--- /dev/null
+Guest halt polling
+==================
+
+The cpuidle_haltpoll driver, with the haltpoll governor, allows
+the guest vcpus to poll for a specified amount of time before
+halting.
+This provides the following benefits to host side polling:
+
+ 1) The POLL flag is set while polling is performed, which allows
+ a remote vCPU to avoid sending an IPI (and the associated
+ cost of handling the IPI) when performing a wakeup.
+
+ 2) The VM-exit cost can be avoided.
+
+The downside of guest side polling is that polling is performed
+even with other runnable tasks in the host.
+
+The basic logic as follows: A global value, guest_halt_poll_ns,
+is configured by the user, indicating the maximum amount of
+time polling is allowed. This value is fixed.
+
+Each vcpu has an adjustable guest_halt_poll_ns
+("per-cpu guest_halt_poll_ns"), which is adjusted by the algorithm
+in response to events (explained below).
+
+Module Parameters
+=================
+
+The haltpoll governor has 5 tunable module parameters:
+
+1) guest_halt_poll_ns:
+Maximum amount of time, in nanoseconds, that polling is
+performed before halting.
+
+Default: 200000
+
+2) guest_halt_poll_shrink:
+Division factor used to shrink per-cpu guest_halt_poll_ns when
+wakeup event occurs after the global guest_halt_poll_ns.
+
+Default: 2
+
+3) guest_halt_poll_grow:
+Multiplication factor used to grow per-cpu guest_halt_poll_ns
+when event occurs after per-cpu guest_halt_poll_ns
+but before global guest_halt_poll_ns.
+
+Default: 2
+
+4) guest_halt_poll_grow_start:
+The per-cpu guest_halt_poll_ns eventually reaches zero
+in case of an idle system. This value sets the initial
+per-cpu guest_halt_poll_ns when growing. This can
+be increased from 10000, to avoid misses during the initial
+growth stage:
+
+10k, 20k, 40k, ... (example assumes guest_halt_poll_grow=2).
+
+Default: 50000
+
+5) guest_halt_poll_allow_shrink:
+
+Bool parameter which allows shrinking. Set to N
+to avoid it (per-cpu guest_halt_poll_ns will remain
+high once achieves global guest_halt_poll_ns value).
+
+Default: Y
+
+The module parameters can be set from the debugfs files in:
+
+ /sys/module/haltpoll/parameters/
+
+Further Notes
+=============
+
+- Care should be taken when setting the guest_halt_poll_ns parameter as a
+large value has the potential to drive the cpu usage to 100% on a machine which
+would be almost entirely idle otherwise.
bool "KVM Guest support (including kvmclock)"
depends on PARAVIRT
select PARAVIRT_CLOCK
+ select ARCH_CPUIDLE_HALTPOLL
default y
---help---
This option enables various optimizations for running under the KVM
underlying device model, the host provides the guest with
timing infrastructure such as time of day, and system time
+config ARCH_CPUIDLE_HALTPOLL
+ def_bool n
+ prompt "Disable host haltpoll when loading haltpoll driver"
+ help
+ If virtualized under KVM, disable host haltpoll.
+
config PVH
bool "Support for running PVH guests"
---help---
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ARCH_HALTPOLL_H
+#define _ARCH_HALTPOLL_H
+
+void arch_haltpoll_enable(unsigned int cpu);
+void arch_haltpoll_disable(unsigned int cpu);
+
+#endif
{
return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
}
+EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
static uint32_t __init kvm_detect(void)
{
}
#endif /* CONFIG_PARAVIRT_SPINLOCKS */
+
+#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
+
+static void kvm_disable_host_haltpoll(void *i)
+{
+ wrmsrl(MSR_KVM_POLL_CONTROL, 0);
+}
+
+static void kvm_enable_host_haltpoll(void *i)
+{
+ wrmsrl(MSR_KVM_POLL_CONTROL, 1);
+}
+
+void arch_haltpoll_enable(unsigned int cpu)
+{
+ if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
+ pr_err_once("kvm: host does not support poll control\n");
+ pr_err_once("kvm: host upgrade recommended\n");
+ return;
+ }
+
+ /* Enable guest halt poll disables host halt poll */
+ smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
+}
+EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
+
+void arch_haltpoll_disable(unsigned int cpu)
+{
+ if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
+ return;
+
+ /* Enable guest halt poll disables host halt poll */
+ smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
+}
+EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
+#endif
safe_halt();
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
}
-#ifdef CONFIG_APM_MODULE
+#if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE)
EXPORT_SYMBOL(default_idle);
#endif
Some workloads benefit from using it and it generally should be safe
to use. Say Y here if you are not happy with the alternatives.
