linux-kernel - Re: [PATCH 02/24] cputime: Generic on-demand virtual cputime accounting

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Message-ID: <1356066698.5896.90.camel@gandalf.local.home>
Date:	Fri, 21 Dec 2012 00:11:38 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Alessio Igor Bogani <abogani@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Avi Kivity <avi@...hat.com>,
	Chris Metcalf <cmetcalf@...era.com>,
	Christoph Lameter <cl@...ux.com>,
	Geoff Levand <geoff@...radead.org>,
	Gilad Ben Yossef <gilad@...yossef.com>,
	Hakan Akkan <hakanakkan@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 02/24] cputime: Generic on-demand virtual cputime
 accounting

On Thu, 2012-12-20 at 19:32 +0100, Frederic Weisbecker wrote:

> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> index 293b202..da0a9e7 100644
> --- a/kernel/sched/cputime.c
> +++ 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
> +		 * on irq entry/exit. This way we know if
> +		 * we need to flush user time on kernel entry.
> +		 */
> +		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 */
> @@ -586,4 +601,72 @@ void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime
>  	thread_group_cputime(p, &cputime);
>  	cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
>  }
> -#endif

Deleted #endif here.

> +
> +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN

Added #ifdef here.

> +static DEFINE_PER_CPU(long, last_jiffies) = INITIAL_JIFFIES;
> +
> +static cputime_t get_vtime_delta(void)
> +{
> +	long delta;
> +
> +	delta = jiffies - __this_cpu_read(last_jiffies);
> +	__this_cpu_add(last_jiffies, delta);
> +
> +	return jiffies_to_cputime(delta);
> +}
> +
> +void vtime_account_system(struct task_struct *tsk)
> +{
> +	cputime_t delta_cpu = get_vtime_delta();
> +
> +	account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
> +}
> +
> +void vtime_account_user(struct task_struct *tsk)
> +{
> +	cputime_t delta_cpu = get_vtime_delta();
> +
> +	/*
> +	 * This is an unfortunate hack: if we flush user time only on
> +	 * irq entry, we miss the jiffies update and the time is spuriously
> +	 * accounted to system time.
> +	 */
> +	if (context_tracking_in_user())
> +		account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
> +}
> +
> +void vtime_account_idle(struct task_struct *tsk)
> +{
> +	cputime_t delta_cpu = get_vtime_delta();
> +
> +	account_idle_time(delta_cpu);
> +}
> +
> +static int __cpuinit vtime_cpu_notify(struct notifier_block *self,
> +				      unsigned long action, void *hcpu)
> +{
> +	long cpu = (long)hcpu;
> +	long *last_jiffies_cpu = per_cpu_ptr(&last_jiffies, cpu);
> +
> +	switch (action) {
> +	case CPU_UP_PREPARE:
> +	case CPU_UP_PREPARE_FROZEN:
> +		/*
> +		 * CHECKME: ensure that's visible by the CPU
> +		 * once it wakes up
> +		 */
> +		*last_jiffies_cpu = jiffies;
> +	default:
> +		break;
> +	}
> +
> +	return NOTIFY_OK;
> +}
> +
> +static int __init init_vtime(void)
> +{
> +	cpu_notifier(vtime_cpu_notify, 0);
> +	return 0;
> +}
> +early_initcall(init_vtime);
> +#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */

Added #endif here

Hmm, missing #endif somewhere. Must explain my error message:

  kernel/sched/cputime.c:448:0: error: unterminated #else

Looks like a possible mismerge.

-- Steve



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