![Deepthi Dharwar](/assets/img/avatar_default.png)
smt-snooze-delay was designed to disable NAP state or delay the entry to the NAP state prior to adoption of cpuidle framework. This is per-cpu variable. With the coming of CPUIDLE framework, states can be disabled on per-cpu basis using the cpuidle/enable sysfs entry. Also, with the coming of cpuidle driver each state's target residency is per-driver unlike earlier which was per-device. Therefore, the per-cpu sysfs smt-snooze-delay which decides the target residency of the idle state on a particular cpu causes more confusion to the user as we cannot have different smt-snooze-delay (target residency) values for each cpu. In the current code, smt-snooze-delay functionality is completely broken. It makes sense to remove smt-snooze-delay from idle driver with the coming of cpuidle framework. However, sysfs files are retained as ppc64_util currently utilises it. Once we fix ppc64_util, propose to clean up the kernel code. Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
268 lines
5.6 KiB
C
268 lines
5.6 KiB
C
/*
|
|
* cpuidle-pseries - idle state cpuidle driver.
|
|
* Adapted from drivers/idle/intel_idle.c and
|
|
* drivers/acpi/processor_idle.c
|
|
*
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/init.h>
|
|
#include <linux/moduleparam.h>
|
|
#include <linux/cpuidle.h>
|
|
#include <linux/cpu.h>
|
|
#include <linux/notifier.h>
|
|
|
|
#include <asm/paca.h>
|
|
#include <asm/reg.h>
|
|
#include <asm/machdep.h>
|
|
#include <asm/firmware.h>
|
|
#include <asm/plpar_wrappers.h>
|
|
|
|
struct cpuidle_driver pseries_idle_driver = {
|
|
.name = "pseries_idle",
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
static int max_idle_state;
|
|
static struct cpuidle_state *cpuidle_state_table;
|
|
|
|
static inline void idle_loop_prolog(unsigned long *in_purr)
|
|
{
|
|
*in_purr = mfspr(SPRN_PURR);
|
|
/*
|
|
* Indicate to the HV that we are idle. Now would be
|
|
* a good time to find other work to dispatch.
|
|
*/
|
|
get_lppaca()->idle = 1;
|
|
}
|
|
|
|
static inline void idle_loop_epilog(unsigned long in_purr)
|
|
{
|
|
u64 wait_cycles;
|
|
|
|
wait_cycles = be64_to_cpu(get_lppaca()->wait_state_cycles);
|
|
wait_cycles += mfspr(SPRN_PURR) - in_purr;
|
|
get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles);
|
|
get_lppaca()->idle = 0;
|
|
}
|
|
|
|
static int snooze_loop(struct cpuidle_device *dev,
|
|
struct cpuidle_driver *drv,
|
|
int index)
|
|
{
|
|
unsigned long in_purr;
|
|
|
|
idle_loop_prolog(&in_purr);
|
|
local_irq_enable();
|
|
set_thread_flag(TIF_POLLING_NRFLAG);
|
|
|
|
while (!need_resched()) {
|
|
HMT_low();
|
|
HMT_very_low();
|
|
}
|
|
|
|
HMT_medium();
|
|
clear_thread_flag(TIF_POLLING_NRFLAG);
|
|
smp_mb();
|
|
|
|
idle_loop_epilog(in_purr);
|
|
|
|
return index;
|
|
}
|
|
|
|
static void check_and_cede_processor(void)
|
|
{
|
|
/*
|
|
* Ensure our interrupt state is properly tracked,
|
|
* also checks if no interrupt has occurred while we
|
|
* were soft-disabled
|
|
*/
|
|
if (prep_irq_for_idle()) {
|
|
cede_processor();
|
|
#ifdef CONFIG_TRACE_IRQFLAGS
|
|
/* Ensure that H_CEDE returns with IRQs on */
|
|
if (WARN_ON(!(mfmsr() & MSR_EE)))
|
|
__hard_irq_enable();
|
|
#endif
|
|
}
|
|
}
|
|
|
|
static int dedicated_cede_loop(struct cpuidle_device *dev,
|
|
struct cpuidle_driver *drv,
|
|
int index)
|
|
{
|
|
unsigned long in_purr;
|
|
|
|
idle_loop_prolog(&in_purr);
|
|
get_lppaca()->donate_dedicated_cpu = 1;
|
|
|
|
HMT_medium();
|
|
check_and_cede_processor();
|
|
|
|
get_lppaca()->donate_dedicated_cpu = 0;
|
|
|
|
idle_loop_epilog(in_purr);
|
|
|
|
return index;
|
|
}
|
|
|
|
static int shared_cede_loop(struct cpuidle_device *dev,
|
|
struct cpuidle_driver *drv,
|
|
int index)
|
|
{
|
|
unsigned long in_purr;
|
|
|
|
idle_loop_prolog(&in_purr);
|
|
|
|
/*
|
|
* Yield the processor to the hypervisor. We return if
|
|
* an external interrupt occurs (which are driven prior
|
|
* to returning here) or if a prod occurs from another
|
|
* processor. When returning here, external interrupts
|
|
* are enabled.