+config CPU_IDLE_GOV_HALTPOLL
+ bool "Haltpoll governor (for virtualized systems)"
+ depends on KVM_GUEST
+ help
+ This governor implements haltpoll idle state selection, to be
+ used in conjunction with the haltpoll cpuidle driver, allowing
+ for polling for a certain amount of time before entering idle
+ state.
+
+ Some virtualized workloads benefit from using it.
+
config DT_IDLE_STATES
bool
source "drivers/cpuidle/Kconfig.powerpc"
endmenu
+config HALTPOLL_CPUIDLE
+ tristate "Halt poll cpuidle driver"
+ depends on X86 && KVM_GUEST
+ default y
+ help
+ This option enables halt poll cpuidle driver, which allows to poll
+ before halting in the guest (more efficient than polling in the
+ host via halt_poll_ns for some scenarios).
+
endif
config ARCH_NEEDS_CPU_IDLE_COUPLED
obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
obj-$(CONFIG_DT_IDLE_STATES) += dt_idle_states.o
obj-$(CONFIG_ARCH_HAS_CPU_RELAX) += poll_state.o
+obj-$(CONFIG_HALTPOLL_CPUIDLE) += cpuidle-haltpoll.o
##################################################################################
# ARM SoC drivers
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * cpuidle driver for haltpoll governor.
+ *
+ * Copyright 2019 Red Hat, Inc. and/or its affiliates.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ *
+ * Authors: Marcelo Tosatti <mtosatti@redhat.com>
+ */
+
+#include <linux/init.h>
+#include <linux/cpu.h>
+#include <linux/cpuidle.h>
+#include <linux/module.h>
+#include <linux/sched/idle.h>
+#include <linux/kvm_para.h>
+#include <linux/cpuidle_haltpoll.h>
+
+static struct cpuidle_device __percpu *haltpoll_cpuidle_devices;
+static enum cpuhp_state haltpoll_hp_state;
+
+static int default_enter_idle(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ if (current_clr_polling_and_test()) {
+ local_irq_enable();
+ return index;
+ }
+ default_idle();
+ return index;
+}
+
+static struct cpuidle_driver haltpoll_driver = {
+ .name = "haltpoll",
+ .governor = "haltpoll",
+ .states = {
+ { /* entry 0 is for polling */ },
+ {
+ .enter = default_enter_idle,
+ .exit_latency = 1,
+ .target_residency = 1,
+ .power_usage = -1,
+ .name = "haltpoll idle",
+ .desc = "default architecture idle",
+ },
+ },
+ .safe_state_index = 0,
+ .state_count = 2,
+};
+
+static int haltpoll_cpu_online(unsigned int cpu)
+{
+ struct cpuidle_device *dev;
+
+ dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
+ if (!dev->registered) {
+ dev->cpu = cpu;
+ if (cpuidle_register_device(dev)) {
+ pr_notice("cpuidle_register_device %d failed!\n", cpu);
+ return -EIO;
+ }
+ arch_haltpoll_enable(cpu);
+ }
+
+ return 0;
+}
+
+static int haltpoll_cpu_offline(unsigned int cpu)
+{
+ struct cpuidle_device *dev;
+
+ dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
+ if (dev->registered) {
+ arch_haltpoll_disable(cpu);
+ cpuidle_unregister_device(dev);
+ }
+
+ return 0;
+}
+
+static void haltpoll_uninit(void)
+{
+ if (haltpoll_hp_state)
+ cpuhp_remove_state(haltpoll_hp_state);
+ cpuidle_unregister_driver(&haltpoll_driver);
+
+ free_percpu(haltpoll_cpuidle_devices);
+ haltpoll_cpuidle_devices = NULL;
+}
+
+static int __init haltpoll_init(void)
+{
+ int ret;
+ struct cpuidle_driver *drv = &haltpoll_driver;
+
+ cpuidle_poll_state_init(drv);
+
+ if (!kvm_para_available() ||
+ !kvm_para_has_hint(KVM_HINTS_REALTIME))
+ return -ENODEV;
+
