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
..
array.c
base.c	signals: move cred_guard_mutex from task_struct to signal_struct	2010-10-27 18:03:12 -07:00
cmdline.c
cpuinfo.c
devices.c
generic.c
inode.c	bkl: Remove locked .ioctl file operation	2010-08-14 00:24:24 +02:00
internal.h
interrupts.c
Kconfig	vmcore: it is not experimental any more	2010-10-26 16:52:05 -07:00
kcore.c
kmsg.c
loadavg.c
Makefile	procfs: simplify conditional processing of fs/proc.o.	2010-08-11 08:59:20 -07:00
meminfo.c
mmu.c
nommu.c
page.c	proc: export uncached bit properly in /proc/kpageflags	2010-09-09 18:57:23 -07:00
proc_devtree.c
proc_net.c
proc_sysctl.c	fs: do not assign default i_ino in new_inode	2010-10-25 21:26:11 -04:00
proc_tty.c	Revert "tty: Add a new file /proc/tty/consoles"	2010-10-23 08:14:12 -07:00
root.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
softirqs.c	procfs: fix /proc/softirqs formatting	2010-10-27 18:03:13 -07:00
stat.c	/proc/stat: fix scalability of irq sum of all cpu	2010-10-27 18:03:13 -07:00
task_mmu.c	/proc/pid/smaps: export amount of anonymous memory in a mapping	2010-10-27 18:03:13 -07:00
task_nommu.c
uptime.c
version.c
vmcore.c	/proc/vmcore: fix seeking	2010-09-22 17:22:38 -07:00