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


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