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cputime: Safely read cputime of full dynticks CPUs

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While remotely reading the cputime of a task running in a
full dynticks CPU, the values stored in utime/stime fields
of struct task_struct may be stale. Its values may be those
of the last kernel <-> user transition time snapshot and
we need to add the tickless time spent since this snapshot.

To fix this, flush the cputime of the dynticks CPUs on
kernel <-> user transition and record the time / context
where we did this. Then on top of this snapshot and the current
time, perform the fixup on the reader side from task_times()
accessors.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
[fixed kvm module related build errors]
Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
This commit is contained in:
Frederic Weisbecker 2012-12-16 20:00:34 +01:00
parent c11f11fcbd
commit 6a61671bb2
11 changed files with 292 additions and 54 deletions
Download patch file Download diff file Expand all files Collapse all files

20
include/linux/kvm_host.h
View file

@ -741,7 +741,7 @@ static inline int kvm_deassign_device(struct kvm *kvm,
}
#endif /* CONFIG_IOMMU_API */
static inline void guest_enter(void)
static inline void __guest_enter(void)
{
/*
* This is running in ioctl context so we can avoid
@ -751,7 +751,7 @@ static inline void guest_enter(void)
current->flags |= PF_VCPU;
}
static inline void guest_exit(void)
static inline void __guest_exit(void)
{
/*
* This is running in ioctl context so we can avoid
@ -761,6 +761,22 @@ static inline void guest_exit(void)
current->flags &= ~PF_VCPU;
}
#ifdef CONFIG_CONTEXT_TRACKING
extern void guest_enter(void);
extern void guest_exit(void);
#else /* !CONFIG_CONTEXT_TRACKING */
static inline void guest_enter(void)
{
__guest_enter();
}
static inline void guest_exit(void)
{
__guest_exit();
}
#endif /* !CONFIG_CONTEXT_TRACKING */
static inline void kvm_guest_enter(void)
{
unsigned long flags;