sched/cputime: Convert task/group cputime to nsecs

Now that most cputime readers use the transition API which return the
task cputime in old style cputime_t, we can safely store the cputime in
nsecs. This will eventually make cputime statistics less opaque and more
granular. Back and forth convertions between cputime_t and nsecs in order
to deal with cputime_t random granularity won't be needed anymore.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-8-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/exit.c

@@ -86,7 +86,7 @@ static void __exit_signal(struct task_struct *tsk)
 	bool group_dead = thread_group_leader(tsk);
 	struct sighand_struct *sighand;
 	struct tty_struct *uninitialized_var(tty);
-	cputime_t utime, stime;
+	u64 utime, stime;
 
 	sighand = rcu_dereference_check(tsk->sighand,
 					lockdep_tasklist_lock_is_held());
@@ -1091,7 +1091,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 		struct signal_struct *sig = p->signal;
 		struct signal_struct *psig = current->signal;
 		unsigned long maxrss;
-		cputime_t tgutime, tgstime;
+		u64 tgutime, tgstime;
 
 		/*
 		 * The resource counters for the group leader are in its

kernel/sched/cputime.c

@@ -134,7 +134,7 @@ void account_user_time(struct task_struct *p, cputime_t cputime)
 	int index;
 
 	/* Add user time to process. */
-	p->utime += cputime;
+	p->utime += cputime_to_nsecs(cputime);
 	account_group_user_time(p, cputime);
 
 	index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
@@ -156,7 +156,7 @@ void account_guest_time(struct task_struct *p, cputime_t cputime)
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
 
 	/* Add guest time to process. */
-	p->utime += cputime;
+	p->utime += cputime_to_nsecs(cputime);
 	account_group_user_time(p, cputime);
 	p->gtime += cputime_to_nsecs(cputime);
 
@@ -180,7 +180,7 @@ void account_system_index_time(struct task_struct *p,
 			       cputime_t cputime, enum cpu_usage_stat index)
 {
 	/* Add system time to process. */
-	p->stime += cputime;
+	p->stime += cputime_to_nsecs(cputime);
 	account_group_system_time(p, cputime);
 
 	/* Add system time to cpustat. */
@@ -315,7 +315,7 @@ static u64 read_sum_exec_runtime(struct task_struct *t)
 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
 {
 	struct signal_struct *sig = tsk->signal;
-	cputime_t utime, stime;
+	u64 utime, stime;
 	struct task_struct *t;
 	unsigned int seq, nextseq;
 	unsigned long flags;
@@ -465,14 +465,14 @@ void vtime_account_irq_enter(struct task_struct *tsk)
 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
 #endif /* __ARCH_HAS_VTIME_ACCOUNT */
 
-void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
 {
 	*ut = p->utime;
 	*st = p->stime;
 }
 EXPORT_SYMBOL_GPL(task_cputime_adjusted);
 
-void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
 {
 	struct task_cputime cputime;
 
@@ -543,7 +543,7 @@ void account_idle_ticks(unsigned long ticks)
  * Perform (stime * rtime) / total, but avoid multiplication overflow by
  * loosing precision when the numbers are big.
  */
-static cputime_t scale_stime(u64 stime, u64 rtime, u64 total)
+static u64 scale_stime(u64 stime, u64 rtime, u64 total)
 {
 	u64 scaled;
 
@@ -580,7 +580,7 @@ drop_precision:
 	 * followed by a 64/32->64 divide.
 	 */
 	scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total);
-	return (__force cputime_t) scaled;
+	return scaled;
 }
 
 /*
@@ -605,14 +605,14 @@ drop_precision:
  */
 static void cputime_adjust(struct task_cputime *curr,
 			   struct prev_cputime *prev,
-			   cputime_t *ut, cputime_t *st)
+			   u64 *ut, u64 *st)
 {
-	cputime_t rtime, stime, utime;
+	u64 rtime, stime, utime;
 	unsigned long flags;
 