+ ret = cpuidle_register_driver(drv);
+ if (ret < 0)
+ return ret;
+
+ haltpoll_cpuidle_devices = alloc_percpu(struct cpuidle_device);
+ if (haltpoll_cpuidle_devices == NULL) {
+ cpuidle_unregister_driver(drv);
+ return -ENOMEM;
+ }
+
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "cpuidle/haltpoll:online",
+ haltpoll_cpu_online, haltpoll_cpu_offline);
+ if (ret < 0) {
+ haltpoll_uninit();
+ } else {
+ haltpoll_hp_state = ret;
+ ret = 0;
+ }
+
+ return ret;
+}
+
+static void __exit haltpoll_exit(void)
+{
+ haltpoll_uninit();
+}
+
+module_init(haltpoll_init);
+module_exit(haltpoll_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");
cpuidle_curr_governor->reflect(dev, index);
}
+/**
+ * cpuidle_poll_time - return amount of time to poll for,
+ * governors can override dev->poll_limit_ns if necessary
+ *
+ * @drv: the cpuidle driver tied with the cpu
+ * @dev: the cpuidle device
+ *
+ */
+u64 cpuidle_poll_time(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev)
+{
+ int i;
+ u64 limit_ns;
+
+ if (dev->poll_limit_ns)
+ return dev->poll_limit_ns;
+
+ limit_ns = TICK_NSEC;
+ for (i = 1; i < drv->state_count; i++) {
+ if (drv->states[i].disabled || dev->states_usage[i].disable)
+ continue;
+
+ limit_ns = (u64)drv->states[i].target_residency * NSEC_PER_USEC;
+ }
+
+ dev->poll_limit_ns = limit_ns;
+
+ return dev->poll_limit_ns;
+}
+
/**
* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
*/
/* For internal use only */
extern char param_governor[];
extern struct cpuidle_governor *cpuidle_curr_governor;
+extern struct cpuidle_governor *cpuidle_prev_governor;
extern struct list_head cpuidle_governors;
extern struct list_head cpuidle_detected_devices;
extern struct mutex cpuidle_lock;
extern void cpuidle_uninstall_idle_handler(void);
/* governors */
+extern struct cpuidle_governor *cpuidle_find_governor(const char *str);
extern int cpuidle_switch_governor(struct cpuidle_governor *gov);
/* sysfs */
*/
int cpuidle_register_driver(struct cpuidle_driver *drv)
{
+ struct cpuidle_governor *gov;
int ret;
spin_lock(&cpuidle_driver_lock);
ret = __cpuidle_register_driver(drv);
spin_unlock(&cpuidle_driver_lock);
+ if (!ret && !strlen(param_governor) && drv->governor &&
+ (cpuidle_get_driver() == drv)) {
+ mutex_lock(&cpuidle_lock);
+ gov = cpuidle_find_governor(drv->governor);
+ if (gov) {
+ cpuidle_prev_governor = cpuidle_curr_governor;
+ if (cpuidle_switch_governor(gov) < 0)
+ cpuidle_prev_governor = NULL;
+ }
+ mutex_unlock(&cpuidle_lock);
+ }
+
return ret;
}
EXPORT_SYMBOL_GPL(cpuidle_register_driver);
*/
void cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
+ bool enabled = (cpuidle_get_driver() == drv);
+
spin_lock(&cpuidle_driver_lock);
__cpuidle_unregister_driver(drv);
spin_unlock(&cpuidle_driver_lock);
+
+ if (!enabled)
+ return;
+
+ mutex_lock(&cpuidle_lock);
+ if (cpuidle_prev_governor) {
+ if (!cpuidle_switch_governor(cpuidle_prev_governor))
+ cpuidle_prev_governor = NULL;
+ }
+ mutex_unlock(&cpuidle_lock);
}
EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
LIST_HEAD(cpuidle_governors);
struct cpuidle_governor *cpuidle_curr_governor;
+struct cpuidle_governor *cpuidle_prev_governor;
/**
- * __cpuidle_find_governor - finds a governor of the specified name
+ * cpuidle_find_governor - finds a governor of the specified name
* @str: the name
*
* Must be called with cpuidle_lock acquired.
