[PATCH 0/4] cputime: Even more cleanups

[PATCH 0/4] cputime: Even more cleanups

[Frederic Weisbecker]

Hi,

While working on full dynticks, I realized some more cleanups needed to be
done. Here is it. If no comment arise, I'll send a pull request to Ingo
in a week.

Thanks.

Frederic Weisbecker (4):
  vtime: Remove the underscore prefix invasion
  vtime: Explicitly account pending user time on process tick
  vtime: Consolidate a bit the ctx switch code
  vtime: No need to disable irqs on vtime_account()

 arch/ia64/include/asm/cputime.h    |    2 ++
 arch/ia64/kernel/time.c            |   24 ++++--------------------
 arch/powerpc/include/asm/cputime.h |    2 ++
 arch/powerpc/kernel/time.c         |   22 ++++++++--------------
 arch/s390/include/asm/cputime.h    |    1 +
 arch/s390/kernel/vtime.c           |   11 ++++++++---
 include/linux/kernel_stat.h        |    8 ++++++++
 include/linux/kvm_host.h           |    4 ++--
 include/linux/vtime.h              |    9 +++++----
 kernel/sched/cputime.c             |   31 +++++++++++++++++++------------
 10 files changed, 59 insertions(+), 55 deletions(-)

-- 
1.7.5.4

[PATCH 1/4] vtime: Remove the underscore prefix invasion

[Frederic Weisbecker]

Prepending irq-unsafe vtime APIs with underscores was actually
a bad idea as the result is a big mess in the API namespace that
is even waiting to be further extended. Also these helpers
are always called from irq safe callers except kvm. Just
provide a vtime_account_system_irqsafe() for this specific
case so that we can remove the underscore prefix on other
vtime functions.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
 arch/ia64/kernel/time.c    |    8 ++++----
 arch/powerpc/kernel/time.c |    4 ++--
 arch/s390/kernel/vtime.c   |    4 ++--
 include/linux/kvm_host.h   |    4 ++--
 include/linux/vtime.h      |    8 ++++----
 kernel/sched/cputime.c     |   12 ++++++------
 6 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 5e48503..f638821 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -106,9 +106,9 @@ void vtime_task_switch(struct task_struct *prev)
 	struct thread_info *ni = task_thread_info(current);
 
 	if (idle_task(smp_processor_id()) != prev)
-		__vtime_account_system(prev);
+		vtime_account_system(prev);
 	else
-		__vtime_account_idle(prev);
+		vtime_account_idle(prev);
 
 	vtime_account_user(prev);
 
@@ -135,14 +135,14 @@ static cputime_t vtime_delta(struct task_struct *tsk)
 	return delta_stime;
 }
 
-void __vtime_account_system(struct task_struct *tsk)
+void vtime_account_system(struct task_struct *tsk)
 {
 	cputime_t delta = vtime_delta(tsk);
 
 	account_system_time(tsk, 0, delta, delta);
 }
 
-void __vtime_account_idle(struct task_struct *tsk)
+void vtime_account_idle(struct task_struct *tsk)
 {
 	account_idle_time(vtime_delta(tsk));
 }
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 0db456f..ce4cb77 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -336,7 +336,7 @@ static u64 vtime_delta(struct task_struct *tsk,
 	return delta;
 }
 
-void __vtime_account_system(struct task_struct *tsk)
+void vtime_account_system(struct task_struct *tsk)
 {
 	u64 delta, sys_scaled, stolen;
 
@@ -346,7 +346,7 @@ void __vtime_account_system(struct task_struct *tsk)
 		account_steal_time(stolen);
 }
 
-void __vtime_account_idle(struct task_struct *tsk)
+void vtime_account_idle(struct task_struct *tsk)
 {
 	u64 delta, sys_scaled, stolen;
 
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 783e988..80d1dbc 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -140,9 +140,9 @@ void vtime_account(struct task_struct *tsk)
 }
 EXPORT_SYMBOL_GPL(vtime_account);
 
