[PATCH] ppc64: pSeries idle fixups

- separate out sleep logic in dedicated_idle, it was so far indented
  that it got squashed against the right side of the screen.
- add runlatch support, looping on runlatch disable.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/ppc64/kernel/pSeries_setup.c b/arch/ppc64/kernel/pSeries_setup.c
index 3f3be8ae935145d49a8776beffcf232c47f8cddb..5bec956e44a043775ffbd264807cebced14dfc77 100644 (file)
--- a/arch/ppc64/kernel/pSeries_setup.c
+++ b/arch/ppc64/kernel/pSeries_setup.c
@@ -83,8 +83,8 @@ 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 shared_idle(void);
-static int dedicated_idle(void);
+static int pseries_shared_idle(void);
+static int pseries_dedicated_idle(void);
 
 static volatile void __iomem * chrp_int_ack_special;
 struct mpic *pSeries_mpic;
@@ -238,10 +238,10 @@ static void __init pSeries_setup_arch(void)
        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 = shared_idle;
+                       ppc_md.idle_loop = pseries_shared_idle;
                } else {
                        printk(KERN_INFO "Using dedicated idle loop\n");
-                       ppc_md.idle_loop = dedicated_idle;
+                       ppc_md.idle_loop = pseries_dedicated_idle;
                }
        } else {
                printk(KERN_INFO "Using default idle loop\n");
@@ -438,15 +438,47 @@ static int __init pSeries_probe(int platform)
 
 DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
 
-int dedicated_idle(void)
+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(), *ppaca;
+       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);
-       unsigned int cpu = smp_processor_id();
-
-       ppaca = &paca[cpu ^ 1];
 
        while (1) {
                /*
@@ -458,9 +490,13 @@ int dedicated_idle(void)
                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.
@@ -468,60 +504,31 @@ int dedicated_idle(void)
                                HMT_low();
                                HMT_very_low();
 
-                               if (*smt_snooze_delay == 0 ||
-                                   __get_tb() < start_snooze)
-                                       continue;
-
-                               HMT_medium();
-
-                               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();
+                               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();
                }
 
-               HMT_medium();
                lpaca->lppaca.idle = 0;
+               ppc64_runlatch_on();
+
                schedule();
+
                if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
                        cpu_die();
        }
-       return 0;
 }
 
-static int shared_idle(void)
+static int pseries_shared_idle(void)
 {
        struct paca_struct *lpaca = get_paca();
        unsigned int cpu = smp_processor_id();
@@ -535,6 +542,7 @@ static int shared_idle(void)
 
                while (!need_resched() && !cpu_is_offline(cpu)) {
                        local_irq_disable();
+                       ppc64_runlatch_off();
 
                        /*
                         * Yield the processor to the hypervisor.  We return if
@@ -550,13 +558,16 @@ static int shared_idle(void)
                                cede_processor();
                        else
                                local_irq_enable();
+
+                       HMT_medium();
                }
 
-               HMT_medium();
                lpaca->lppaca.idle = 0;
+               ppc64_runlatch_on();
+
                schedule();
-               if (cpu_is_offline(smp_processor_id()) &&
-                   system_state == SYSTEM_RUNNING)
+
+               if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
                        cpu_die();
        }