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sched: restore deterministic CPU accounting on powerpc

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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().

account_process_tick() now takes the task_struct * as an argument.
Tested both with and without CONFIG_VIRT_CPU_ACCOUNTING.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul Mackerras 2007-11-09 22:39:38 +01:00 committed by Ingo Molnar
parent 9a41785cc4
commit fa13a5a1f2
6 changed files with 18 additions and 43 deletions
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2
arch/powerpc/kernel/process.c
View file

@ -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);

25
arch/powerpc/kernel/time.c
View file

@ -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

4
arch/s390/kernel/time.c
View file

@ -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();
}

8
arch/s390/kernel/vtime.c
View file

@ -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);
}
/*

1
include/linux/sched.h
View file

@ -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);

21
kernel/timer.c
View file

@ -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);