2 files changed, 71 insertions, 120 deletions

diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 44d5c7fdcd97..213bf983242f 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -81,8 +81,8 @@ extern void find_udbg_vterm(void);
 
 int fwnmi_active;  /* TRUE if an FWNMI handler is present */
 
-static void pseries_shared_idle(void);
-static void pseries_dedicated_idle(void);
+static void pseries_shared_idle_sleep(void);
+static void pseries_dedicated_idle_sleep(void);
 
 struct mpic *pSeries_mpic;
 
@@ -236,14 +236,13 @@ static void __init pSeries_setup_arch(void)
                 vpa_init(boot_cpuid);
                 if (get_lppaca()->shared_proc) {
                         printk(KERN_INFO "Using shared processor idle loop\n");
-                        ppc_md.idle_loop = pseries_shared_idle;
+                        ppc_md.power_save = pseries_shared_idle_sleep;
                 } else {
                         printk(KERN_INFO "Using dedicated idle loop\n");
-                        ppc_md.idle_loop = pseries_dedicated_idle;
+                        ppc_md.power_save = pseries_dedicated_idle_sleep;
                 }
         } else {
                 printk(KERN_INFO "Using default idle loop\n");
-                ppc_md.idle_loop = default_idle;
         }
 
         if (firmware_has_feature(FW_FEATURE_LPAR))
@@ -393,136 +392,87 @@ static int __init pSeries_probe(int platform)
 
 DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
 
-static inline void dedicated_idle_sleep(unsigned int cpu)
-{
-        struct lppaca *plppaca = &lppaca[cpu ^ 1];
-
-        /* Only sleep if the other thread is not idle */
-        if (!(plppaca->idle)) {
-                local_irq_disable();
-
-                /*
-                 * We are about to sleep the thread and so wont be polling any
-                 * more.
-                 */
-                clear_thread_flag(TIF_POLLING_NRFLAG);
-                smp_mb__after_clear_bit();
-
-                /*
-                 * 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();
-                set_thread_flag(TIF_POLLING_NRFLAG);
-        } else {
-                /*
-                 * Give the HV an opportunity at the processor, since we are
-                 * not doing any work.
-                 */
-                poll_pending();
-        }
-}
-
-static void pseries_dedicated_idle(void)
+static void pseries_dedicated_idle_sleep(void)
 { 
         unsigned int cpu = smp_processor_id();
         unsigned long start_snooze;
         unsigned long *smt_snooze_delay = &__get_cpu_var(smt_snooze_delay);
-        set_thread_flag(TIF_POLLING_NRFLAG);
-
-        while (1) {
-                /*
-                 * Indicate to the HV that we are idle. Now would be
-                 * a good time to find other work to dispatch.
-                 */
-                get_lppaca()->idle = 1;
-
-                if (!need_resched()) {
-                        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();
-                }
 
-                get_lppaca()->idle = 0;
-                ppc64_runlatch_on();
+        /*
+         * Indicate to the HV that we are idle. Now would be
+         * a good time to find other work to dispatch.
+         */
+        get_lppaca()->idle = 1;
 
-                preempt_enable_no_resched();
-                schedule();
-                preempt_disable();
+        /*
+         * We come in with interrupts disabled, and need_resched()
+         * has been checked recently.  If we should poll for a little
+         * while, do so.
+         */
+        if (*smt_snooze_delay) {
+                start_snooze = get_tb() +
+                        *smt_snooze_delay * tb_ticks_per_usec;
+                local_irq_enable();
+                set_thread_flag(TIF_POLLING_NRFLAG);
 
-                if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
-                        cpu_die();
+                while (get_tb() < start_snooze) {
+                        if (need_resched() || cpu_is_offline(cpu))
+                                goto out;
+                        ppc64_runlatch_off();
+                        HMT_low();
+                        HMT_very_low();
+                }
+
+                HMT_medium();
+                clear_thread_flag(TIF_POLLING_NRFLAG);
+                smp_mb();
+                local_irq_disable();
+                if (need_resched() || cpu_is_offline(cpu))
+                        goto out;
         }
+
+        /*
+         * Cede if the other thread is not idle, so that it can
+         * go single-threaded.  If the other thread is idle,
+         * we ask the hypervisor if it has pending work it
+         * wants to do and cede if it does.  Otherwise we keep
+         * polling in order to reduce interrupt latency.
+         *
+         * Doing the cede when the other thread is active will
+         * result in this thread going dormant, meaning the other
+         * thread gets to run in single-threaded (ST) mode, which
+         * is slightly faster than SMT mode with this thread at
+         * very low priority.  The cede enables interrupts, which
+         * doesn't matter here.
+         */
+        if (!lppaca[cpu ^ 1].idle || poll_pending() == H_Pending)
+                cede_processor();
+
+out:
+        HMT_medium();
+        get_lppaca()->idle = 0;
 }
 
-static void pseries_shared_idle(void)
+static void pseries_shared_idle_sleep(void)
 {
         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.
-                 */
-                get_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();
-                }
-
-                get_lppaca()->idle = 0;
-                ppc64_runlatch_on();
+        /*
+         * Indicate to the HV that we are idle. Now would be
+         * a good time to find other work to dispatch.
+         */
+        get_lppaca()->idle = 1;
 
-                preempt_enable_no_resched();
-                schedule();
-                preempt_disable();
+        /*
+         * 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.
+         */
+        cede_processor();
 
-                if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
-                        cpu_die();
-        }
+        get_lppaca()->idle = 0;
 }
 
 static int pSeries_pci_probe_mode(struct pci_bus *bus)
diff --git a/include/asm-powerpc/hvcall.h b/include/asm-powerpc/hvcall.h
index 38ca9ad6110d..b72c04f3f551 100644
--- a/include/asm-powerpc/hvcall.h
+++ b/include/asm-powerpc/hvcall.h
@@ -9,6 +9,7 @@
 #define H_Closed        2       /* Resource closed */
 #define H_Constrained   4       /* Resource request constrained to max allowed */
 #define H_InProgress   14       /* Kind of like busy */
+#define H_Pending      17       /* returned from H_POLL_PENDING */
 #define H_Continue     18       /* Returned from H_Join on success */
 #define H_LongBusyStartRange   9900  /* Start of long busy range */
 #define H_LongBusyOrder1msec   9900  /* Long busy, hint that 1msec is a good time to retry */