|
|
*/
|
|
check_and_cede_processor();
|
|
|
|
idle_loop_epilog(in_purr);
|
|
|
|
return index;
|
|
}
|
|
|
|
/*
|
|
* States for dedicated partition case.
|
|
*/
|
|
static struct cpuidle_state dedicated_states[] = {
|
|
{ /* Snooze */
|
|
.name = "snooze",
|
|
.desc = "snooze",
|
|
.flags = CPUIDLE_FLAG_TIME_VALID,
|
|
.exit_latency = 0,
|
|
.target_residency = 0,
|
|
.enter = &snooze_loop },
|
|
{ /* CEDE */
|
|
.name = "CEDE",
|
|
.desc = "CEDE",
|
|
.flags = CPUIDLE_FLAG_TIME_VALID,
|
|
.exit_latency = 10,
|
|
.target_residency = 100,
|
|
.enter = &dedicated_cede_loop },
|
|
};
|
|
|
|
/*
|
|
* States for shared partition case.
|
|
*/
|
|
static struct cpuidle_state shared_states[] = {
|
|
{ /* Shared Cede */
|
|
.name = "Shared Cede",
|
|
.desc = "Shared Cede",
|
|
.flags = CPUIDLE_FLAG_TIME_VALID,
|
|
.exit_latency = 0,
|
|
.target_residency = 0,
|
|
.enter = &shared_cede_loop },
|
|
};
|
|
|
|
static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
int hotcpu = (unsigned long)hcpu;
|
|
struct cpuidle_device *dev =
|
|
per_cpu(cpuidle_devices, hotcpu);
|
|
|
|
if (dev && cpuidle_get_driver()) {
|
|
switch (action) {
|
|
case CPU_ONLINE:
|
|
case CPU_ONLINE_FROZEN:
|
|
cpuidle_pause_and_lock();
|
|
cpuidle_enable_device(dev);
|
|
cpuidle_resume_and_unlock();
|
|
break;
|
|
|
|
case CPU_DEAD:
|
|
case CPU_DEAD_FROZEN:
|
|
cpuidle_pause_and_lock();
|
|
cpuidle_disable_device(dev);
|
|
cpuidle_resume_and_unlock();
|
|
break;
|
|
|
|
default:
|
|
return NOTIFY_DONE;
|
|
}
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static struct notifier_block setup_hotplug_notifier = {
|
|
.notifier_call = pseries_cpuidle_add_cpu_notifier,
|
|
};
|
|
|
|
/*
|
|
* pseries_cpuidle_driver_init()
|
|
*/
|
|
static int pseries_cpuidle_driver_init(void)
|
|
{
|
|
int idle_state;
|
|
struct cpuidle_driver *drv = &pseries_idle_driver;
|
|
|
|
drv->state_count = 0;
|
|
|
|
for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
|
|
/* Is the state not enabled? */
|
|
if (cpuidle_state_table[idle_state].enter == NULL)
|
|
continue;
|
|
|
|
drv->states[drv->state_count] = /* structure copy */
|
|
cpuidle_state_table[idle_state];
|
|
|
|
drv->state_count += 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* pseries_idle_probe()
|
|
* Choose state table for shared versus dedicated partition
|
|
*/
|
|
static int pseries_idle_probe(void)
|
|
{
|
|
|
|
if (cpuidle_disable != IDLE_NO_OVERRIDE)
|
|
return -ENODEV;
|
|
|
|
if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
|
|
if (lppaca_shared_proc(get_lppaca())) {
|
|
cpuidle_state_table = shared_states;
|
|
max_idle_state = ARRAY_SIZE(shared_states);
|
|
} else {
|
|
cpuidle_state_table = dedicated_states;
|
|
max_idle_state = ARRAY_SIZE(dedicated_states);
|
|
}
|
|
} else
|
|
return -ENODEV;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __init pseries_processor_idle_init(void)
|
|
{
|
|
int retval;
|
|
|
|
retval = pseries_idle_probe();
|
|
if (retval)
|
|
return retval;
|
|
|
|
pseries_cpuidle_driver_init();
|
|
retval = cpuidle_register(&pseries_idle_driver, NULL);
|
|
if (retval) {
|
|
printk(KERN_DEBUG "Registration of pseries driver failed.\n");
|
|
return retval;
|
|
}
|
|
|
|
register_cpu_notifier(&setup_hotplug_notifier);
|
|
printk(KERN_DEBUG "pseries_idle_driver registered\n");
|
|
return 0;
|
|
}
|
|
|
|
device_initcall(pseries_processor_idle_init);
|