-void __vtime_account_system(struct task_struct *tsk)
+void vtime_account_system(struct task_struct *tsk)
 __attribute__((alias("vtime_account")));
-EXPORT_SYMBOL_GPL(__vtime_account_system);
+EXPORT_SYMBOL_GPL(vtime_account_system);
 
 void __kprobes vtime_stop_cpu(void)
 {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0e2212f..f17158b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -741,7 +741,7 @@ static inline void kvm_guest_enter(void)
 	 * This is running in ioctl context so we can avoid
 	 * the call to vtime_account() with its unnecessary idle check.
 	 */
-	vtime_account_system(current);
+	vtime_account_system_irqsafe(current);
 	current->flags |= PF_VCPU;
 	/* KVM does not hold any references to rcu protected data when it
 	 * switches CPU into a guest mode. In fact switching to a guest mode
@@ -759,7 +759,7 @@ static inline void kvm_guest_exit(void)
 	 * This is running in ioctl context so we can avoid
 	 * the call to vtime_account() with its unnecessary idle check.
 	 */
-	vtime_account_system(current);
+	vtime_account_system_irqsafe(current);
 	current->flags &= ~PF_VCPU;
 }
 
diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index 0c2a2d3..5ad13c3 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -5,14 +5,14 @@ struct task_struct;
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 extern void vtime_task_switch(struct task_struct *prev);
-extern void __vtime_account_system(struct task_struct *tsk);
 extern void vtime_account_system(struct task_struct *tsk);
-extern void __vtime_account_idle(struct task_struct *tsk);
+extern void vtime_account_system_irqsafe(struct task_struct *tsk);
+extern void vtime_account_idle(struct task_struct *tsk);
 extern void vtime_account(struct task_struct *tsk);
 #else
 static inline void vtime_task_switch(struct task_struct *prev) { }
-static inline void __vtime_account_system(struct task_struct *tsk) { }
 static inline void vtime_account_system(struct task_struct *tsk) { }
+static inline void vtime_account_system_irqsafe(struct task_struct *tsk) { }
 static inline void vtime_account(struct task_struct *tsk) { }
 #endif
 
@@ -40,7 +40,7 @@ static inline void vtime_account_irq_enter(struct task_struct *tsk)
 static inline void vtime_account_irq_exit(struct task_struct *tsk)
 {
 	/* On hard|softirq exit we always account to hard|softirq cputime */
-	__vtime_account_system(tsk);
+	vtime_account_system(tsk);
 	irqtime_account_irq(tsk);
 }
 
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 8d859da..c0aa1ba 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -433,20 +433,20 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
 	*st = cputime.stime;
 }
 
-void vtime_account_system(struct task_struct *tsk)
+void vtime_account_system_irqsafe(struct task_struct *tsk)
 {
 	unsigned long flags;
 
 	local_irq_save(flags);
-	__vtime_account_system(tsk);
+	vtime_account_system(tsk);
 	local_irq_restore(flags);
 }
-EXPORT_SYMBOL_GPL(vtime_account_system);
+EXPORT_SYMBOL_GPL(vtime_account_system_irqsafe);
 
 /*
  * Archs that account the whole time spent in the idle task
  * (outside irq) as idle time can rely on this and just implement
- * __vtime_account_system() and __vtime_account_idle(). Archs that
+ * vtime_account_system() and vtime_account_idle(). Archs that
  * have other meaning of the idle time (s390 only includes the
  * time spent by the CPU when it's in low power mode) must override
  * vtime_account().
@@ -459,9 +459,9 @@ void vtime_account(struct task_struct *tsk)
 	local_irq_save(flags);
 
 	if (in_interrupt() || !is_idle_task(tsk))
-		__vtime_account_system(tsk);
+		vtime_account_system(tsk);
 	else
-		__vtime_account_idle(tsk);
+		vtime_account_idle(tsk);
 
 	local_irq_restore(flags);
 }
-- 
1.7.5.4

[PATCH 2/4] vtime: Explicitly account pending user time on process tick

[Frederic Weisbecker]

All vtime implementations just flush the user time on process
tick. Consolidate that in generic code by calling a user time
accounting helper. This avoids an indirect call in ia64 and
prepare to also consolidate vtime context switch code.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
 arch/ia64/kernel/time.c     |   11 +----------
 arch/powerpc/kernel/time.c  |   14 +++++++-------
 arch/s390/kernel/vtime.c    |    7 ++++++-
 include/linux/kernel_stat.h |    8 ++++++++
 include/linux/vtime.h       |    1 +
 5 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index f638821..834c78b 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -83,7 +83,7 @@ static struct clocksource *itc_clocksource;
 
 extern cputime_t cycle_to_cputime(u64 cyc);
 
