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authorArjan van de Ven <arjan@infradead.org>2009-09-21 17:04:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 07:17:45 -0700
commit69d25870f20c4b2563304f2b79c5300dd60a067e (patch)
treecda2b2d65c1be95420c6ba92ae2d40fade4232c4 /kernel
parent45d80eea87c9f8292d2d33173d6866c0ec57238a (diff)
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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 <arjan@linux.intel.com> Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Len Brown <lenb@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Yanmin Zhang <yanmin_zhang@linux.intel.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 91843ba7f23..0ac9053c21d 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2904,6 +2904,19 @@ unsigned long nr_iowait(void)
return sum;
}
+unsigned long nr_iowait_cpu(void)
+{
+ struct rq *this = this_rq();
+ return atomic_read(&this->nr_iowait);
+}
+
+unsigned long this_cpu_load(void)
+{
+ struct rq *this = this_rq();
+ return this->cpu_load[0];
+}
+
+
/* Variables and functions for calc_load */
static atomic_long_t calc_load_tasks;
static unsigned long calc_load_update;