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Commit 1f1c12af authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Linus Torvalds
Browse files

[PATCH] s390: cputime misaccounting 



finish_arch_switch needs to update the user cpu time as well, not just the
system cpu time.  Otherwise the partial user cpu time of a process that is
stored in the lowcore will be (mis-)accounted to the next process.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent bcc13265

arch/s390/kernel/time.c

+1 −1
Original line number Diff line number Diff line
@@ -214,7 +214,7 @@ void account_ticks(struct pt_regs *regs) 
#endif



#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	account_user_vtime(current);

	account_tick_vtime(current);

#else

	while (ticks--)

		update_process_times(user_mode(regs));

arch/s390/kernel/vtime.c

+26 −1
Original line number Diff line number Diff line
@@ -32,7 +32,7 @@ DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer); 
 * Update process times based on virtual cpu times stored by entry.S

 * to the lowcore fields user_timer, system_timer & steal_clock.

 */

void account_user_vtime(struct task_struct *tsk)

void account_tick_vtime(struct task_struct *tsk)

{

	cputime_t cputime;

	__u64 timer, clock;
@@ -72,6 +72,31 @@ void account_user_vtime(struct task_struct *tsk) 
 	run_posix_cpu_timers(tsk);

}



/*

 * Update process times based on virtual cpu times stored by entry.S

 * to the lowcore fields user_timer, system_timer & steal_clock.

 */

void account_vtime(struct task_struct *tsk)

{

	cputime_t cputime;

	__u64 timer;



	timer = S390_lowcore.last_update_timer;

	asm volatile ("  STPT %0"    /* Store current cpu timer value */

		      : "=m" (S390_lowcore.last_update_timer) );

	S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;



	cputime = S390_lowcore.user_timer >> 12;

	S390_lowcore.user_timer -= cputime << 12;

	S390_lowcore.steal_clock -= cputime << 12;

	account_user_time(tsk, cputime);



	cputime =  S390_lowcore.system_timer >> 12;

	S390_lowcore.system_timer -= cputime << 12;

	S390_lowcore.steal_clock -= cputime << 12;

	account_system_time(tsk, 0, cputime);

}



/*

 * Update process times based on virtual cpu times stored by entry.S

 * to the lowcore fields user_timer, system_timer & steal_clock.

include/asm-s390/system.h

+3 −2
Original line number Diff line number Diff line
@@ -115,13 +115,14 @@ static inline void sched_cacheflush(void) 
}



#ifdef CONFIG_VIRT_CPU_ACCOUNTING

extern void account_user_vtime(struct task_struct *);

extern void account_vtime(struct task_struct *);

extern void account_tick_vtime(struct task_struct *);

extern void account_system_vtime(struct task_struct *);

#endif



#define finish_arch_switch(prev) do {					     \

	set_fs(current->thread.mm_segment);				     \

	account_system_vtime(prev);					     \

	account_vtime(prev);						     \

} while (0)



#define nop() __asm__ __volatile__ ("nop")

include/linux/hardirq.h

+0 −4
Original line number Diff line number Diff line
@@ -93,10 +93,6 @@ extern void synchronize_irq(unsigned int irq); 
struct task_struct;



#ifndef CONFIG_VIRT_CPU_ACCOUNTING

static inline void account_user_vtime(struct task_struct *tsk)

{

}



static inline void account_system_vtime(struct task_struct *tsk)

{

}