Re: [PATCH v2] kvm: remove dependence on delay-accounting

[Konstantin Khlebnikov]

Marcelo Tosatti wrote:
> On Sat, Jan 14, 2012 at 08:30:51PM +0400, Konstantin Khlebnikov wrote:
> > KVM selects delay-accounting only to get sched-info for steal-time accounting.
> > Meanwhile delay-accounting can be disabled by boot option. This is ridiculous.
> >
> > This patch adds internal boolean option CONFIG_TASK_SCHED_INFO to enable only
> > task->sched_info and its collecting inside scheduler.

<cut>

> >   static inline int sched_info_on(void)
> >   {
> > -#ifdef CONFIG_SCHEDSTATS
> > +#if IS_ENABLED(CONFIG_SCHEDSTATS) || IS_ENABLED(CONFIG_KVM)
> >   	return 1;
>
> CONFIG_TASK_SCHED_INFO?

It makes it equal to constant 1, because all its callers are
under #ifdef CONFIG_TASK_SCHED_INFO =)

its current code:

static inline int sched_info_on(void)
{
#ifdef CONFIG_SCHEDSTATS
	return 1;
#elif defined(CONFIG_TASK_DELAY_ACCT)
	extern int delayacct_on;
	return delayacct_on;
#else
	return 0;
#endif
}

CONFIG_SCHEDSTATS == debug option in lib/Kconfig.debug for /proc/schedstat
CONFIG_TASK_DELAY_ACCT == wierd net-link based statistics collecting tool

Thus, may be better to remove this function, because it can return 0
only if delay-accounting is compiled but disabled by boot option
(delayacct_on =1 by default since 2.6.18)

patch follows...

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