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Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, tsc, sched: Recompute cyc2ns_offset's during resume from sleep states
  sched: Fix rq->clock synchronization when migrating tasks
This commit is contained in:
Linus Torvalds 2010-08-25 08:40:56 -07:00
commit 5e686019df
4 changed files with 44 additions and 0 deletions
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2
arch/x86/include/asm/tsc.h
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@ -59,5 +59,7 @@ extern void check_tsc_sync_source(int cpu);
extern void check_tsc_sync_target(void);
extern int notsc_setup(char *);
extern void save_sched_clock_state(void);
extern void restore_sched_clock_state(void);
#endif /* _ASM_X86_TSC_H */

38
arch/x86/kernel/tsc.c
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@ -626,6 +626,44 @@ static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
local_irq_restore(flags);
}
static unsigned long long cyc2ns_suspend;
void save_sched_clock_state(void)
{
if (!sched_clock_stable)
return;
cyc2ns_suspend = sched_clock();
}
/*
* Even on processors with invariant TSC, TSC gets reset in some the
* ACPI system sleep states. And in some systems BIOS seem to reinit TSC to
* arbitrary value (still sync'd across cpu's) during resume from such sleep
* states. To cope up with this, recompute the cyc2ns_offset for each cpu so
* that sched_clock() continues from the point where it was left off during
* suspend.
*/
void restore_sched_clock_state(void)
{
unsigned long long offset;
unsigned long flags;
int cpu;
if (!sched_clock_stable)
return;
local_irq_save(flags);
get_cpu_var(cyc2ns_offset) = 0;
offset = cyc2ns_suspend - sched_clock();
for_each_possible_cpu(cpu)
per_cpu(cyc2ns_offset, cpu) = offset;
local_irq_restore(flags);
}
#ifdef CONFIG_CPU_FREQ
/* Frequency scaling support. Adjust the TSC based timer when the cpu frequency

2
arch/x86/power/cpu.c
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@ -113,6 +113,7 @@ static void __save_processor_state(struct saved_context *ctxt)
void save_processor_state(void)
{
__save_processor_state(&saved_context);
save_sched_clock_state();
}
#ifdef CONFIG_X86_32
EXPORT_SYMBOL(save_processor_state);
@ -229,6 +230,7 @@ static void __restore_processor_state(struct saved_context *ctxt)
void restore_processor_state(void)
{
__restore_processor_state(&saved_context);
restore_sched_clock_state();
}
#ifdef CONFIG_X86_32
EXPORT_SYMBOL(restore_processor_state);

2
kernel/sched_fair.c
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@ -3752,6 +3752,8 @@ static void task_fork_fair(struct task_struct *p)
raw_spin_lock_irqsave(&rq->lock, flags);
update_rq_clock(rq);
if (unlikely(task_cpu(p) != this_cpu))
__set_task_cpu(p, this_cpu);