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-rw-r--r--arch/powerpc/platforms/pseries/setup.c190
-rw-r--r--include/asm-powerpc/hvcall.h1
2 files changed, 71 insertions, 120 deletions
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 44d5c7f..213bf98 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 38ca9ad..b72c04f 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 */
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