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Message-ID: <18220.26005.778223.84644@cargo.ozlabs.ibm.com>
Date: Sat, 3 Nov 2007 23:12:05 +1100
From: Paul Mackerras <paulus@...ba.org>
To: Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Thomas Gleixner <tglx@...utronix.de>
CC: Christian Borntraeger <borntraeger@...ibm.com>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org
Subject: [PATCH v2] Restore deterministic CPU accounting on powerpc
Since powerpc started using CONFIG_GENERIC_CLOCKEVENTS, the
deterministic CPU accounting (CONFIG_VIRT_CPU_ACCOUNTING) has been
broken on powerpc, because we end up counting user time twice: once in
timer_interrupt() and once in update_process_times().
This fixes the problem by pulling the code in update_process_times
that updates utime and stime into a separate function called
account_process_tick. If CONFIG_VIRT_CPU_ACCOUNTING is not defined,
there is a version of account_process_tick in kernel/timer.c that
simply accounts a whole tick to either utime or stime as before. If
CONFIG_VIRT_CPU_ACCOUNTING is defined, then arch code gets to
implement account_process_tick.
This also lets us simplify the s390 code a bit; it means that the s390
timer interrupt can now call update_process_times even when
CONFIG_VIRT_CPU_ACCOUNTING is turned on, and can just implement a
suitable account_process_tick().
Signed-off-by: Paul Mackerras <paulus@...ba.org>
---
account_process_tick now takes the task_struct * as an argument.
Tested both with and without CONFIG_VIRT_CPU_ACCOUNTING.
arch/powerpc/kernel/process.c | 2 +-
arch/powerpc/kernel/time.c | 25 +------------------------
arch/s390/kernel/time.c | 4 ----
arch/s390/kernel/vtime.c | 8 +-------
include/linux/sched.h | 1 +
kernel/timer.c | 21 ++++++++++++++-------
6 files changed, 18 insertions(+), 43 deletions(-)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index b9d8837..41e13f4 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -350,7 +350,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
local_irq_save(flags);
account_system_vtime(current);
- account_process_vtime(current);
+ account_process_tick(current, 0);
calculate_steal_time();
last = _switch(old_thread, new_thread);
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 9eb3284..a70dfb7 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -259,7 +259,7 @@ void account_system_vtime(struct task_struct *tsk)
* user and system time records.
* Must be called with interrupts disabled.
*/
-void account_process_vtime(struct task_struct *tsk)
+void account_process_tick(struct task_struct *tsk, int user_tick)
{
cputime_t utime, utimescaled;
@@ -274,18 +274,6 @@ void account_process_vtime(struct task_struct *tsk)
account_user_time_scaled(tsk, utimescaled);
}
-static void account_process_time(struct pt_regs *regs)
-{
- int cpu = smp_processor_id();
-
- account_process_vtime(current);
- run_local_timers();
- if (rcu_pending(cpu))
- rcu_check_callbacks(cpu, user_mode(regs));
- scheduler_tick();
- run_posix_cpu_timers(current);
-}
-
/*
* Stuff for accounting stolen time.
*/
@@ -375,7 +363,6 @@ static void snapshot_purr(void)
#else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
#define calc_cputime_factors()
-#define account_process_time(regs) update_process_times(user_mode(regs))
#define calculate_steal_time() do { } while (0)
#endif
@@ -599,16 +586,6 @@ void timer_interrupt(struct pt_regs * regs)
get_lppaca()->int_dword.fields.decr_int = 0;
#endif
- /*
- * We cannot disable the decrementer, so in the period
- * between this cpu's being marked offline in cpu_online_map
- * and calling stop-self, it is taking timer interrupts.
- * Avoid calling into the scheduler rebalancing code if this
- * is the case.
- */
- if (!cpu_is_offline(cpu))
- account_process_time(regs);
-
if (evt->event_handler)
evt->event_handler(evt);
else
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 48dae49..6c6be1f 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -145,12 +145,8 @@ void account_ticks(u64 time)
do_timer(ticks);
#endif
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING
- account_tick_vtime(current);
-#else
while (ticks--)
update_process_times(user_mode(get_irq_regs()));
-#endif
s390_do_profile();
}
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 84ff78d..c5f05b3 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -32,7 +32,7 @@ static DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer);
* Update process times based on virtual cpu times stored by entry.S
* to the lowcore fields user_timer, system_timer & steal_clock.
*/
-void account_tick_vtime(struct task_struct *tsk)
+void account_process_tick(struct task_struct *tsk, int user_tick)
{
cputime_t cputime;
__u64 timer, clock;
@@ -64,12 +64,6 @@ void account_tick_vtime(struct task_struct *tsk)
S390_lowcore.steal_clock -= cputime << 12;
account_steal_time(tsk, cputime);
}
-
- run_local_timers();
- if (rcu_pending(smp_processor_id()))
- rcu_check_callbacks(smp_processor_id(), rcu_user_flag);
- scheduler_tick();
- run_posix_cpu_timers(tsk);
}
/*
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 155d743..8001528 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -254,6 +254,7 @@ long io_schedule_timeout(long timeout);
extern void cpu_init (void);
extern void trap_init(void);
+extern void account_process_tick(struct task_struct *task, int user);
extern void update_process_times(int user);
extern void scheduler_tick(void);
diff --git a/kernel/timer.c b/kernel/timer.c
index fb4e67d..ada3183 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -817,6 +817,19 @@ unsigned long next_timer_interrupt(void)
#endif
+#ifndef CONFIG_VIRT_CPU_ACCOUNTING
+void account_process_tick(struct task_struct *p, int user_tick)
+{
+ if (user_tick) {
+ account_user_time(p, jiffies_to_cputime(1));
+ account_user_time_scaled(p, jiffies_to_cputime(1));
+ } else {
+ account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
+ account_system_time_scaled(p, jiffies_to_cputime(1));
+ }
+}
+#endif
+
/*
* Called from the timer interrupt handler to charge one tick to the current
* process. user_tick is 1 if the tick is user time, 0 for system.
@@ -827,13 +840,7 @@ void update_process_times(int user_tick)
int cpu = smp_processor_id();
/* Note: this timer irq context must be accounted for as well. */
- if (user_tick) {
- account_user_time(p, jiffies_to_cputime(1));
- account_user_time_scaled(p, jiffies_to_cputime(1));
- } else {
- account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
- account_system_time_scaled(p, jiffies_to_cputime(1));
- }
+ account_process_tick(p, user_tick);
run_local_timers();
if (rcu_pending(cpu))
rcu_check_callbacks(cpu, user_tick);
-
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