-static void vtime_account_user(struct task_struct *tsk)
+void vtime_account_user(struct task_struct *tsk)
 {
 	cputime_t delta_utime;
 	struct thread_info *ti = task_thread_info(tsk);
@@ -147,15 +147,6 @@ void vtime_account_idle(struct task_struct *tsk)
 	account_idle_time(vtime_delta(tsk));
 }
 
-/*
- * Called from the timer interrupt handler to charge accumulated user time
- * to the current process.  Must be called with interrupts disabled.
- */
-void account_process_tick(struct task_struct *p, int user_tick)
-{
-	vtime_account_user(p);
-}
-
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 
 static irqreturn_t
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index ce4cb77..a667aaf 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -355,15 +355,15 @@ void vtime_account_idle(struct task_struct *tsk)
 }
 
 /*
- * Transfer the user and system times accumulated in the paca
- * by the exception entry and exit code to the generic process
- * user and system time records.
+ * Transfer the user time accumulated in the paca
+ * by the exception entry and exit code to the generic
+ * process user time records.
  * Must be called with interrupts disabled.
- * Assumes that vtime_account() has been called recently
- * (i.e. since the last entry from usermode) so that
+ * Assumes that vtime_account_system/idle() has been called
+ * recently (i.e. since the last entry from usermode) so that
  * get_paca()->user_time_scaled is up to date.
  */
-void account_process_tick(struct task_struct *tsk, int user_tick)
+void vtime_account_user(struct task_struct *tsk)
 {
 	cputime_t utime, utimescaled;
 
@@ -378,7 +378,7 @@ void account_process_tick(struct task_struct *tsk, int user_tick)
 void vtime_task_switch(struct task_struct *prev)
 {
 	vtime_account(prev);
-	account_process_tick(prev, 0);
+	vtime_account_user(prev);
 }
 
 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 80d1dbc..7c6d861 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -112,7 +112,12 @@ void vtime_task_switch(struct task_struct *prev)
 	S390_lowcore.system_timer = ti->system_timer;
 }
 
-void account_process_tick(struct task_struct *tsk, int user_tick)
+/*
+ * In s390, accounting pending user time also implies
+ * accounting system time in order to correctly compute
+ * the stolen time accounting.
+ */
+void vtime_account_user(struct task_struct *tsk)
 {
 	if (do_account_vtime(tsk, HARDIRQ_OFFSET))
 		virt_timer_expire();
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index 1865b1f..66b7078 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -127,7 +127,15 @@ extern void account_system_time(struct task_struct *, int, cputime_t, cputime_t)
 extern void account_steal_time(cputime_t);
 extern void account_idle_time(cputime_t);
 
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING
+static inline void account_process_tick(struct task_struct *tsk, int user)
+{
+	vtime_account_user(tsk);
+}
+#else
 extern void account_process_tick(struct task_struct *, int user);
+#endif
+
 extern void account_steal_ticks(unsigned long ticks);
 extern void account_idle_ticks(unsigned long ticks);
 
diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index 5ad13c3..ae30ab5 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -8,6 +8,7 @@ extern void vtime_task_switch(struct task_struct *prev);
 extern void vtime_account_system(struct task_struct *tsk);
 extern void vtime_account_system_irqsafe(struct task_struct *tsk);
 extern void vtime_account_idle(struct task_struct *tsk);
+extern void vtime_account_user(struct task_struct *tsk);
 extern void vtime_account(struct task_struct *tsk);
 #else
 static inline void vtime_task_switch(struct task_struct *prev) { }
-- 
1.7.5.4

[PATCH 3/4] vtime: Consolidate a bit the ctx switch code

[Frederic Weisbecker]

On ia64 and powerpc, vtime context switch only consists
in flushing system and user pending time, plus a few
arch housekeeping.

