alistair23-linux/include/linux/kernel_stat.h
KAMEZAWA Hiroyuki 478735e388 /proc/stat: fix scalability of irq sum of all cpu
In /proc/stat, the number of per-IRQ event is shown by making a sum each
irq's events on all cpus.  But we can make use of kstat_irqs().

kstat_irqs() do the same calculation, If !CONFIG_GENERIC_HARDIRQ,
it's not a big cost. (Both of the number of cpus and irqs are small.)

If a system is very big and CONFIG_GENERIC_HARDIRQ, it does

	for_each_irq()
		for_each_cpu()
			- look up a radix tree
			- read desc->irq_stat[cpu]
This seems not efficient. This patch adds kstat_irqs() for
CONFIG_GENRIC_HARDIRQ and change the calculation as

	for_each_irq()
		look up radix tree
		for_each_cpu()
			- read desc->irq_stat[cpu]

This reduces cost.

A test on (4096cpusp, 256 nodes, 4592 irqs) host (by Jack Steiner)

%time cat /proc/stat > /dev/null

Before Patch:	 2.459 sec
After Patch :	  .561 sec

[akpm@linux-foundation.org: unexport kstat_irqs, coding-style tweaks]
[akpm@linux-foundation.org: fix unused variable 'per_irq_sum']
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tested-by: Jack Steiner <steiner@sgi.com>
Acked-by: Jack Steiner <steiner@sgi.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-27 18:03:13 -07:00

127 lines
3 KiB
C

#ifndef _LINUX_KERNEL_STAT_H
#define _LINUX_KERNEL_STAT_H
#include <linux/smp.h>
#include <linux/threads.h>
#include <linux/percpu.h>
#include <linux/cpumask.h>
#include <linux/interrupt.h>
#include <asm/irq.h>
#include <asm/cputime.h>
/*
* 'kernel_stat.h' contains the definitions needed for doing
* some kernel statistics (CPU usage, context switches ...),
* used by rstatd/perfmeter
*/
struct cpu_usage_stat {
cputime64_t user;
cputime64_t nice;
cputime64_t system;
cputime64_t softirq;
cputime64_t irq;
cputime64_t idle;
cputime64_t iowait;
cputime64_t steal;
cputime64_t guest;
cputime64_t guest_nice;
};
struct kernel_stat {
struct cpu_usage_stat cpustat;
#ifndef CONFIG_GENERIC_HARDIRQS
unsigned int irqs[NR_IRQS];
#endif
unsigned long irqs_sum;
unsigned int softirqs[NR_SOFTIRQS];
};
DECLARE_PER_CPU(struct kernel_stat, kstat);
#define kstat_cpu(cpu) per_cpu(kstat, cpu)
/* Must have preemption disabled for this to be meaningful. */
#define kstat_this_cpu __get_cpu_var(kstat)
extern unsigned long long nr_context_switches(void);
#ifndef CONFIG_GENERIC_HARDIRQS
#define kstat_irqs_this_cpu(irq) \
(kstat_this_cpu.irqs[irq])
struct irq_desc;
static inline void kstat_incr_irqs_this_cpu(unsigned int irq,
struct irq_desc *desc)
{
kstat_this_cpu.irqs[irq]++;
kstat_this_cpu.irqs_sum++;
}
static inline unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
{
return kstat_cpu(cpu).irqs[irq];
}
#else
#include <linux/irq.h>
extern unsigned int kstat_irqs_cpu(unsigned int irq, int cpu);
#define kstat_irqs_this_cpu(DESC) \
((DESC)->kstat_irqs[smp_processor_id()])
#define kstat_incr_irqs_this_cpu(irqno, DESC) do {\
((DESC)->kstat_irqs[smp_processor_id()]++);\
kstat_this_cpu.irqs_sum++; } while (0)
#endif
static inline void kstat_incr_softirqs_this_cpu(unsigned int irq)
{
kstat_this_cpu.softirqs[irq]++;
}
static inline unsigned int kstat_softirqs_cpu(unsigned int irq, int cpu)
{
return kstat_cpu(cpu).softirqs[irq];
}
/*
* Number of interrupts per specific IRQ source, since bootup
*/
#ifndef CONFIG_GENERIC_HARDIRQS
static inline unsigned int kstat_irqs(unsigned int irq)
{
unsigned int sum = 0;
int cpu;
for_each_possible_cpu(cpu)
sum += kstat_irqs_cpu(irq, cpu);
return sum;
}
#else
extern unsigned int kstat_irqs(unsigned int irq);
#endif
/*
* Number of interrupts per cpu, since bootup
*/
static inline unsigned int kstat_cpu_irqs_sum(unsigned int cpu)
{
return kstat_cpu(cpu).irqs_sum;
}
/*
* Lock/unlock the current runqueue - to extract task statistics:
*/
extern unsigned long long task_delta_exec(struct task_struct *);
extern void account_user_time(struct task_struct *, cputime_t, cputime_t);
extern void account_system_time(struct task_struct *, int, cputime_t, cputime_t);
extern void account_steal_time(cputime_t);
extern void account_idle_time(cputime_t);
extern void account_process_tick(struct task_struct *, int user);
extern void account_steal_ticks(unsigned long ticks);
extern void account_idle_ticks(unsigned long ticks);
#endif /* _LINUX_KERNEL_STAT_H */