*/
-static struct cpuidle_governor * __cpuidle_find_governor(const char *str)
+struct cpuidle_governor *cpuidle_find_governor(const char *str)
{
struct cpuidle_governor *gov;
return -ENODEV;
mutex_lock(&cpuidle_lock);
- if (__cpuidle_find_governor(gov->name) == NULL) {
+ if (cpuidle_find_governor(gov->name) == NULL) {
ret = 0;
list_add_tail(&gov->governor_list, &cpuidle_governors);
if (!cpuidle_curr_governor ||
obj-$(CONFIG_CPU_IDLE_GOV_LADDER) += ladder.o
obj-$(CONFIG_CPU_IDLE_GOV_MENU) += menu.o
obj-$(CONFIG_CPU_IDLE_GOV_TEO) += teo.o
+obj-$(CONFIG_CPU_IDLE_GOV_HALTPOLL) += haltpoll.o
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * haltpoll.c - haltpoll idle governor
+ *
+ * Copyright 2019 Red Hat, Inc. and/or its affiliates.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ *
+ * Authors: Marcelo Tosatti <mtosatti@redhat.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/cpuidle.h>
+#include <linux/time.h>
+#include <linux/ktime.h>
+#include <linux/hrtimer.h>
+#include <linux/tick.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/kvm_para.h>
+
+static unsigned int guest_halt_poll_ns __read_mostly = 200000;
+module_param(guest_halt_poll_ns, uint, 0644);
+
+/* division factor to shrink halt_poll_ns */
+static unsigned int guest_halt_poll_shrink __read_mostly = 2;
+module_param(guest_halt_poll_shrink, uint, 0644);
+
+/* multiplication factor to grow per-cpu poll_limit_ns */
+static unsigned int guest_halt_poll_grow __read_mostly = 2;
+module_param(guest_halt_poll_grow, uint, 0644);
+
+/* value in us to start growing per-cpu halt_poll_ns */
+static unsigned int guest_halt_poll_grow_start __read_mostly = 50000;
+module_param(guest_halt_poll_grow_start, uint, 0644);
+
+/* allow shrinking guest halt poll */
+static bool guest_halt_poll_allow_shrink __read_mostly = true;
+module_param(guest_halt_poll_allow_shrink, bool, 0644);
+
+/**
+ * haltpoll_select - selects the next idle state to enter
+ * @drv: cpuidle driver containing state data
+ * @dev: the CPU
+ * @stop_tick: indication on whether or not to stop the tick
+ */
+static int haltpoll_select(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev,
+ bool *stop_tick)
+{
+ int latency_req = cpuidle_governor_latency_req(dev->cpu);
+
+ if (!drv->state_count || latency_req == 0) {
+ *stop_tick = false;
+ return 0;
+ }
+
+ if (dev->poll_limit_ns == 0)
+ return 1;
+
+ /* Last state was poll? */
+ if (dev->last_state_idx == 0) {
+ /* Halt if no event occurred on poll window */
+ if (dev->poll_time_limit == true)
+ return 1;
+
+ *stop_tick = false;
+ /* Otherwise, poll again */
+ return 0;
+ }
+
+ *stop_tick = false;
+ /* Last state was halt: poll */
+ return 0;
+}
+
+static void adjust_poll_limit(struct cpuidle_device *dev, unsigned int block_us)
+{
+ unsigned int val;
+ u64 block_ns = block_us*NSEC_PER_USEC;
+
+ /* Grow cpu_halt_poll_us if
+ * cpu_halt_poll_us < block_ns < guest_halt_poll_us
+ */
+ if (block_ns > dev->poll_limit_ns && block_ns <= guest_halt_poll_ns) {
+ val = dev->poll_limit_ns * guest_halt_poll_grow;
+
+ if (val < guest_halt_poll_grow_start)
+ val = guest_halt_poll_grow_start;
+ if (val > guest_halt_poll_ns)
+ val = guest_halt_poll_ns;
+
+ dev->poll_limit_ns = val;
+ } else if (block_ns > guest_halt_poll_ns &&
+ guest_halt_poll_allow_shrink) {
+ unsigned int shrink = guest_halt_poll_shrink;
+
+ val = dev->poll_limit_ns;
+ if (shrink == 0)
+ val = 0;
+ else
+ val /= shrink;
+ dev->poll_limit_ns = val;
+ }
+}
+
+/**
+ * haltpoll_reflect - update variables and update poll time
+ * @dev: the CPU
+ * @index: the index of actual entered state
+ */
+static void haltpoll_reflect(struct cpuidle_device *dev, int index)
+{
+ dev->last_state_idx = index;
+
+ if (index != 0)
+ adjust_poll_limit(dev, dev->last_residency);
+}
+
+/**
+ * haltpoll_enable_device - scans a CPU's states and does setup
+ * @drv: cpuidle driver
+ * @dev: the CPU
+ */
+static int haltpoll_enable_device(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev)
+{
+ dev->poll_limit_ns = 0;
+
+ return 0;
+}
+
+static struct cpuidle_governor haltpoll_governor = {
+ .name = "haltpoll",
+ .rating = 9,
+ .enable = haltpoll_enable_device,
+ .select = haltpoll_select,
+ .reflect = haltpoll_reflect,
+};
+
+static int __init init_haltpoll(void)
+{
+ if (kvm_para_available())
+ return cpuidle_register_governor(&haltpoll_governor);
+
+ return 0;
+}
+
+postcore_initcall(init_haltpoll);
struct ladder_device {
struct ladder_device_state states[CPUIDLE_STATE_MAX];
