From 69d25870f20c4b2563304f2b79c5300dd60a067e Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Mon, 21 Sep 2009 17:04:08 -0700 Subject: cpuidle: fix the menu governor to boost IO performance Fix the menu idle governor which balances power savings, energy efficiency and performance impact. The reason for a reworked governor is that there have been serious performance issues reported with the existing code on Nehalem server systems. To show this I'm sure Andrew wants to see benchmark results: (benchmark is "fio", "no cstates" is using "idle=poll") no cstates current linux new algorithm 1 disk 107 Mb/s 85 Mb/s 105 Mb/s 2 disks 215 Mb/s 123 Mb/s 209 Mb/s 12 disks 590 Mb/s 320 Mb/s 585 Mb/s In various power benchmark measurements, no degredation was found by our measurement&diagnostics team. Obviously a small percentage more power was used in the "fio" benchmark, due to the much higher performance. While it would be a novel idea to describe the new algorithm in this commit message, I cheaped out and described it in comments in the code instead. [changes since first post: spelling fixes from akpm, review feedback, folded menu-tng into menu.c] Signed-off-by: Arjan van de Ven Cc: Venkatesh Pallipadi Cc: Len Brown Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Yanmin Zhang Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 17e9a8e9a51d..97b10da0a3ea 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -140,6 +140,10 @@ extern int nr_processes(void); extern unsigned long nr_running(void); extern unsigned long nr_uninterruptible(void); extern unsigned long nr_iowait(void); +extern unsigned long nr_iowait_cpu(void); +extern unsigned long this_cpu_load(void); + + extern void calc_global_load(void); extern u64 cpu_nr_migrations(int cpu); -- cgit v1.2.3