Consolidate that into a generic implementation. s390 is
a special case because pending user and system time accounting
there is hard to dissociate. So it's keeping its own implementation.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
 arch/ia64/include/asm/cputime.h    |    2 ++
 arch/ia64/kernel/time.c            |    9 +--------
 arch/powerpc/include/asm/cputime.h |    2 ++
 arch/powerpc/kernel/time.c         |    6 ------
 arch/s390/include/asm/cputime.h    |    1 +
 kernel/sched/cputime.c             |   13 +++++++++++++
 6 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/arch/ia64/include/asm/cputime.h b/arch/ia64/include/asm/cputime.h
index 3deac95..7fcf7f0 100644
--- a/arch/ia64/include/asm/cputime.h
+++ b/arch/ia64/include/asm/cputime.h
@@ -103,5 +103,7 @@ static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)
 #define cputime64_to_clock_t(__ct)	\
 	cputime_to_clock_t((__force cputime_t)__ct)
 
+extern void arch_vtime_task_switch(struct task_struct *tsk);
+
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 #endif /* __IA64_CPUTIME_H */
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 834c78b..c9a7d2e 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -100,18 +100,11 @@ void vtime_account_user(struct task_struct *tsk)
  * accumulated times to the current process, and to prepare accounting on
  * the next process.
  */
-void vtime_task_switch(struct task_struct *prev)
+void arch_vtime_task_switch(struct task_struct *prev)
 {
 	struct thread_info *pi = task_thread_info(prev);
 	struct thread_info *ni = task_thread_info(current);
 
-	if (idle_task(smp_processor_id()) != prev)
-		vtime_account_system(prev);
-	else
-		vtime_account_idle(prev);
-
-	vtime_account_user(prev);
-
 	pi->ac_stamp = ni->ac_stamp;
 	ni->ac_stime = ni->ac_utime = 0;
 }
diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h
index 487d46f..483733b 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -228,6 +228,8 @@ static inline cputime_t clock_t_to_cputime(const unsigned long clk)
 
 #define cputime64_to_clock_t(ct)	cputime_to_clock_t((cputime_t)(ct))
 
+static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
+
 #endif /* __KERNEL__ */
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 #endif /* __POWERPC_CPUTIME_H */
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index a667aaf..3486cfa 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -375,12 +375,6 @@ void vtime_account_user(struct task_struct *tsk)
 	account_user_time(tsk, utime, utimescaled);
 }
 
-void vtime_task_switch(struct task_struct *prev)
-{
-	vtime_account(prev);
-	vtime_account_user(prev);
-}
-
 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
 #define calc_cputime_factors()
 #endif
diff --git a/arch/s390/include/asm/cputime.h b/arch/s390/include/asm/cputime.h
index 023d5ae..d2ff4137 100644
--- a/arch/s390/include/asm/cputime.h
+++ b/arch/s390/include/asm/cputime.h
@@ -14,6 +14,7 @@
 
 
 #define __ARCH_HAS_VTIME_ACCOUNT
+#define __ARCH_HAS_VTIME_TASK_SWITCH
 
 /* We want to use full resolution of the CPU timer: 2**-12 micro-seconds. */
 
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index c0aa1ba..2e8d34a 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -443,6 +443,19 @@ void vtime_account_system_irqsafe(struct task_struct *tsk)
 }
 EXPORT_SYMBOL_GPL(vtime_account_system_irqsafe);
 
+#ifndef __ARCH_HAS_VTIME_TASK_SWITCH
+void vtime_task_switch(struct task_struct *prev)
+{
+	if (is_idle_task(prev))
+		vtime_account_idle(prev);
+	else
+		vtime_account_system(prev);
+
+	vtime_account_user(prev);
+	arch_vtime_task_switch(prev);
+}
+#endif
+
 /*
  * Archs that account the whole time spent in the idle task
  * (outside irq) as idle time can rely on this and just implement
-- 
1.7.5.4

[PATCH 4/4] vtime: No need to disable irqs on vtime_account()

[Frederic Weisbecker]

vtime_account() is only called from irq entry. irqs
are always disabled at this point so we can safely
remove the irq disabling guards on that function.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
 kernel/sched/cputime.c |    6 ------
 1 files changed, 0 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 2e8d34a..80b2fd5 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -467,16 +467,10 @@ void vtime_task_switch(struct task_struct *prev)
 #ifndef __ARCH_HAS_VTIME_ACCOUNT
 void vtime_account(struct task_struct *tsk)
 {
-	unsigned long flags;
-
-	local_irq_save(flags);
-
 	if (in_interrupt() || !is_idle_task(tsk))
 		vtime_account_system(tsk);
 	else
 		vtime_account_idle(tsk);
-
-	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(vtime_account);
 #endif /* __ARCH_HAS_VTIME_ACCOUNT */
-- 
1.7.5.4