- int last_state_idx;
};
static DEFINE_PER_CPU(struct ladder_device, ladder_devices);
* @old_idx: the current state index
* @new_idx: the new target state index
*/
-static inline void ladder_do_selection(struct ladder_device *ldev,
+static inline void ladder_do_selection(struct cpuidle_device *dev,
+ struct ladder_device *ldev,
int old_idx, int new_idx)
{
ldev->states[old_idx].stats.promotion_count = 0;
ldev->states[old_idx].stats.demotion_count = 0;
- ldev->last_state_idx = new_idx;
+ dev->last_state_idx = new_idx;
}
/**
{
struct ladder_device *ldev = this_cpu_ptr(&ladder_devices);
struct ladder_device_state *last_state;
- int last_residency, last_idx = ldev->last_state_idx;
+ int last_residency, last_idx = dev->last_state_idx;
int first_idx = drv->states[0].flags & CPUIDLE_FLAG_POLLING ? 1 : 0;
int latency_req = cpuidle_governor_latency_req(dev->cpu);
/* Special case when user has set very strict latency requirement */
if (unlikely(latency_req == 0)) {
- ladder_do_selection(ldev, last_idx, 0);
+ ladder_do_selection(dev, ldev, last_idx, 0);
return 0;
}
last_state->stats.promotion_count++;
last_state->stats.demotion_count = 0;
if (last_state->stats.promotion_count >= last_state->threshold.promotion_count) {
- ladder_do_selection(ldev, last_idx, last_idx + 1);
+ ladder_do_selection(dev, ldev, last_idx, last_idx + 1);
return last_idx + 1;
}
}
if (drv->states[i].exit_latency <= latency_req)
break;
}
- ladder_do_selection(ldev, last_idx, i);
+ ladder_do_selection(dev, ldev, last_idx, i);
return i;
}
last_state->stats.demotion_count++;
last_state->stats.promotion_count = 0;
if (last_state->stats.demotion_count >= last_state->threshold.demotion_count) {
- ladder_do_selection(ldev, last_idx, last_idx - 1);
+ ladder_do_selection(dev, ldev, last_idx, last_idx - 1);
return last_idx - 1;
}
}
struct ladder_device_state *lstate;
struct cpuidle_state *state;
- ldev->last_state_idx = first_idx;
+ dev->last_state_idx = first_idx;
for (i = first_idx; i < drv->state_count; i++) {
state = &drv->states[i];
*/
static void ladder_reflect(struct cpuidle_device *dev, int index)
{
- struct ladder_device *ldev = this_cpu_ptr(&ladder_devices);
if (index > 0)
- ldev->last_state_idx = index;
+ dev->last_state_idx = index;
}
static struct cpuidle_governor ladder_governor = {
*/
struct menu_device {
- int last_state_idx;
int needs_update;
int tick_wakeup;
!drv->states[0].disabled && !dev->states_usage[0].disable)) {
/*
* In this case state[0] will be used no matter what, so return
- * it right away and keep the tick running.
+ * it right away and keep the tick running if state[0] is a
+ * polling one.
*/
- *stop_tick = false;
+ *stop_tick = !(drv->states[0].flags & CPUIDLE_FLAG_POLLING);
return 0;
}
return idx;
}
- if (s->exit_latency > latency_req) {
- /*
- * If we break out of the loop for latency reasons, use
- * the target residency of the selected state as the
- * expected idle duration so that the tick is retained
- * as long as that target residency is low enough.
- */
- predicted_us = drv->states[idx].target_residency;
+ if (s->exit_latency > latency_req)
break;
- }
+
idx = i;
}
{
struct menu_device *data = this_cpu_ptr(&menu_devices);
- data->last_state_idx = index;
+ dev->last_state_idx = index;
data->needs_update = 1;
data->tick_wakeup = tick_nohz_idle_got_tick();
}
static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
{
struct menu_device *data = this_cpu_ptr(&menu_devices);
- int last_idx = data->last_state_idx;
+ int last_idx = dev->last_state_idx;
struct cpuidle_state *target = &drv->states[last_idx];
unsigned int measured_us;
unsigned int new_factor;
* @time_span_ns: Time between idle state selection and post-wakeup update.
* @sleep_length_ns: Time till the closest timer event (at the selection time).
* @states: Idle states data corresponding to this CPU.
- * @last_state: Idle state entered by the CPU last time.
* @interval_idx: Index of the most recent saved idle interval.
* @intervals: Saved idle duration values.
*/
u64 time_span_ns;
u64 sleep_length_ns;
struct teo_idle_state states[CPUIDLE_STATE_MAX];
- int last_state;
int interval_idx;
unsigned int intervals[INTERVALS];
};
if (cpu_data->time_span_ns >= cpu_data->sleep_length_ns) {
/*
- * One of the safety nets has triggered or this was a timer
- * wakeup (or equivalent).
+ * One of the safety nets has triggered or the wakeup was close
+ * enough to the closest timer event expected at the idle state
+ * selection time to be discarded.
