On Tue, 2013-01-08 at 03:08 +0100, Frederic Weisbecker wrote:
> +++ b/kernel/sched/cputime.c
> @@ -3,6 +3,7 @@
> #include <linux/tsacct_kern.h>
> #include <linux/kernel_stat.h>
> #include <linux/static_key.h>
> +#include <linux/context_tracking.h>
> #include "sched.h"
>
>
> @@ -495,10 +496,24 @@ void vtime_task_switch(struct task_struct *prev)
> #ifndef __ARCH_HAS_VTIME_ACCOUNT
> void vtime_account(struct task_struct *tsk)
> {
> - if (in_interrupt() || !is_idle_task(tsk))
> - vtime_account_system(tsk);
> - else
> - vtime_account_idle(tsk);
> + if (!in_interrupt()) {
> + /*
> + * If we interrupted user, context_tracking_in_user()
> + * is 1 because the context tracking don't hook
s/don't/doesn't/
> + * on irq entry/exit. This way we know if
> + * we need to flush user time on kernel entry.
Also, the above comment is simply confusing. Why not just say something
like:
Context tracking doesn't hook on irq entry/exit. The context will still
be user context if the interrupt preempted user space.
No need to explain the implementation details of
"context_tracing_in_user() is 1 ...".
-- Steve
> + */
> + if (context_tracking_in_user()) {
> + vtime_account_user(tsk);
> + return;
> + }
> +
> + if (is_idle_task(tsk)) {
> + vtime_account_idle(tsk);
> + return;
> + }
> + }
> + vtime_account_system(tsk);
> }
> EXPORT_SYMBOL_GPL(vtime_account);
> #endif /* __ARCH_HAS_VTIME_ACCOUNT */
> @@ -587,3 +602,72 @@ void thread_group_cputime_adjusted(struct task_struct
> *p, cputime_t *ut, cputime
> cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
> }
> #endif
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