On Mon, 19 Sept 2022 at 12:18, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
Doing RCU-idle outside the driver, only to then temporarily enable it
again before going idle is daft.
Notably: this converts all dt_init_idle_driver() and
__CPU_PM_CPU_IDLE_ENTER() users for they are inextrably intertwined.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Kind regards
Uffe
---
arch/arm/mach-omap2/cpuidle34xx.c | 4 ++--
drivers/acpi/processor_idle.c | 2 ++
drivers/cpuidle/cpuidle-arm.c | 1 +
drivers/cpuidle/cpuidle-big_little.c | 8 ++++++--
drivers/cpuidle/cpuidle-psci.c | 1 +
drivers/cpuidle/cpuidle-qcom-spm.c | 1 +
drivers/cpuidle/cpuidle-riscv-sbi.c | 1 +
drivers/cpuidle/dt_idle_states.c | 2 +-
include/linux/cpuidle.h | 4 ++++
9 files changed, 19 insertions(+), 5 deletions(-)
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1200,6 +1200,8 @@ static int acpi_processor_setup_lpi_stat
state->target_residency = lpi->min_residency;
if (lpi->arch_flags)
state->flags |= CPUIDLE_FLAG_TIMER_STOP;
+ if (lpi->entry_method == ACPI_CSTATE_FFH)
+ state->flags |= CPUIDLE_FLAG_RCU_IDLE;
I assume the state index here will never be 0?
If not, it may lead to that acpi_processor_ffh_lpi_enter() may trigger
CPU_PM_CPU_IDLE_ENTER_PARAM() to call ct_cpuidle_enter|exit() for an
idle-state that doesn't have the CPUIDLE_FLAG_RCU_IDLE bit set.
state->enter = acpi_idle_lpi_enter;
drv->safe_state_index = i;
}
--- a/drivers/cpuidle/cpuidle-arm.c
+++ b/drivers/cpuidle/cpuidle-arm.c
@@ -53,6 +53,7 @@ static struct cpuidle_driver arm_idle_dr
* handler for idle state index 0.
*/
.states[0] = {
+ .flags = CPUIDLE_FLAG_RCU_IDLE,
Comparing arm64 and arm32 idle-states/idle-drivers, the $subject
series ends up setting the CPUIDLE_FLAG_RCU_IDLE for the ARM WFI idle
state (state zero), but only for the arm64 and psci cases (mostly
arm64). For arm32 we would need to update the ARM_CPUIDLE_WFI_STATE
too, as that is what most arm32 idle-drivers are using. My point is,
the code becomes a bit inconsistent.
Perhaps it's easier to avoid setting the CPUIDLE_FLAG_RCU_IDLE bit for
all of the ARM WFI idle states, for both arm64 and arm32?
.enter = arm_enter_idle_state,
.exit_latency = 1,
.target_residency = 1,
--- a/drivers/cpuidle/cpuidle-big_little.c
+++ b/drivers/cpuidle/cpuidle-big_little.c
@@ -64,7 +64,8 @@ static struct cpuidle_driver bl_idle_lit
.enter = bl_enter_powerdown,
.exit_latency = 700,
.target_residency = 2500,
- .flags = CPUIDLE_FLAG_TIMER_STOP,
+ .flags = CPUIDLE_FLAG_TIMER_STOP |
+ CPUIDLE_FLAG_RCU_IDLE,
.name = "C1",
.desc = "ARM little-cluster power down",
},
@@ -85,7 +86,8 @@ static struct cpuidle_driver bl_idle_big
.enter = bl_enter_powerdown,
.exit_latency = 500,
.target_residency = 2000,
- .flags = CPUIDLE_FLAG_TIMER_STOP,
+ .flags = CPUIDLE_FLAG_TIMER_STOP |
+ CPUIDLE_FLAG_RCU_IDLE,
.name = "C1",
.desc = "ARM big-cluster power down",
},
@@ -124,11 +126,13 @@ static int bl_enter_powerdown(struct cpu
struct cpuidle_driver *drv, int idx)
{
cpu_pm_enter();
+ ct_idle_enter();
cpu_suspend(0, bl_powerdown_finisher);
/* signals the MCPM core that CPU is out of low power state */
mcpm_cpu_powered_up();
+ ct_idle_exit();
cpu_pm_exit();
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -357,6 +357,7 @@ static int psci_idle_init_cpu(struct dev
* PSCI idle states relies on architectural WFI to be represented as
* state index 0.
*/
+ drv->states[0].flags = CPUIDLE_FLAG_RCU_IDLE;
drv->states[0].enter = psci_enter_idle_state;
drv->states[0].exit_latency = 1;
drv->states[0].target_residency = 1;
--- a/drivers/cpuidle/cpuidle-qcom-spm.c
+++ b/drivers/cpuidle/cpuidle-qcom-spm.c
@@ -72,6 +72,7 @@ static struct cpuidle_driver qcom_spm_id
.owner = THIS_MODULE,
.states[0] = {
.enter = spm_enter_idle_state,
+ .flags = CPUIDLE_FLAG_RCU_IDLE,
.exit_latency = 1,
.target_residency = 1,
.power_usage = UINT_MAX,
--- a/drivers/cpuidle/cpuidle-riscv-sbi.c
+++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
@@ -332,6 +332,7 @@ static int sbi_cpuidle_init_cpu(struct d
drv->cpumask = (struct cpumask *)cpumask_of(cpu);
/* RISC-V architectural WFI to be represented as state index 0. */
+ drv->states[0].flags = CPUIDLE_FLAG_RCU_IDLE;
drv->states[0].enter = sbi_cpuidle_enter_state;
drv->states[0].exit_latency = 1;
drv->states[0].target_residency = 1;
--- a/drivers/cpuidle/dt_idle_states.c
+++ b/drivers/cpuidle/dt_idle_states.c
@@ -77,7 +77,7 @@ static int init_state_node(struct cpuidl
if (err)
desc = state_node->name;
- idle_state->flags = 0;
+ idle_state->flags = CPUIDLE_FLAG_RCU_IDLE;
if (of_property_read_bool(state_node, "local-timer-stop"))
idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
/*
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -282,14 +282,18 @@ extern s64 cpuidle_governor_latency_req(
int __ret = 0; \
\
if (!idx) { \
+ ct_idle_enter(); \
According to my comment above, we should then drop these calls to
ct_idle_enter and ct_idle_exit() here. Right?
cpu_do_idle(); \
+ ct_idle_exit(); \
return idx; \
} \
\
if (!is_retention) \
__ret = cpu_pm_enter(); \
if (!__ret) { \
+ ct_idle_enter(); \
__ret = low_level_idle_enter(state); \
+ ct_idle_exit(); \
if (!is_retention) \
cpu_pm_exit(); \
} \
Kind regards
Uffe