*/
- measured_us = sleep_length_us;
+ measured_us = UINT_MAX;
} else {
- unsigned int lat = drv->states[cpu_data->last_state].exit_latency;
+ unsigned int lat;
+
+ lat = drv->states[dev->last_state_idx].exit_latency;
measured_us = ktime_to_us(cpu_data->time_span_ns);
/*
cpu_data->states[idx_timer].hits = hits;
}
- /*
- * If the total time span between idle state selection and the "reflect"
- * callback is greater than or equal to the sleep length determined at
- * the idle state selection time, the wakeup is likely to be due to a
- * timer event.
- */
- if (cpu_data->time_span_ns >= cpu_data->sleep_length_ns)
- measured_us = UINT_MAX;
-
/*
* Save idle duration values corresponding to non-timer wakeups for
* pattern detection.
struct teo_cpu *cpu_data = per_cpu_ptr(&teo_cpus, dev->cpu);
int latency_req = cpuidle_governor_latency_req(dev->cpu);
unsigned int duration_us, count;
- int max_early_idx, idx, i;
+ int max_early_idx, constraint_idx, idx, i;
ktime_t delta_tick;
- if (cpu_data->last_state >= 0) {
+ if (dev->last_state_idx >= 0) {
teo_update(drv, dev);
- cpu_data->last_state = -1;
+ dev->last_state_idx = -1;
}
cpu_data->time_span_ns = local_clock();
count = 0;
max_early_idx = -1;
+ constraint_idx = drv->state_count;
idx = -1;
for (i = 0; i < drv->state_count; i++) {
if (s->target_residency > duration_us)
break;
- if (s->exit_latency > latency_req) {
- /*
- * If we break out of the loop for latency reasons, use
- * the target residency of the selected state as the
- * expected idle duration to avoid stopping the tick
- * as long as that target residency is low enough.
- */
- duration_us = drv->states[idx].target_residency;
- goto refine;
- }
+ if (s->exit_latency > latency_req && constraint_idx > i)
+ constraint_idx = i;
idx = i;
duration_us = drv->states[idx].target_residency;
}
-refine:
+ /*
+ * If there is a latency constraint, it may be necessary to use a
+ * shallower idle state than the one selected so far.
+ */
+ if (constraint_idx < idx)
+ idx = constraint_idx;
+
if (idx < 0) {
idx = 0; /* No states enabled. Must use 0. */
} else if (idx > 0) {
/*
* Count and sum the most recent idle duration values less than
- * the target residency of the state selected so far, find the
- * max.
+ * the current expected idle duration value.
*/
for (i = 0; i < INTERVALS; i++) {
unsigned int val = cpu_data->intervals[i];
- if (val >= drv->states[idx].target_residency)
+ if (val >= duration_us)
continue;
count++;
* would be too shallow.
*/
if (!(tick_nohz_tick_stopped() && avg_us < TICK_USEC)) {
- idx = teo_find_shallower_state(drv, dev, idx, avg_us);
duration_us = avg_us;
+ if (drv->states[idx].target_residency > avg_us)
+ idx = teo_find_shallower_state(drv, dev,
+ idx, avg_us);
}
}
}
{
struct teo_cpu *cpu_data = per_cpu_ptr(&teo_cpus, dev->cpu);
- cpu_data->last_state = state;
+ dev->last_state_idx = state;
/*
* If the wakeup was not "natural", but triggered by one of the safety
* nets, assume that the CPU might have been idle for the entire sleep
local_irq_enable();
if (!current_set_polling_and_test()) {
unsigned int loop_count = 0;
- u64 limit = TICK_NSEC;
- int i;
+ u64 limit;
- for (i = 1; i < drv->state_count; i++) {
- if (drv->states[i].disabled || dev->states_usage[i].disable)
- continue;
-
- limit = (u64)drv->states[i].target_residency * NSEC_PER_USEC;
- break;
- }
+ limit = cpuidle_poll_time(drv, dev);
while (!need_resched()) {
cpu_relax();
struct cpuidle_state_usage *state_usage;
struct completion kobj_unregister;
struct kobject kobj;
+ struct cpuidle_device *device;
};
#ifdef CONFIG_SUSPEND
#define kobj_to_state_obj(k) container_of(k, struct cpuidle_state_kobj, kobj)
#define kobj_to_state(k) (kobj_to_state_obj(k)->state)
#define kobj_to_state_usage(k) (kobj_to_state_obj(k)->state_usage)
+#define kobj_to_device(k) (kobj_to_state_obj(k)->device)
