diff options
author | Ingo Molnar <mingo@elte.hu> | 2008-05-14 02:47:40 -0400 |
---|---|---|
committer | Thomas Gleixner <tglx@linutronix.de> | 2008-05-17 16:57:20 -0400 |
commit | a738d897b7b03b83488ae74a9bc03d26a2875dc6 (patch) | |
tree | a5eadb80fb893a36d3653fd9cfc0ba5acaa0e30b /arch/x86 | |
parent | f26a3988917913b3d11b2bd741601a2c64ab9204 (diff) |
x86: remove mwait capability C-state check
Vegard Nossum reports:
| powertop shows between 200-400 wakeups/second with the description
| "<kernel IPI>: Rescheduling interrupts" when all processors have load (e.g.
| I need to run two busy-loops on my 2-CPU system for this to show up).
|
| The bisect resulted in this commit:
|
| commit 0c07ee38c9d4eb081758f5ad14bbffa7197e1aec
| Date: Wed Jan 30 13:33:16 2008 +0100
|
| x86: use the correct cpuid method to detect MWAIT support for C states
remove the functional effects of this patch and make mwait unconditional.
A future patch will turn off mwait on specific CPUs where that causes
power to be wasted.
Bisected-by: Vegard Nossum <vegard.nossum@gmail.com>
Tested-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86')
-rw-r--r-- | arch/x86/kernel/process.c | 11 |
1 files changed, 1 insertions, 10 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 67e9b4a1e89d..c7b6a694ca22 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c | |||
@@ -99,15 +99,6 @@ static void mwait_idle(void) | |||
99 | local_irq_enable(); | 99 | local_irq_enable(); |
100 | } | 100 | } |
101 | 101 | ||
102 | |||
103 | static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c) | ||
104 | { | ||
105 | if (force_mwait) | ||
106 | return 1; | ||
107 | /* Any C1 states supported? */ | ||
108 | return c->cpuid_level >= 5 && ((cpuid_edx(5) >> 4) & 0xf) > 0; | ||
109 | } | ||
110 | |||
111 | /* | 102 | /* |
112 | * On SMP it's slightly faster (but much more power-consuming!) | 103 | * On SMP it's slightly faster (but much more power-consuming!) |
113 | * to poll the ->work.need_resched flag instead of waiting for the | 104 | * to poll the ->work.need_resched flag instead of waiting for the |
@@ -131,7 +122,7 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) | |||
131 | " performance may degrade.\n"); | 122 | " performance may degrade.\n"); |
132 | } | 123 | } |
133 | #endif | 124 | #endif |
134 | if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) { | 125 | if (cpu_has(c, X86_FEATURE_MWAIT)) { |
135 | /* | 126 | /* |
136 | * Skip, if setup has overridden idle. | 127 | * Skip, if setup has overridden idle. |
137 | * One CPU supports mwait => All CPUs supports mwait | 128 | * One CPU supports mwait => All CPUs supports mwait |