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Subject[PATCH 18/18] 2.6.40: x86 idle: remove deprecated mwait_idle()
Date
From: Len Brown <len.brown@intel.com>

For ACPI mode, mwait_with_hints() in cstate.c is used instead of
mwait_idle().

For INTEL_IDLE mode, the mwait in intel_idle() is used instead of
mwait_idle().

So mwait_idle() is used only on hardware that supports MWAIT,
but is running a !ACPI && !INTEL_IDLE kernel.
Such a system will run HLT instead of MWAIT after this change.

cc: x86@kernel.org
Acked-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Len Brown <len.brown@intel.com>
---
Documentation/feature-removal-schedule.txt | 7 -----
Documentation/kernel-parameters.txt | 7 +----
arch/x86/include/asm/processor.h | 2 +-
arch/x86/kernel/process.c | 35 +---------------------------
drivers/acpi/processor_idle.c | 1 -
5 files changed, 3 insertions(+), 49 deletions(-)

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 9b84b1a..f55ba2c 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -6,13 +6,6 @@ be removed from this file.

----------------------------

-What: x86 "idle=mwait" cmdline param
-When: 2.6.40
-Why: simplify x86 idle code
-Who: Len Brown <len.brown@intel.com>
-
-----------------------------
-
What: PRISM54
When: 2.6.34

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a9db94e..52c956a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -920,16 +920,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Claim all unknown PCI IDE storage controllers.

idle= [X86]
- Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
+ Format: idle=poll, idle=halt, idle=nomwait
Poll forces a polling idle loop that can slightly
improve the performance of waking up a idle CPU, but
will use a lot of power and make the system run hot.
Not recommended.
- idle=mwait: On systems which support MONITOR/MWAIT but
- the kernel chose to not use it because it doesn't save
- as much power as a normal idle loop, use the
- MONITOR/MWAIT idle loop anyways. Performance should be
- the same as idle=poll.
idle=halt: Halt is forced to be used for CPU idle.
In such case C2/C3 won't be used again.
idle=nomwait: Disable mwait for CPU C-states
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 10cdee8..3424009 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -752,7 +752,7 @@ extern unsigned long boot_option_idle_override;
extern bool amd_e400_detected;

enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
- IDLE_POLL, IDLE_FORCE_MWAIT};
+ IDLE_POLL};

extern void enable_sep_cpu(void);
extern int sysenter_setup(void);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 8daa323..4ab4bba 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -399,27 +399,6 @@ void cpu_idle_wait(void)
}
EXPORT_SYMBOL_GPL(cpu_idle_wait);

-/* Default MONITOR/MWAIT with no hints, used for default C1 state */
-static void mwait_idle(void)
-{
- if (!need_resched()) {
- trace_power_start(POWER_CSTATE, 1, smp_processor_id());
- trace_cpu_idle(1, smp_processor_id());
- if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
- clflush((void *)&current_thread_info()->flags);
-
- __monitor((void *)&current_thread_info()->flags, 0, 0);
- smp_mb();
- if (!need_resched())
- __sti_mwait(0, 0);
- else
- local_irq_enable();
- trace_power_end(smp_processor_id());
- trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
- } else
- local_irq_enable();
-}
-
/*
* On SMP it's slightly faster (but much more power-consuming!)
* to poll the ->work.need_resched flag instead of waiting for the
@@ -457,9 +436,6 @@ int mwait_usable(const struct cpuinfo_x86 *c)
{
u32 eax, ebx, ecx, edx;

- if (boot_option_idle_override == IDLE_FORCE_MWAIT)
- return 1;
-
if (c->cpuid_level < MWAIT_INFO)
return 0;

@@ -548,13 +524,7 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
if (pm_idle)
return;

- if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
- /*
- * One CPU supports mwait => All CPUs supports mwait
- */
- printk(KERN_INFO "using mwait in idle threads.\n");
- pm_idle = mwait_idle;
- } else if (cpu_has_amd_erratum(amd_erratum_400)) {
+ if (cpu_has_amd_erratum(amd_erratum_400)) {
/* E400: APIC timer interrupt does not wake up CPU from C1e */
printk(KERN_INFO "using E400 aware idle routine\n");
pm_idle = amd_e400_idle;
@@ -578,9 +548,6 @@ static int __init idle_setup(char *str)
printk("using polling idle threads.\n");
pm_idle = poll_idle;
boot_option_idle_override = IDLE_POLL;
- } else if (!strcmp(str, "mwait")) {
- boot_option_idle_override = IDLE_FORCE_MWAIT;
- WARN_ONCE(1, "\idle=mwait\" will be removed in 2.6.40\"\n");
} else if (!strcmp(str, "halt")) {
/*
* When the boot option of idle=halt is added, halt is
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 53d9f10..954a9d3 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -82,7 +82,6 @@ module_param(latency_factor, uint, 0644);
static int disabled_by_idle_boot_param(void)
{
return boot_option_idle_override == IDLE_POLL ||
- boot_option_idle_override == IDLE_FORCE_MWAIT ||
boot_option_idle_override == IDLE_HALT;
}

--
1.7.5.rc0


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