Re: [PATCH 1/4] vtime: Remove the underscore prefix invasion

[Steven Rostedt]

On Wed, 2012-11-14 at 17:26 +0100, Frederic Weisbecker wrote:
> Prepending irq-unsafe vtime APIs with underscores was actually
> a bad idea as the result is a big mess in the API namespace that
> is even waiting to be further extended. Also these helpers
> are always called from irq safe callers except kvm. Just
> provide a vtime_account_system_irqsafe() for this specific
> case so that we can remove the underscore prefix on other
> vtime functions.
> 

 
> -void __vtime_account_system(struct task_struct *tsk)
> +void vtime_account_system(struct task_struct *tsk)
>  {
>  	cputime_t delta = vtime_delta(tsk);

Should we add a WARN_ON(!irqs_disabled()) check here?

-- Steve

>  
>  	account_system_time(tsk, 0, delta, delta);
>  }
>  
> -void __vtime_account_idle(struct task_struct *tsk)
> +void vtime_account_idle(struct task_struct *tsk)
>  {
>  	account_idle_time(vtime_delta(tsk));
>  }

Re: [PATCH 1/4] vtime: Remove the underscore prefix invasion

[Frederic Weisbecker]

2012/11/14 Steven Rostedt <rostedt@goodmis.org>:
> On Wed, 2012-11-14 at 17:26 +0100, Frederic Weisbecker wrote:
>> Prepending irq-unsafe vtime APIs with underscores was actually
>> a bad idea as the result is a big mess in the API namespace that
>> is even waiting to be further extended. Also these helpers
>> are always called from irq safe callers except kvm. Just
>> provide a vtime_account_system_irqsafe() for this specific
>> case so that we can remove the underscore prefix on other
>> vtime functions.
>>
>
>
>> -void __vtime_account_system(struct task_struct *tsk)
>> +void vtime_account_system(struct task_struct *tsk)
>>  {
>>       cputime_t delta = vtime_delta(tsk);
>
> Should we add a WARN_ON(!irqs_disabled()) check here?

Why not, I'll add one in vtime_delta().

Re: [PATCH 1/4] vtime: Remove the underscore prefix invasion

[Steven Rostedt]

On Wed, 2012-11-14 at 17:48 +0100, Frederic Weisbecker wrote:
> 2012/11/14 Steven Rostedt <rostedt@goodmis.org>:
> > On Wed, 2012-11-14 at 17:26 +0100, Frederic Weisbecker wrote:
> >> Prepending irq-unsafe vtime APIs with underscores was actually
> >> a bad idea as the result is a big mess in the API namespace that
> >> is even waiting to be further extended. Also these helpers
> >> are always called from irq safe callers except kvm. Just
> >> provide a vtime_account_system_irqsafe() for this specific
> >> case so that we can remove the underscore prefix on other
> >> vtime functions.
> >>
> >
> >
> >> -void __vtime_account_system(struct task_struct *tsk)
> >> +void vtime_account_system(struct task_struct *tsk)
> >>  {
> >>       cputime_t delta = vtime_delta(tsk);
> >
> > Should we add a WARN_ON(!irqs_disabled()) check here?
> 
> Why not, I'll add one in vtime_delta().

Probably make it a WARN_ON_ONCE() no need to spam the console.

-- Steve

Re: [PATCH 3/4] vtime: Consolidate a bit the ctx switch code

[Steven Rostedt]

from the subject: vtime: Consolidate a bit the ctx switch code

I read that line several times and it just keeps sounding like some
chant done by the strikers in Greece over the austerity measures...

  "Consolidate a bit! The context switch code!"
  "Consolidate a bit! The context switch code!"
  "Consolidate a bit! The context switch code!"
  "Consolidate a bit! The context switch code!"

I guess because it just sounds Greek to me.


