diff options
| author | Arjan van de Ven <arjan@infradead.org> | 2009-09-21 17:04:08 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 07:17:45 -0700 |
| commit | 69d25870f20c4b2563304f2b79c5300dd60a067e (patch) | |
| tree | cda2b2d65c1be95420c6ba92ae2d40fade4232c4 /include/linux/sched.h | |
| parent | 45d80eea87c9f8292d2d33173d6866c0ec57238a (diff) | |
| download | lwn-69d25870f20c4b2563304f2b79c5300dd60a067e.tar.gz lwn-69d25870f20c4b2563304f2b79c5300dd60a067e.zip | |
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 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 4 |
1 files changed, 4 insertions, 0 deletions
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); |