diff options
Diffstat (limited to 'arch/ppc64/kernel/pSeries_setup.c')
| -rw-r--r-- | arch/ppc64/kernel/pSeries_setup.c | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/arch/ppc64/kernel/pSeries_setup.c b/arch/ppc64/kernel/pSeries_setup.c index 44d9af72d225..5bec956e44a0 100644 --- a/arch/ppc64/kernel/pSeries_setup.c +++ b/arch/ppc64/kernel/pSeries_setup.c @@ -19,6 +19,7 @@ #undef DEBUG #include <linux/config.h> +#include <linux/cpu.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/kernel.h> @@ -82,6 +83,9 @@ int fwnmi_active; /* TRUE if an FWNMI handler is present */ extern void pSeries_system_reset_exception(struct pt_regs *regs); extern int pSeries_machine_check_exception(struct pt_regs *regs); +static int pseries_shared_idle(void); +static int pseries_dedicated_idle(void); + static volatile void __iomem * chrp_int_ack_special; struct mpic *pSeries_mpic; @@ -229,6 +233,20 @@ static void __init pSeries_setup_arch(void) if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) vpa_init(boot_cpuid); + + /* Choose an idle loop */ + if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) { + if (get_paca()->lppaca.shared_proc) { + printk(KERN_INFO "Using shared processor idle loop\n"); + ppc_md.idle_loop = pseries_shared_idle; + } else { + printk(KERN_INFO "Using dedicated idle loop\n"); + ppc_md.idle_loop = pseries_dedicated_idle; + } + } else { + printk(KERN_INFO "Using default idle loop\n"); + ppc_md.idle_loop = default_idle; + } } static int __init pSeries_init_panel(void) @@ -418,6 +436,144 @@ static int __init pSeries_probe(int platform) return 1; } +DECLARE_PER_CPU(unsigned long, smt_snooze_delay); + +static inline void dedicated_idle_sleep(unsigned int cpu) +{ + struct paca_struct *ppaca = &paca[cpu ^ 1]; + + /* Only sleep if the other thread is not idle */ + if (!(ppaca->lppaca.idle)) { + local_irq_disable(); + + /* + * We are about to sleep the thread and so wont be polling any + * more. + */ + clear_thread_flag(TIF_POLLING_NRFLAG); + + /* + * SMT dynamic mode. Cede will result in this thread going + * dormant, if the partner thread is still doing work. Thread + * wakes up if partner goes idle, an interrupt is presented, or + * a prod occurs. Returning from the cede enables external + * interrupts. + */ + if (!need_resched()) + cede_processor(); + else + local_irq_enable(); + } else { + /* + * Give the HV an opportunity at the processor, since we are + * not doing any work. + */ + poll_pending(); + } +} + +static int pseries_dedicated_idle(void) +{ + long oldval; + struct paca_struct *lpaca = get_paca(); + unsigned int cpu = smp_processor_id(); + unsigned long start_snooze; + unsigned long *smt_snooze_delay = &__get_cpu_var(smt_snooze_delay); + + while (1) { + /* + * Indicate to the HV that we are idle. Now would be + * a good time to find other work to dispatch. + */ + lpaca->lppaca.idle = 1; + + oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED); + if (!oldval) { + set_thread_flag(TIF_POLLING_NRFLAG); + + start_snooze = __get_tb() + + *smt_snooze_delay * tb_ticks_per_usec; + + while (!need_resched() && !cpu_is_offline(cpu)) { + ppc64_runlatch_off(); + + /* + * Go into low thread priority and possibly + * low power mode. + */ + HMT_low(); + HMT_very_low(); + + if (*smt_snooze_delay != 0 && + __get_tb() > start_snooze) { + HMT_medium(); + dedicated_idle_sleep(cpu); + } + + } + + HMT_medium(); + clear_thread_flag(TIF_POLLING_NRFLAG); + } else { + set_need_resched(); + } + + lpaca->lppaca.idle = 0; + ppc64_runlatch_on(); + + schedule(); + + if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING) + cpu_die(); + } +} + +static int pseries_shared_idle(void) +{ + struct paca_struct *lpaca = get_paca(); + unsigned int cpu = smp_processor_id(); + + while (1) { + /* + * Indicate to the HV that we are idle. Now would be + * a good time to find other work to dispatch. + */ + lpaca->lppaca.idle = 1; + + while (!need_resched() && !cpu_is_offline(cpu)) { + local_irq_disable(); + ppc64_runlatch_off(); + + /* + * 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 need_resched() again with interrupts disabled + * to avoid a race. + */ + if (!need_resched()) + cede_processor(); + else + local_irq_enable(); + + HMT_medium(); + } + + lpaca->lppaca.idle = 0; + ppc64_runlatch_on(); + + schedule(); + + if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING) + cpu_die(); + } + + return 0; +} + struct machdep_calls __initdata pSeries_md = { .probe = pSeries_probe, .setup_arch = pSeries_setup_arch, |
