From 8ea959a17fe6e27f7954dddad5b17b0e33f0d7ee Mon Sep 17 00:00:00 2001 From: Deepthi Dharwar Date: Wed, 3 Oct 2012 18:42:18 +0000 Subject: cpuidle/powerpc: Fix smt_snooze_delay functionality. smt_snooze_delay was designed to delay idle loop's nap entry in the native idle code before it got ported over to use as part of the cpuidle framework. A -ve value assigned to smt_snooze_delay should result in busy looping, in other words disabling the entry to nap state. - https://lists.ozlabs.org/pipermail/linuxppc-dev/2010-May/082450.html This particular functionality can be achieved currently by echo 1 > /sys/devices/system/cpu/cpu*/state1/disable but it is broken when one assigns -ve value to the smt_snooze_delay variable either via sysfs entry or ppc64_cpu util. This patch aims to fix this, by disabling nap state when smt_snooze_delay variable is set to -ve value. Signed-off-by: Deepthi Dharwar Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/processor.h | 4 ++-- arch/powerpc/kernel/sysfs.c | 2 +- arch/powerpc/platforms/pseries/processor_idle.c | 24 +++++++++++++++++------- 3 files changed, 20 insertions(+), 10 deletions(-) diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index 8734b385527..87502046c0d 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -388,9 +388,9 @@ extern int powersave_nap; /* set if nap mode can be used in idle loop */ extern void power7_nap(void); #ifdef CONFIG_PSERIES_IDLE -extern void update_smt_snooze_delay(int snooze); +extern void update_smt_snooze_delay(int cpu, int residency); #else -static inline void update_smt_snooze_delay(int snooze) {} +static inline void update_smt_snooze_delay(int cpu, int residency) {} #endif extern void flush_instruction_cache(void); diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c index 8302af64921..cf357a059dd 100644 --- a/arch/powerpc/kernel/sysfs.c +++ b/arch/powerpc/kernel/sysfs.c @@ -50,7 +50,7 @@ static ssize_t store_smt_snooze_delay(struct device *dev, return -EINVAL; per_cpu(smt_snooze_delay, cpu->dev.id) = snooze; - update_smt_snooze_delay(snooze); + update_smt_snooze_delay(cpu->dev.id, snooze); return count; } diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c index 02e425aa2af..a32d56d1f85 100644 --- a/arch/powerpc/platforms/pseries/processor_idle.c +++ b/arch/powerpc/platforms/pseries/processor_idle.c @@ -33,13 +33,6 @@ static int max_idle_state = MAX_IDLE_STATE_COUNT - 1; static struct cpuidle_device __percpu *pseries_cpuidle_devices; static struct cpuidle_state *cpuidle_state_table; -void update_smt_snooze_delay(int snooze) -{ - struct cpuidle_driver *drv = cpuidle_get_driver(); - if (drv) - drv->states[0].target_residency = snooze; -} - static inline void idle_loop_prolog(unsigned long *in_purr, ktime_t *kt_before) { @@ -190,6 +183,23 @@ static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = { .enter = &shared_cede_loop }, }; +void update_smt_snooze_delay(int cpu, int residency) +{ + struct cpuidle_driver *drv = cpuidle_get_driver(); + struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); + + if (cpuidle_state_table != dedicated_states) + return; + + if (residency < 0) { + /* Disable the Nap state on that cpu */ + if (dev) + dev->states_usage[1].disable = 1; + } else + if (drv) + drv->states[0].target_residency = residency; +} + static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n, unsigned long action, void *hcpu) { -- cgit v1.2.3-70-g09d2