diff options
| author |   KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2010-10-27 15:34:15 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-27 18:03:13 -0700 |
| commit | 478735e38887077ac77a9756121b6ce0cb956e2f (patch) | |
| tree | 7b42110f71b1711f56cbbc0a01f00894b221337d /include/linux/kernel_stat.h | |
| parent | /proc/stat: scalability of irq num per cpu (diff) | |
| download | wireguard-linux-478735e38887077ac77a9756121b6ce0cb956e2f.tar.xz wireguard-linux-478735e38887077ac77a9756121b6ce0cb956e2f.zip | |
/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>
Diffstat (limited to 'include/linux/kernel_stat.h')
| -rw-r--r-- | include/linux/kernel_stat.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h index 8b9b89085530..ad54c846911b 100644 --- a/include/linux/kernel_stat.h +++ b/include/linux/kernel_stat.h @@ -86,6 +86,7 @@ static inline unsigned int kstat_softirqs_cpu(unsigned int irq, int cpu) /* * 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; @@ -96,6 +97,9 @@ static inline unsigned int kstat_irqs(unsigned int irq) return sum; } +#else +extern unsigned int kstat_irqs(unsigned int irq); +#endif /* * Number of interrupts per cpu, since bootup |