Commit 32e95180 authored by Len Brown's avatar Len Brown
Browse files

intel_idle: export both C1 and C1E 



Here we disable HW promotion of C1 to C1E
and export both C1 and C1E and distinct C-states.

This allows a cpuidle governor to choose a lower latency
C-state than C1E when necessary to satisfy performance
and QOS constraints -- and still save power versus polling.
This also corrects the erroneous latency previously reported
for C1E -- it is 10usec, not 1usec.

Note that if you use "intel_idle.max_cstate=N",
then you must increment N by 1 to get the same behavior
after this change.

Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent e022e7eb

drivers/idle/intel_idle.c

+49 −5
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ struct idle_cpu { 
	 * Indicate which enable bits to clear here.

	 */

	unsigned long auto_demotion_disable_flags;

	bool disable_promotion_to_c1e;

};



static const struct idle_cpu *icpu;
@@ -131,6 +132,13 @@ static struct cpuidle_state nehalem_cstates[CPUIDLE_STATE_MAX] = { 
		.exit_latency = 3,

		.target_residency = 6,

		.enter = &intel_idle },

	{

		.name = "C1E-NHM",

		.desc = "MWAIT 0x01",

		.flags = MWAIT2flg(0x01) | CPUIDLE_FLAG_TIME_VALID,

		.exit_latency = 10,

		.target_residency = 20,

		.enter = &intel_idle },

	{

		.name = "C3-NHM",

		.desc = "MWAIT 0x10",
@@ -154,8 +162,15 @@ static struct cpuidle_state snb_cstates[CPUIDLE_STATE_MAX] = { 
		.name = "C1-SNB",

		.desc = "MWAIT 0x00",

		.flags = MWAIT2flg(0x00) | CPUIDLE_FLAG_TIME_VALID,

		.exit_latency = 1,

		.target_residency = 1,

		.exit_latency = 2,

		.target_residency = 2,

		.enter = &intel_idle },

	{

		.name = "C1E-SNB",

		.desc = "MWAIT 0x01",

		.flags = MWAIT2flg(0x01) | CPUIDLE_FLAG_TIME_VALID,

		.exit_latency = 10,

		.target_residency = 20,

		.enter = &intel_idle },

	{

		.name = "C3-SNB",
@@ -190,6 +205,13 @@ static struct cpuidle_state ivb_cstates[CPUIDLE_STATE_MAX] = { 
		.exit_latency = 1,

		.target_residency = 1,

		.enter = &intel_idle },

	{

		.name = "C1E-IVB",

		.desc = "MWAIT 0x01",

		.flags = MWAIT2flg(0x01) | CPUIDLE_FLAG_TIME_VALID,

		.exit_latency = 10,

		.target_residency = 20,

		.enter = &intel_idle },

	{

		.name = "C3-IVB",

		.desc = "MWAIT 0x10",
@@ -223,6 +245,13 @@ static struct cpuidle_state hsw_cstates[CPUIDLE_STATE_MAX] = { 
		.exit_latency = 2,

		.target_residency = 2,

		.enter = &intel_idle },

	{

		.name = "C1E-HSW",

		.desc = "MWAIT 0x01",

		.flags = MWAIT2flg(0x01) | CPUIDLE_FLAG_TIME_VALID,

		.exit_latency = 10,

		.target_residency = 20,

		.enter = &intel_idle },

	{

		.name = "C3-HSW",

		.desc = "MWAIT 0x10",
@@ -250,11 +279,11 @@ static struct cpuidle_state hsw_cstates[CPUIDLE_STATE_MAX] = { 


static struct cpuidle_state atom_cstates[CPUIDLE_STATE_MAX] = {

	{

		.name = "C1-ATM",

		.name = "C1E-ATM",

		.desc = "MWAIT 0x00",

		.flags = MWAIT2flg(0x00) | CPUIDLE_FLAG_TIME_VALID,

		.exit_latency = 1,

		.target_residency = 4,

		.exit_latency = 10,

		.target_residency = 20,

		.enter = &intel_idle },

	{

		.name = "C2-ATM",
@@ -377,10 +406,19 @@ static void auto_demotion_disable(void *dummy) 
	msr_bits &= ~(icpu->auto_demotion_disable_flags);

	wrmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);

}

static void c1e_promotion_disable(void *dummy)

{

	unsigned long long msr_bits;



	rdmsrl(MSR_IA32_POWER_CTL, msr_bits);

	msr_bits &= ~0x2;

	wrmsrl(MSR_IA32_POWER_CTL, msr_bits);

}



static const struct idle_cpu idle_cpu_nehalem = {

	.state_table = nehalem_cstates,

	.auto_demotion_disable_flags = NHM_C1_AUTO_DEMOTE | NHM_C3_AUTO_DEMOTE,

	.disable_promotion_to_c1e = true,

};



static const struct idle_cpu idle_cpu_atom = {
@@ -394,14 +432,17 @@ static const struct idle_cpu idle_cpu_lincroft = { 


static const struct idle_cpu idle_cpu_snb = {

	.state_table = snb_cstates,

	.disable_promotion_to_c1e = true,

};



static const struct idle_cpu idle_cpu_ivb = {

	.state_table = ivb_cstates,

	.disable_promotion_to_c1e = true,

};



static const struct idle_cpu idle_cpu_hsw = {

	.state_table = hsw_cstates,

	.disable_promotion_to_c1e = true,

};



#define ICPU(model, cpu) \
@@ -544,6 +585,9 @@ static int intel_idle_cpuidle_driver_init(void) 
	if (icpu->auto_demotion_disable_flags)

		on_each_cpu(auto_demotion_disable, NULL, 1);



	if (icpu->disable_promotion_to_c1e)	/* each-cpu is redundant */

		on_each_cpu(c1e_promotion_disable, NULL, 1);



	return 0;

}

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