcount), \
.vtime.starttime = 0, \
.vtime.state = VTIME_SYS,
#else
# define INIT_VTIME(tsk)
#endif
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26 changes: 16 additions & 10 deletions include/linux/sched.h
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Expand Up @@ -223,6 +223,21 @@ struct task_cputime {
#define prof_exp stime
#define sched_exp sum_exec_runtime

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 runs in kernelspace in a CPU with VTIME active: */
VTIME_SYS,
};

struct vtime {
seqcount_t seqcount;
unsigned long long starttime;
enum vtime_state state;
};

struct sched_info {
#ifdef CONFIG_SCHED_INFO
/* Cumulative counters: */
Expand Down Expand Up @@ -688,16 +703,7 @@ struct task_struct {
u64 gtime;
struct prev_cputime prev_cputime;
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
seqcount_t vtime_seqcount;
unsigned long long vtime_starttime;
enum {
/* 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_state;
struct vtime vtime;
#endif

#ifdef CONFIG_NO_HZ_FULL
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6 changes: 3 additions & 3 deletions kernel/fork.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1637,9 +1637,9 @@ static __latent_entropy struct task_struct *copy_process(
prev_cputime_init(&p->prev_cputime);

#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
seqcount_init(&p->vtime_seqcount);
p->vtime_starttime = 0;
p->vtime_state = VTIME_INACTIVE;
seqcount_init(&p->vtime.seqcount);
p->vtime.starttime = 0;
p->vtime.state = VTIME_INACTIVE;
#endif

#if defined(SPLIT_RSS_COUNTING)
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112 changes: 64 additions & 48 deletions kernel/sched/cputime.c
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Original file line number Diff line number Diff line change
Expand Up @@ -679,17 +679,17 @@ void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
#endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */

#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
static u64 vtime_delta(struct task_struct *tsk)
static u64 vtime_delta(struct vtime *vtime)
{
unsigned long now = READ_ONCE(jiffies);

if (time_before(now, (unsigned long)tsk->vtime_starttime))
if (time_before(now, (unsigned long)vtime->starttime))
return 0;

return jiffies_to_nsecs(now - tsk->vtime_starttime);
return jiffies_to_nsecs(now - vtime->starttime);
}

static u64 get_vtime_delta(struct task_struct *tsk)
static u64 get_vtime_delta(struct vtime *vtime)
{
unsigned long now = READ_ONCE(jiffies);
u64 delta, other;
Expand All @@ -701,118 +701,133 @@ 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_starttime);
delta = jiffies_to_nsecs(now - vtime->starttime);
other = account_other_time(delta);
WARN_ON_ONCE(tsk->vtime_state == VTIME_INACTIVE);
tsk->vtime_starttime = now;
WARN_ON_ONCE(vtime->state == VTIME_INACTIVE);
vtime->starttime = now;

return delta - other;
}

static void __vtime_account_system(struct task_struct *tsk)
{
account_system_time(tsk, irq_count(), get_vtime_delta(tsk));
account_system_time(tsk, irq_count(), get_vtime_delta(&tsk->vtime));
}

void vtime_account_system(struct task_struct *tsk)
{
if (!vtime_delta(tsk))
struct vtime *vtime = &tsk->vtime;

if (!vtime_delta(vtime))
return;

write_seqcount_begin(&tsk->vtime_seqcount);
write_seqcount_begin(&vtime->seqcount);
__vtime_account_system(tsk);
write_seqcount_end(&tsk->vtime_seqcount);
write_seqcount_end(&vtime->seqcount);
}

void vtime_user_enter(struct task_struct *tsk)
{
write_seqcount_begin(&tsk->vtime_seqcount);
if (vtime_delta(tsk))
struct vtime *vtime = &tsk->vtime;

write_seqcount_begin(&vtime->seqcount);
if (vtime_delta(vtime))
__vtime_account_system(tsk);
tsk->vtime_snap_whence = VTIME_USER;
write_seqcount_end(&tsk->vtime_seqcount);
vtime->state = VTIME_USER;
write_seqcount_end(&vtime->seqcount);
}

void vtime_user_exit(struct task_struct *tsk)
{
write_seqcount_begin(&tsk->vtime_seqcount);
if (vtime_delta(tsk))
account_user_time(tsk, get_vtime_delta(tsk));
tsk->vtime_snap_whence = VTIME_SYS;
write_seqcount_end(&tsk->vtime_seqcount);
struct vtime *vtime = &tsk->vtime;

write_seqcount_begin(&vtime->seqcount);
if (vtime_delta(vtime))
account_user_time(tsk, get_vtime_delta(vtime));
vtime->state = VTIME_SYS;
write_seqcount_end(&vtime->seqcount);
}