 	/* Serialize concurrent callers such that we can honour our guarantees */
 	raw_spin_lock_irqsave(&prev->lock, flags);
-	rtime = nsecs_to_cputime(curr->sum_exec_runtime);
+	rtime = curr->sum_exec_runtime;
 
 	/*
 	 * This is possible under two circumstances:
@@ -643,8 +643,7 @@ static void cputime_adjust(struct task_cputime *curr,
 		goto update;
 	}
 
-	stime = scale_stime((__force u64)stime, (__force u64)rtime,
-			    (__force u64)(stime + utime));
+	stime = scale_stime(stime, rtime, stime + utime);
 
 update:
 	/*
@@ -677,7 +676,7 @@ out:
 	raw_spin_unlock_irqrestore(&prev->lock, flags);
 }
 
-void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
 {
 	struct task_cputime cputime = {
 		.sum_exec_runtime = p->se.sum_exec_runtime,
@@ -688,7 +687,7 @@ void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 }
 EXPORT_SYMBOL_GPL(task_cputime_adjusted);
 
-void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
 {
 	struct task_cputime cputime;
 
@@ -849,9 +848,9 @@ u64 task_gtime(struct task_struct *t)
  * add up the pending nohz execution time since the last
  * cputime snapshot.
  */
-void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
+void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
 {
-	cputime_t delta;
+	u64 delta;
 	unsigned int seq;
 
 	if (!vtime_accounting_enabled()) {
@@ -870,7 +869,7 @@ void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
 		if (t->vtime_snap_whence == VTIME_INACTIVE || is_idle_task(t))
 			continue;
 
-		delta = vtime_delta(t);
+		delta = cputime_to_nsecs(vtime_delta(t));
 
 		/*
 		 * Task runs either in user or kernel space, add pending nohz time to

kernel/signal.c

@@ -1620,8 +1620,8 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
 	rcu_read_unlock();
 
 	task_cputime_t(tsk, &utime, &stime);
-	info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
-	info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
+	info.si_utime = cputime_to_clock_t(utime + nsecs_to_cputime(tsk->signal->utime));
+	info.si_stime = cputime_to_clock_t(stime + nsecs_to_cputime(tsk->signal->stime));
 
 	info.si_status = tsk->exit_code & 0x7f;
 	if (tsk->exit_code & 0x80)

kernel/sys.c

@@ -881,15 +881,15 @@ SYSCALL_DEFINE0(getegid)
 
 void do_sys_times(struct tms *tms)
 {
-	cputime_t tgutime, tgstime, cutime, cstime;
+	u64 tgutime, tgstime, cutime, cstime;
 
 	thread_group_cputime_adjusted(current, &tgutime, &tgstime);
 	cutime = current->signal->cutime;
 	cstime = current->signal->cstime;
-	tms->tms_utime = cputime_to_clock_t(tgutime);
-	tms->tms_stime = cputime_to_clock_t(tgstime);
-	tms->tms_cutime = cputime_to_clock_t(cutime);
-	tms->tms_cstime = cputime_to_clock_t(cstime);
+	tms->tms_utime = nsec_to_clock_t(tgutime);
+	tms->tms_stime = nsec_to_clock_t(tgstime);
+	tms->tms_cutime = nsec_to_clock_t(cutime);
+	tms->tms_cstime = nsec_to_clock_t(cstime);
 }
 
 SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
@@ -1544,7 +1544,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
 {
 	struct task_struct *t;
 	unsigned long flags;
-	cputime_t tgutime, tgstime, utime, stime;
+	u64 tgutime, tgstime, utime, stime;
 	unsigned long maxrss = 0;
 
 	memset((char *)r, 0, sizeof (*r));
@@ -1600,8 +1600,8 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
 	unlock_task_sighand(p, &flags);
 
 out:
-	cputime_to_timeval(utime, &r->ru_utime);
-	cputime_to_timeval(stime, &r->ru_stime);
+	r->ru_utime = ns_to_timeval(utime);
+	r->ru_stime = ns_to_timeval(stime);
 
 	if (who != RUSAGE_CHILDREN) {
 		struct mm_struct *mm = get_task_mm(p);