x86 idle: remove mwait_idle() and "idle=mwait" cmdline param
mwait_idle() is a C1-only idle loop intended to be more efficient than HLT, starting on Pentium-4 HT-enabled processors. But mwait_idle() has been replaced by the more general mwait_idle_with_hints(), which handles both C1 and deeper C-states. ACPI processor_idle and intel_idle use only mwait_idle_with_hints(), and no longer use mwait_idle(). Here we simplify the x86 native idle code by removing mwait_idle(), and the "idle=mwait" bootparam used to invoke it. Since Linux 3.0 there has been a boot-time warning when "idle=mwait" was invoked saying it would be removed in 2012. This removal was also noted in the (now removed:-) feature-removal-schedule.txt. After this change, kernels configured with (CONFIG_ACPI=n && CONFIG_INTEL_IDLE=n) when run on hardware that supports MWAIT will simply use HLT. If MWAIT is desired on those systems, cpuidle and the cpuidle drivers above can be enabled. Signed-off-by: Len Brown <len.brown@intel.com> Cc: x86@kernel.org
This commit is contained in:
parent
6a377ddc4e
commit
69fb3676df
5 changed files with 4 additions and 87 deletions
|
@ -1039,16 +1039,11 @@ 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
|
||||
|
|
|
@ -725,7 +725,7 @@ extern unsigned long boot_option_idle_override;
|
|||
extern bool amd_e400_c1e_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);
|
||||
|
|
|
@ -421,27 +421,6 @@ void stop_this_cpu(void *dummy)
|
|||
}
|
||||
}
|
||||
|
||||
/* Default MONITOR/MWAIT with no hints, used for default C1 state */
|
||||
static void mwait_idle(void)
|
||||
{
|
||||
if (!need_resched()) {
|
||||
trace_power_start_rcuidle(POWER_CSTATE, 1, smp_processor_id());
|
||||
trace_cpu_idle_rcuidle(1, smp_processor_id());
|
||||
if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
|
||||
clflush((void *)¤t_thread_info()->flags);
|
||||
|
||||
__monitor((void *)¤t_thread_info()->flags, 0, 0);
|
||||
smp_mb();
|
||||
if (!need_resched())
|
||||
__sti_mwait(0, 0);
|
||||
else
|
||||
local_irq_enable();
|
||||
trace_power_end_rcuidle(smp_processor_id());
|
||||
trace_cpu_idle_rcuidle(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
|
||||
|
@ -458,53 +437,6 @@ static void poll_idle(void)
|
|||
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
|
||||
}
|
||||
|
||||
/*
|
||||
* mwait selection logic:
|
||||
*
|
||||
* It depends on the CPU. For AMD CPUs that support MWAIT this is
|
||||
* wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings
|
||||
* then depend on a clock divisor and current Pstate of the core. If
|
||||
* all cores of a processor are in halt state (C1) the processor can
|
||||
* enter the C1E (C1 enhanced) state. If mwait is used this will never
|
||||
* happen.
|
||||
*
|
||||
* idle=mwait overrides this decision and forces the usage of mwait.
|
||||
*/
|
||||
|
||||
#define MWAIT_INFO 0x05
|
||||
#define MWAIT_ECX_EXTENDED_INFO 0x01
|
||||
#define MWAIT_EDX_C1 0xf0
|
||||
|
||||
int mwait_usable(const struct cpuinfo_x86 *c)
|
||||
{
|
||||
u32 eax, ebx, ecx, edx;
|
||||
|
||||
/* Use mwait if idle=mwait boot option is given */
|
||||
if (boot_option_idle_override == IDLE_FORCE_MWAIT)
|
||||
return 1;
|
||||
|
||||
/*
|
||||
* Any idle= boot option other than idle=mwait means that we must not
|
||||
* use mwait. Eg: idle=halt or idle=poll or idle=nomwait
|
||||
*/
|
||||
if (boot_option_idle_override != IDLE_NO_OVERRIDE)
|
||||
return 0;
|
||||
|
||||
if (c->cpuid_level < MWAIT_INFO)
|
||||
return 0;
|
||||
|
||||
cpuid(MWAIT_INFO, &eax, &ebx, &ecx, &edx);
|
||||
/* Check, whether EDX has extended info about MWAIT */
|
||||
if (!(ecx & MWAIT_ECX_EXTENDED_INFO))
|
||||
return 1;
|
||||
|
||||
/*
|
||||
* edx enumeratios MONITOR/MWAIT extensions. Check, whether
|
||||
* C1 supports MWAIT
|
||||
*/
|
||||
return (edx & MWAIT_EDX_C1);
|
||||
}
|
||||
|
||||
bool amd_e400_c1e_detected;
|
||||
EXPORT_SYMBOL(amd_e400_c1e_detected);
|
||||
|
||||
|
@ -576,13 +508,7 @@ 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
|
||||
*/
|
||||
pr_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 */
|
||||
pr_info("using AMD E400 aware idle routine\n");
|
||||
pm_idle = amd_e400_idle;
|
||||
|
@ -606,9 +532,6 @@ static int __init idle_setup(char *str)
|
|||
pr_info("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 2012\n");
|
||||
} else if (!strcmp(str, "halt")) {
|
||||
/*
|
||||
* When the boot option of idle=halt is added, halt is
|
||||
|
|
|
@ -1369,7 +1369,7 @@ static inline void mwait_play_dead(void)
|
|||
void *mwait_ptr;
|
||||
struct cpuinfo_x86 *c = __this_cpu_ptr(&cpu_info);
|
||||
|
||||
if (!(this_cpu_has(X86_FEATURE_MWAIT) && mwait_usable(c)))
|
||||
if (!this_cpu_has(X86_FEATURE_MWAIT))
|
||||
return;
|
||||
if (!this_cpu_has(X86_FEATURE_CLFLSH))
|
||||
return;
|
||||
|
|
|
@ -84,7 +84,6 @@ static DEFINE_PER_CPU(struct cpuidle_device *, acpi_cpuidle_device);
|
|||
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;
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in a new issue