[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>

1 files changed, 62 insertions, 51 deletions

diff --git a/arch/ppc64/kernel/pSeries_setup.c b/arch/ppc64/kernel/pSeries_setup.c
index 3f3be8ae9351..5bec956e44a0 100644
--- 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();
         }