#define attr_to_stateattr(a) container_of(a, struct cpuidle_state_attr, attr)
static ssize_t cpuidle_state_show(struct kobject *kobj, struct attribute *attr,
struct cpuidle_state *state = kobj_to_state(kobj);
struct cpuidle_state_usage *state_usage = kobj_to_state_usage(kobj);
struct cpuidle_state_attr *cattr = attr_to_stateattr(attr);
+ struct cpuidle_device *dev = kobj_to_device(kobj);
if (cattr->store)
ret = cattr->store(state, state_usage, buf, size);
+ /* reset poll time cache */
+ dev->poll_limit_ns = 0;
+
return ret;
}
}
kobj->state = &drv->states[i];
kobj->state_usage = &device->states_usage[i];
+ kobj->device = device;
init_completion(&kobj->kobj_unregister);
ret = kobject_init_and_add(&kobj->kobj, &ktype_state_cpuidle,
/**
* struct idle_inject_device - idle injection data
* @timer: idle injection period timer
- * @idle_duration_ms: duration of CPU idle time to inject
- * @run_duration_ms: duration of CPU run time to allow
+ * @idle_duration_us: duration of CPU idle time to inject
+ * @run_duration_us: duration of CPU run time to allow
* @cpumask: mask of CPUs affected by idle injection
*/
struct idle_inject_device {
struct hrtimer timer;
- unsigned int idle_duration_ms;
- unsigned int run_duration_ms;
+ unsigned int idle_duration_us;
+ unsigned int run_duration_us;
unsigned long int cpumask[0];
};
*/
static enum hrtimer_restart idle_inject_timer_fn(struct hrtimer *timer)
{
- unsigned int duration_ms;
+ unsigned int duration_us;
struct idle_inject_device *ii_dev =
container_of(timer, struct idle_inject_device, timer);
- duration_ms = READ_ONCE(ii_dev->run_duration_ms);
- duration_ms += READ_ONCE(ii_dev->idle_duration_ms);
+ duration_us = READ_ONCE(ii_dev->run_duration_us);
+ duration_us += READ_ONCE(ii_dev->idle_duration_us);
idle_inject_wakeup(ii_dev);
- hrtimer_forward_now(timer, ms_to_ktime(duration_ms));
+ hrtimer_forward_now(timer, ns_to_ktime(duration_us * NSEC_PER_USEC));
return HRTIMER_RESTART;
}
*/
iit->should_run = 0;
- play_idle(READ_ONCE(ii_dev->idle_duration_ms));
+ play_idle(READ_ONCE(ii_dev->idle_duration_us));
}
/**
* idle_inject_set_duration - idle and run duration update helper
- * @run_duration_ms: CPU run time to allow in milliseconds
- * @idle_duration_ms: CPU idle time to inject in milliseconds
+ * @run_duration_us: CPU run time to allow in microseconds
+ * @idle_duration_us: CPU idle time to inject in microseconds
*/
void idle_inject_set_duration(struct idle_inject_device *ii_dev,
- unsigned int run_duration_ms,
- unsigned int idle_duration_ms)
+ unsigned int run_duration_us,
+ unsigned int idle_duration_us)
{
- if (run_duration_ms && idle_duration_ms) {
- WRITE_ONCE(ii_dev->run_duration_ms, run_duration_ms);
- WRITE_ONCE(ii_dev->idle_duration_ms, idle_duration_ms);
+ if (run_duration_us && idle_duration_us) {
+ WRITE_ONCE(ii_dev->run_duration_us, run_duration_us);
+ WRITE_ONCE(ii_dev->idle_duration_us, idle_duration_us);
}
}
/**
* idle_inject_get_duration - idle and run duration retrieval helper
- * @run_duration_ms: memory location to store the current CPU run time
- * @idle_duration_ms: memory location to store the current CPU idle time
+ * @run_duration_us: memory location to store the current CPU run time
+ * @idle_duration_us: memory location to store the current CPU idle time
*/
void idle_inject_get_duration(struct idle_inject_device *ii_dev,
- unsigned int *run_duration_ms,
- unsigned int *idle_duration_ms)
+ unsigned int *run_duration_us,
+ unsigned int *idle_duration_us)
{
- *run_duration_ms = READ_ONCE(ii_dev->run_duration_ms);
- *idle_duration_ms = READ_ONCE(ii_dev->idle_duration_ms);
+ *run_duration_us = READ_ONCE(ii_dev->run_duration_us);
+ *idle_duration_us = READ_ONCE(ii_dev->idle_duration_us);
}
/**
*/
int idle_inject_start(struct idle_inject_device *ii_dev)
{
- unsigned int idle_duration_ms = READ_ONCE(ii_dev->idle_duration_ms);
