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author | Arjan van de Ven <arjan@infradead.org> | 2009-09-21 17:04:08 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 07:17:45 -0700 |
commit | 69d25870f20c4b2563304f2b79c5300dd60a067e (patch) | |
tree | cda2b2d65c1be95420c6ba92ae2d40fade4232c4 /kernel/sched.c | |
parent | 45d80eea87c9f8292d2d33173d6866c0ec57238a (diff) | |
download | kernel_samsung_smdk4412-69d25870f20c4b2563304f2b79c5300dd60a067e.zip kernel_samsung_smdk4412-69d25870f20c4b2563304f2b79c5300dd60a067e.tar.gz kernel_samsung_smdk4412-69d25870f20c4b2563304f2b79c5300dd60a067e.tar.bz2 |
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/sched.c')
-rw-r--r-- | kernel/sched.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 91843ba..0ac9053 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; |