-- Steve

Re: [PATCH 4/4] vtime: No need to disable irqs on vtime_account()

[Steven Rostedt]

On Wed, 2012-11-14 at 17:26 +0100, Frederic Weisbecker wrote:
> vtime_account() is only called from irq entry. irqs
> are always disabled at this point so we can safely
> remove the irq disabling guards on that function.
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> ---
>  kernel/sched/cputime.c |    6 ------
>  1 files changed, 0 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> index 2e8d34a..80b2fd5 100644
> --- a/kernel/sched/cputime.c
> +++ b/kernel/sched/cputime.c
> @@ -467,16 +467,10 @@ void vtime_task_switch(struct task_struct *prev)
>  #ifndef __ARCH_HAS_VTIME_ACCOUNT
>  void vtime_account(struct task_struct *tsk)
>  {
> -	unsigned long flags;
> -
> -	local_irq_save(flags);
> -

I'd add a WARN_ON_ONCE(!irqs_disabled()) again here, or is this also
covered by the vtime_delta()?

-- Steve

>  	if (in_interrupt() || !is_idle_task(tsk))
>  		vtime_account_system(tsk);
>  	else
>  		vtime_account_idle(tsk);
> -
> -	local_irq_restore(flags);
>  }
>  EXPORT_SYMBOL_GPL(vtime_account);
>  #endif /* __ARCH_HAS_VTIME_ACCOUNT */

Re: [PATCH 0/4] cputime: Even more cleanups

[Steven Rostedt]

On Wed, 2012-11-14 at 17:26 +0100, Frederic Weisbecker wrote:
> Hi,
> 
> While working on full dynticks, I realized some more cleanups needed to be
> done. Here is it. If no comment arise, I'll send a pull request to Ingo
> in a week.
> 

Other than what I've already commented on...

Reviewed-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve

> Thanks.
> 
> Frederic Weisbecker (4):
>   vtime: Remove the underscore prefix invasion
>   vtime: Explicitly account pending user time on process tick
>   vtime: Consolidate a bit the ctx switch code
>   vtime: No need to disable irqs on vtime_account()
> 
>  arch/ia64/include/asm/cputime.h    |    2 ++
>  arch/ia64/kernel/time.c            |   24 ++++--------------------
>  arch/powerpc/include/asm/cputime.h |    2 ++
>  arch/powerpc/kernel/time.c         |   22 ++++++++--------------
>  arch/s390/include/asm/cputime.h    |    1 +
>  arch/s390/kernel/vtime.c           |   11 ++++++++---
>  include/linux/kernel_stat.h        |    8 ++++++++
>  include/linux/kvm_host.h           |    4 ++--
>  include/linux/vtime.h              |    9 +++++----
>  kernel/sched/cputime.c             |   31 +++++++++++++++++++------------
>  10 files changed, 59 insertions(+), 55 deletions(-)
> 

Re: [PATCH 4/4] vtime: No need to disable irqs on vtime_account()

[Frederic Weisbecker]

2012/11/14 Steven Rostedt <rostedt@goodmis.org>:
> On Wed, 2012-11-14 at 17:26 +0100, Frederic Weisbecker wrote:
>> vtime_account() is only called from irq entry. irqs
>> are always disabled at this point so we can safely
>> remove the irq disabling guards on that function.
>>
>> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Cc: Ingo Molnar <mingo@kernel.org>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Steven Rostedt <rostedt@goodmis.org>
>> Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
>> Cc: Tony Luck <tony.luck@intel.com>
>> Cc: Fenghua Yu <fenghua.yu@intel.com>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
>> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
>> ---
>>  kernel/sched/cputime.c |    6 ------
>>  1 files changed, 0 insertions(+), 6 deletions(-)
>>
>> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
>> index 2e8d34a..80b2fd5 100644
>> --- a/kernel/sched/cputime.c
>> +++ b/kernel/sched/cputime.c
>> @@ -467,16 +467,10 @@ void vtime_task_switch(struct task_struct *prev)
>>  #ifndef __ARCH_HAS_VTIME_ACCOUNT
>>  void vtime_account(struct task_struct *tsk)
>>  {
>> -     unsigned long flags;
>> -
>> -     local_irq_save(flags);
>> -
>
> I'd add a WARN_ON_ONCE(!irqs_disabled()) again here, or is this also
> covered by the vtime_delta()?

Yeah it's the ending point for both vtime_account_system() and
vtime_account_idle()