- unsigned int run_duration_ms = READ_ONCE(ii_dev->run_duration_ms);
+ unsigned int idle_duration_us = READ_ONCE(ii_dev->idle_duration_us);
+ unsigned int run_duration_us = READ_ONCE(ii_dev->run_duration_us);
- if (!idle_duration_ms || !run_duration_ms)
+ if (!idle_duration_us || !run_duration_us)
return -EINVAL;
pr_debug("Starting injecting idle cycles on CPUs '%*pbl'\n",
idle_inject_wakeup(ii_dev);
hrtimer_start(&ii_dev->timer,
- ms_to_ktime(idle_duration_ms + run_duration_ms),
+ ns_to_ktime((idle_duration_us + run_duration_us) *
+ NSEC_PER_USEC),
HRTIMER_MODE_REL);
return 0;
if (should_skip)
goto balance;
- play_idle(jiffies_to_msecs(w_data->duration_jiffies));
+ play_idle(jiffies_to_usecs(w_data->duration_jiffies));
balance:
if (clamping && w_data->clamping && cpu_online(w_data->cpu))
int cpu_report_state(int cpu);
int cpu_check_up_prepare(int cpu);
void cpu_set_state_online(int cpu);
-void play_idle(unsigned long duration_ms);
+void play_idle(unsigned long duration_us);
#ifdef CONFIG_HOTPLUG_CPU
bool cpu_wait_death(unsigned int cpu, int seconds);
unsigned int cpu;
ktime_t next_hrtimer;
+ int last_state_idx;
int last_residency;
+ u64 poll_limit_ns;
struct cpuidle_state_usage states_usage[CPUIDLE_STATE_MAX];
struct cpuidle_state_kobj *kobjs[CPUIDLE_STATE_MAX];
struct cpuidle_driver_kobj *kobj_driver;
/* the driver handles the cpus in cpumask */
struct cpumask *cpumask;
+
+ /* preferred governor to switch at register time */
+ const char *governor;
};
#ifdef CONFIG_CPU_IDLE
extern int cpuidle_enter(struct cpuidle_driver *drv,
struct cpuidle_device *dev, int index);
extern void cpuidle_reflect(struct cpuidle_device *dev, int index);
+extern u64 cpuidle_poll_time(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev);
extern int cpuidle_register_driver(struct cpuidle_driver *drv);
extern struct cpuidle_driver *cpuidle_get_driver(void);
struct cpuidle_device *dev, int index)
{return -ENODEV; }
static inline void cpuidle_reflect(struct cpuidle_device *dev, int index) { }
+static inline u64 cpuidle_poll_time(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev)
+{return 0; }
static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
{return -ENODEV; }
static inline struct cpuidle_driver *cpuidle_get_driver(void) {return NULL; }
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _CPUIDLE_HALTPOLL_H
+#define _CPUIDLE_HALTPOLL_H
+
+#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
+#include <asm/cpuidle_haltpoll.h>
+#else
+static inline void arch_haltpoll_enable(unsigned int cpu)
+{
+}
+
+static inline void arch_haltpoll_disable(unsigned int cpu)
+{
+}
+#endif
+#endif
void idle_inject_stop(struct idle_inject_device *ii_dev);
void idle_inject_set_duration(struct idle_inject_device *ii_dev,
- unsigned int run_duration_ms,
- unsigned int idle_duration_ms);
+ unsigned int run_duration_us,
+ unsigned int idle_duration_us);
void idle_inject_get_duration(struct idle_inject_device *ii_dev,
- unsigned int *run_duration_ms,
- unsigned int *idle_duration_ms);
+ unsigned int *run_duration_us,
+ unsigned int *idle_duration_us);
#endif /* __IDLE_INJECT_H__ */
return HRTIMER_NORESTART;
}
-void play_idle(unsigned long duration_ms)
+void play_idle(unsigned long duration_us)
{
struct idle_timer it;
WARN_ON_ONCE(current->nr_cpus_allowed != 1);
WARN_ON_ONCE(!(current->flags & PF_KTHREAD));
WARN_ON_ONCE(!(current->flags & PF_NO_SETAFFINITY));
- WARN_ON_ONCE(!duration_ms);
+ WARN_ON_ONCE(!duration_us);
rcu_sleep_check();
preempt_disable();
it.done = 0;
hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
it.timer.function = idle_inject_timer_fn;
- hrtimer_start(&it.timer, ms_to_ktime(duration_ms), HRTIMER_MODE_REL_PINNED);
+ hrtimer_start(&it.timer, ns_to_ktime(duration_us * NSEC_PER_USEC),
+ HRTIMER_MODE_REL_PINNED);
while (!READ_ONCE(it.done))
do_idle();
projects / linux-2.6-block.git / commitdiff