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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2010-10-27 15:34:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-27 18:03:13 -0700
commitf2c66cd8eeddedb440f33bc0f5cec1ed7ae376cb (patch)
tree4b8cfcd2a76652839121707fc2a49b70489ec055 /include/linux/kernel_stat.h
parent19cd56c48da58bebc3a638e036bcab69469acd27 (diff)
downloadlwn-f2c66cd8eeddedb440f33bc0f5cec1ed7ae376cb.tar.gz
lwn-f2c66cd8eeddedb440f33bc0f5cec1ed7ae376cb.zip
/proc/stat: scalability of irq num per cpu
/proc/stat shows the total number of all interrupts to each cpu. But when the number of IRQs are very large, it take very long time and 'cat /proc/stat' takes more than 10 secs. This is because sum of all irq events are counted when /proc/stat is read. This patch adds "sum of all irq" counter percpu and reduce read costs. The cost of reading /proc/stat is important because it's used by major applications as 'top', 'ps', 'w', etc.... A test on a mechin (4096cpu, 256 nodes, 4592 irqs) shows %time cat /proc/stat > /dev/null Before Patch: 12.627 sec After Patch: 2.459 sec 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>
Diffstat (limited to 'include/linux/kernel_stat.h')
-rw-r--r--include/linux/kernel_stat.h14
1 files changed, 12 insertions, 2 deletions
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index c059044bc6dc..8b9b89085530 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -33,6 +33,7 @@ struct kernel_stat {
#ifndef CONFIG_GENERIC_HARDIRQS
unsigned int irqs[NR_IRQS];
#endif
+ unsigned long irqs_sum;
unsigned int softirqs[NR_SOFTIRQS];
};
@@ -54,6 +55,7 @@ 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)
@@ -65,8 +67,9 @@ static inline unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
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) \
- ((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
@@ -94,6 +97,13 @@ static inline unsigned int kstat_irqs(unsigned int irq)
return sum;
}
+/*
+ * 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: