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abf917cd91
If we want to stop the tick further idle, we need to be able to account the cputime without using the tick. Virtual based cputime accounting solves that problem by hooking into kernel/user boundaries. However implementing CONFIG_VIRT_CPU_ACCOUNTING require low level hooks and involves more overhead. But we already have a generic context tracking subsystem that is required for RCU needs by archs which plan to shut down the tick outside idle. This patch implements a generic virtual based cputime accounting that relies on these generic kernel/user hooks. There are some upsides of doing this: - This requires no arch code to implement CONFIG_VIRT_CPU_ACCOUNTING if context tracking is already built (already necessary for RCU in full tickless mode). - We can rely on the generic context tracking subsystem to dynamically (de)activate the hooks, so that we can switch anytime between virtual and tick based accounting. This way we don't have the overhead of the virtual accounting when the tick is running periodically. And one downside: - There is probably more overhead than a native virtual based cputime accounting. But this relies on hooks that are already set anyway. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
143 lines
3.3 KiB
C
143 lines
3.3 KiB
C
#ifndef _LINUX_KERNEL_STAT_H
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#define _LINUX_KERNEL_STAT_H
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#include <linux/smp.h>
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#include <linux/threads.h>
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#include <linux/percpu.h>
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#include <linux/cpumask.h>
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#include <linux/interrupt.h>
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#include <linux/sched.h>
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#include <linux/vtime.h>
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#include <asm/irq.h>
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#include <asm/cputime.h>
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/*
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* 'kernel_stat.h' contains the definitions needed for doing
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* some kernel statistics (CPU usage, context switches ...),
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* used by rstatd/perfmeter
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*/
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enum cpu_usage_stat {
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CPUTIME_USER,
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CPUTIME_NICE,
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CPUTIME_SYSTEM,
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CPUTIME_SOFTIRQ,
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CPUTIME_IRQ,
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CPUTIME_IDLE,
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CPUTIME_IOWAIT,
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CPUTIME_STEAL,
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CPUTIME_GUEST,
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CPUTIME_GUEST_NICE,
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NR_STATS,
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};
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struct kernel_cpustat {
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u64 cpustat[NR_STATS];
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};
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struct kernel_stat {
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#ifndef CONFIG_GENERIC_HARDIRQS
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unsigned int irqs[NR_IRQS];
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#endif
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unsigned long irqs_sum;
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unsigned int softirqs[NR_SOFTIRQS];
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};
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DECLARE_PER_CPU(struct kernel_stat, kstat);
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DECLARE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
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/* Must have preemption disabled for this to be meaningful. */
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#define kstat_this_cpu (&__get_cpu_var(kstat))
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#define kcpustat_this_cpu (&__get_cpu_var(kernel_cpustat))
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#define kstat_cpu(cpu) per_cpu(kstat, cpu)
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#define kcpustat_cpu(cpu) per_cpu(kernel_cpustat, cpu)
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extern unsigned long long nr_context_switches(void);
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#ifndef CONFIG_GENERIC_HARDIRQS
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struct irq_desc;
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static inline void kstat_incr_irqs_this_cpu(unsigned int irq,
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struct irq_desc *desc)
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{
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__this_cpu_inc(kstat.irqs[irq]);
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__this_cpu_inc(kstat.irqs_sum);
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}
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static inline unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
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{
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return kstat_cpu(cpu).irqs[irq];
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}
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#else
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#include <linux/irq.h>
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extern unsigned int kstat_irqs_cpu(unsigned int irq, int cpu);
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#define kstat_incr_irqs_this_cpu(irqno, DESC) \
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do { \
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__this_cpu_inc(*(DESC)->kstat_irqs); \
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__this_cpu_inc(kstat.irqs_sum); \
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} while (0)
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#endif
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static inline void kstat_incr_softirqs_this_cpu(unsigned int irq)
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{
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__this_cpu_inc(kstat.softirqs[irq]);
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}
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static inline unsigned int kstat_softirqs_cpu(unsigned int irq, int cpu)
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{
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return kstat_cpu(cpu).softirqs[irq];
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}
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/*
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* Number of interrupts per specific IRQ source, since bootup
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*/
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#ifndef CONFIG_GENERIC_HARDIRQS
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static inline unsigned int kstat_irqs(unsigned int irq)
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{
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unsigned int sum = 0;
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int cpu;
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for_each_possible_cpu(cpu)
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sum += kstat_irqs_cpu(irq, cpu);
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return sum;
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}
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#else
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extern unsigned int kstat_irqs(unsigned int irq);
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#endif
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/*
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* Number of interrupts per cpu, since bootup
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*/
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static inline unsigned int kstat_cpu_irqs_sum(unsigned int cpu)
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{
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return kstat_cpu(cpu).irqs_sum;
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}
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/*
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* Lock/unlock the current runqueue - to extract task statistics:
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*/
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extern unsigned long long task_delta_exec(struct task_struct *);
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extern void account_user_time(struct task_struct *, cputime_t, cputime_t);
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extern void account_system_time(struct task_struct *, int, cputime_t, cputime_t);
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extern void account_steal_time(cputime_t);
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extern void account_idle_time(cputime_t);
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#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
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static inline void account_process_tick(struct task_struct *tsk, int user)
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{
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vtime_account_user(tsk);
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}
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#else
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extern void account_process_tick(struct task_struct *, int user);
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#endif
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extern void account_steal_ticks(unsigned long ticks);
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extern void account_idle_ticks(unsigned long ticks);
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#endif /* _LINUX_KERNEL_STAT_H */
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