Commit e6e6685a authored by Glauber Costa's avatar Glauber Costa Committed by Avi Kivity
Browse files

KVM guest: Steal time accounting 



This patch accounts steal time time in account_process_tick.
If one or more tick is considered stolen in the current
accounting cycle, user/system accounting is skipped. Idle is fine,
since the hypervisor does not report steal time if the guest
is halted.

Accounting steal time from the core scheduler give us the
advantage of direct acess to the runqueue data. In a later
opportunity, it can be used to tweak cpu power and make
the scheduler aware of the time it lost.

[avi: <asm/paravirt.h> doesn't exist on many archs]

Signed-off-by: default avatarGlauber Costa <glommer@redhat.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Tested-by: default avatarEric B Munson <emunson@mgebm.net>
CC: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
CC: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 747f2925

kernel/sched.c

+43 −0
Original line number Original line Diff line number Diff line
@@ -75,6 +75,9 @@ 
#include <asm/tlb.h>

#include <asm/tlb.h>

#include <asm/irq_regs.h>

#include <asm/irq_regs.h>

#include <asm/mutex.h>

#include <asm/mutex.h>

#ifdef CONFIG_PARAVIRT

#include <asm/paravirt.h>

#endif





#include "sched_cpupri.h"

#include "sched_cpupri.h"

#include "workqueue_sched.h"

#include "workqueue_sched.h"
@@ -528,6 +531,9 @@ struct rq { 
#ifdef CONFIG_IRQ_TIME_ACCOUNTING

#ifdef CONFIG_IRQ_TIME_ACCOUNTING

	u64 prev_irq_time;

	u64 prev_irq_time;

#endif

#endif

#ifdef CONFIG_PARAVIRT

	u64 prev_steal_time;

#endif





	/* calc_load related fields */

	/* calc_load related fields */

	unsigned long calc_load_update;

	unsigned long calc_load_update;
@@ -1953,6 +1959,18 @@ void account_system_vtime(struct task_struct *curr) 
}

}

EXPORT_SYMBOL_GPL(account_system_vtime);

EXPORT_SYMBOL_GPL(account_system_vtime);





#endif /* CONFIG_IRQ_TIME_ACCOUNTING */



#ifdef CONFIG_PARAVIRT

static inline u64 steal_ticks(u64 steal)

{

	if (unlikely(steal > NSEC_PER_SEC))

		return div_u64(steal, TICK_NSEC);



	return __iter_div_u64_rem(steal, TICK_NSEC, &steal);

}

#endif



static void update_rq_clock_task(struct rq *rq, s64 delta)

static void update_rq_clock_task(struct rq *rq, s64 delta)

{

{

	s64 irq_delta;

	s64 irq_delta;
@@ -3845,6 +3863,25 @@ void account_idle_time(cputime_t cputime) 
		cpustat->idle = cputime64_add(cpustat->idle, cputime64);

		cpustat->idle = cputime64_add(cpustat->idle, cputime64);

}

}





static __always_inline bool steal_account_process_tick(void)

{

#ifdef CONFIG_PARAVIRT

	if (static_branch(&paravirt_steal_enabled)) {

		u64 steal, st = 0;



		steal = paravirt_steal_clock(smp_processor_id());

		steal -= this_rq()->prev_steal_time;



		st = steal_ticks(steal);

		this_rq()->prev_steal_time += st * TICK_NSEC;



		account_steal_time(st);

		return st;

	}

#endif

	return false;

}



#ifndef CONFIG_VIRT_CPU_ACCOUNTING

#ifndef CONFIG_VIRT_CPU_ACCOUNTING





#ifdef CONFIG_IRQ_TIME_ACCOUNTING

#ifdef CONFIG_IRQ_TIME_ACCOUNTING
@@ -3876,6 +3913,9 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick, 
	cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);

	cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);

	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;

	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;





	if (steal_account_process_tick())

		return;



	if (irqtime_account_hi_update()) {

	if (irqtime_account_hi_update()) {

		cpustat->irq = cputime64_add(cpustat->irq, tmp);

		cpustat->irq = cputime64_add(cpustat->irq, tmp);

	} else if (irqtime_account_si_update()) {

	} else if (irqtime_account_si_update()) {
@@ -3929,6 +3969,9 @@ void account_process_tick(struct task_struct *p, int user_tick) 
		return;

		return;

	}

	}





	if (steal_account_process_tick())

		return;



	if (user_tick)

	if (user_tick)

		account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);

		account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);

	else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))

	else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))

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