From: Martin Schwidefsky 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: Martin Schwidefsky Signed-off-by: Andrew Morton --- arch/s390/kernel/time.c | 2 +- arch/s390/kernel/vtime.c | 27 ++++++++++++++++++++++++++- include/asm-s390/system.h | 5 +++-- include/linux/hardirq.h | 4 ---- 4 files changed, 30 insertions(+), 8 deletions(-) diff -puN arch/s390/kernel/time.c~s390-cputime-misaccounting arch/s390/kernel/time.c --- 25/arch/s390/kernel/time.c~s390-cputime-misaccounting Thu Jan 12 17:02:42 2006 +++ 25-akpm/arch/s390/kernel/time.c Thu Jan 12 17:02:42 2006 @@ -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)); diff -puN arch/s390/kernel/vtime.c~s390-cputime-misaccounting arch/s390/kernel/vtime.c --- 25/arch/s390/kernel/vtime.c~s390-cputime-misaccounting Thu Jan 12 17:02:42 2006 +++ 25-akpm/arch/s390/kernel/vtime.c Thu Jan 12 17:02:42 2006 @@ -32,7 +32,7 @@ DEFINE_PER_CPU(struct vtimer_queue, virt * 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; @@ -73,6 +73,31 @@ void account_user_vtime(struct task_stru } /* + * 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. */ diff -puN include/asm-s390/system.h~s390-cputime-misaccounting include/asm-s390/system.h --- 25/include/asm-s390/system.h~s390-cputime-misaccounting Thu Jan 12 17:02:42 2006 +++ 25-akpm/include/asm-s390/system.h Thu Jan 12 17:02:42 2006 @@ -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") diff -puN include/linux/hardirq.h~s390-cputime-misaccounting include/linux/hardirq.h --- 25/include/linux/hardirq.h~s390-cputime-misaccounting Thu Jan 12 17:02:42 2006 +++ 25-akpm/include/linux/hardirq.h Thu Jan 12 17:02:42 2006 @@ -93,10 +93,6 @@ extern void synchronize_irq(unsigned int 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) { } _