void vtime_guest_enter(struct task_struct *tsk)
{
struct vtime *vtime = &tsk->vtime;
/*
* The flags must be updated under the lock with
* 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.
*/
write_seqcount_begin(&tsk->vtime_seqcount);
if (vtime_delta(tsk))
write_seqcount_begin(&vtime->seqcount);
if (vtime_delta(vtime))
__vtime_account_system(tsk);
current->flags |= PF_VCPU;
write_seqcount_end(&tsk->vtime_seqcount);
write_seqcount_end(&vtime->seqcount);
}
EXPORT_SYMBOL_GPL(vtime_guest_enter);

void vtime_guest_exit(struct task_struct *tsk)
{
write_seqcount_begin(&tsk->vtime_seqcount);
struct vtime *vtime = &tsk->vtime;

write_seqcount_begin(&vtime->seqcount);
__vtime_account_system(tsk);
current->flags &= ~PF_VCPU;
write_seqcount_end(&tsk->vtime_seqcount);
write_seqcount_end(&vtime->seqcount);
}
EXPORT_SYMBOL_GPL(vtime_guest_exit);

void vtime_account_idle(struct task_struct *tsk)
{
account_idle_time(get_vtime_delta(tsk));
account_idle_time(get_vtime_delta(&tsk->vtime));
}

void arch_vtime_task_switch(struct task_struct *prev)
{
write_seqcount_begin(&prev->vtime_seqcount);
prev->vtime_state = VTIME_INACTIVE;
write_seqcount_end(&prev->vtime_seqcount);
struct vtime *vtime = &prev->vtime;

write_seqcount_begin(&current->vtime_seqcount);
current->vtime_state = VTIME_SYS;
current->vtime_starttime = jiffies;
write_seqcount_end(&current->vtime_seqcount);
write_seqcount_begin(&vtime->seqcount);
vtime->state = VTIME_INACTIVE;
write_seqcount_end(&vtime->seqcount);

vtime = &current->vtime;

write_seqcount_begin(&vtime->seqcount);
vtime->state = VTIME_SYS;
vtime->starttime = jiffies;
write_seqcount_end(&vtime->seqcount);
}

void vtime_init_idle(struct task_struct *t, int cpu)
{
struct vtime *vtime = &t->vtime;
unsigned long flags;

local_irq_save(flags);
write_seqcount_begin(&t->vtime_seqcount);
t->vtime_state = VTIME_SYS;
t->vtime_starttime = jiffies;
write_seqcount_end(&t->vtime_seqcount);
write_seqcount_begin(&vtime->seqcount);
vtime->state = VTIME_SYS;
vtime->starttime = jiffies;
write_seqcount_end(&vtime->seqcount);
local_irq_restore(flags);
}

u64 task_gtime(struct task_struct *t)
{
struct vtime *vtime = &t->vtime;
unsigned int seq;
u64 gtime;

if (!vtime_accounting_enabled())
return t->gtime;

do {
seq = read_seqcount_begin(&t->vtime_seqcount);
seq = read_seqcount_begin(&vtime->seqcount);

gtime = t->gtime;
if (t->vtime_state == VTIME_SYS && t->flags & PF_VCPU)
gtime += vtime_delta(t);
if (vtime->state == VTIME_SYS && t->flags & PF_VCPU)
gtime += vtime_delta(vtime);

} while (read_seqcount_retry(&t->vtime_seqcount, seq));
} while (read_seqcount_retry(&vtime->seqcount, seq));

return gtime;
}
Expand All @@ -824,8 +839,9 @@ u64 task_gtime(struct task_struct *t)
*/
void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
{
u64 delta;
struct vtime *vtime = &t->vtime;
unsigned int seq;
u64 delta;

if (!vtime_accounting_enabled()) {
*utime = t->utime;
Expand All @@ -834,25 +850,25 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
}

do {
seq = read_seqcount_begin(&t->vtime_seqcount);
seq = read_seqcount_begin(&vtime->seqcount);

*utime = t->utime;
*stime = t->stime;

/* Task is sleeping, nothing to add */
if (t->vtime_state == VTIME_INACTIVE || is_idle_task(t))
if (vtime->state == VTIME_INACTIVE || is_idle_task(t))
continue;

delta = vtime_delta(t);
delta = vtime_delta(vtime);

/*
* Task runs either in user or kernel space, add pending nohz time to
* the right place.
*/
if (t->vtime_state == VTIME_USER || t->flags & PF_VCPU)
if (vtime->state == VTIME_USER || t->flags & PF_VCPU)
*utime += delta;
else if (t->vtime_state == VTIME_SYS)
else if (vtime->state == VTIME_SYS)
*stime += delta;
} while (read_seqcount_retry(&t->vtime_seqcount, seq));
} while (read_seqcount_retry(&vtime->seqcount, seq));
}
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */

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