[patch 17/34] ia64: Use generic idle loop

Thomas Gleixner
2013-03-21T21:58:52Z

[-- Attachment #1: ia64-use-generic-idle-loop.patch --]
[-- Type: text/plain, Size: 4493 bytes --]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
---
arch/ia64/Kconfig | 1
arch/ia64/kernel/perfmon.c | 13 ++-----
arch/ia64/kernel/process.c | 83 +++++++++------------------------------------
arch/ia64/kernel/smpboot.c | 2 -
4 files changed, 23 insertions(+), 76 deletions(-)

Index: linux-2.6/arch/ia64/Kconfig
===================================================================
--- linux-2.6.orig/arch/ia64/Kconfig
+++ linux-2.6/arch/ia64/Kconfig
@@ -35,6 +35,7 @@ config IA64
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select GENERIC_IOMAP
select GENERIC_SMP_IDLE_THREAD
+ select GENERIC_IDLE_LOOP
select ARCH_INIT_TASK
select ARCH_TASK_STRUCT_ALLOCATOR
select ARCH_THREAD_INFO_ALLOCATOR
Index: linux-2.6/arch/ia64/kernel/perfmon.c
===================================================================
--- linux-2.6.orig/arch/ia64/kernel/perfmon.c
+++ linux-2.6/arch/ia64/kernel/perfmon.c
@@ -1322,8 +1322,6 @@ out:
}
EXPORT_SYMBOL(pfm_unregister_buffer_fmt);

-extern void update_pal_halt_status(int);
-
static int
pfm_reserve_session(struct task_struct *task, int is_syswide, unsigned int cpu)
{
@@ -1371,9 +1369,9 @@ pfm_reserve_session(struct task_struct *
cpu));

/*
- * disable default_idle() to go to PAL_HALT
+ * Force idle() into poll mode
*/
- update_pal_halt_status(0);
+ cpu_idle_poll_ctrl(true);

UNLOCK_PFS(flags);

@@ -1430,11 +1428,8 @@ pfm_unreserve_session(pfm_context_t *ctx
is_syswide,
cpu));

- /*
- * if possible, enable default_idle() to go into PAL_HALT
- */
- if (pfm_sessions.pfs_task_sessions == 0 && pfm_sessions.pfs_sys_sessions == 0)
- update_pal_halt_status(1);
+ /* Undo forced polling. Last session reenables pal_halt */
+ cpu_idle_poll_ctrl(false);

UNLOCK_PFS(flags);

Index: linux-2.6/arch/ia64/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/ia64/kernel/process.c
+++ linux-2.6/arch/ia64/kernel/process.c
@@ -209,41 +209,13 @@ do_notify_resume_user(sigset_t *unused,
local_irq_disable(); /* force interrupt disable */
}

-static int pal_halt = 1;
-static int can_do_pal_halt = 1;
-
static int __init nohalt_setup(char * str)
{
- pal_halt = can_do_pal_halt = 0;
+ cpu_idle_poll_ctrl(true);
return 1;
}
__setup("nohalt", nohalt_setup);

-void
-update_pal_halt_status(int status)
-{
- can_do_pal_halt = pal_halt && status;
-}
-
-/*
- * We use this if we don't have any better idle routine..
- */
-void
-default_idle (void)
-{
- local_irq_enable();
- while (!need_resched()) {
- if (can_do_pal_halt) {
- local_irq_disable();
- if (!need_resched()) {
- safe_halt();
- }
- local_irq_enable();
- } else
- cpu_relax();
- }
-}
-
#ifdef CONFIG_HOTPLUG_CPU
/* We don't actually take CPU down, just spin without interrupts. */
static inline void play_dead(void)
@@ -270,50 +242,29 @@ static inline void play_dead(void)
}
#endif /* CONFIG_HOTPLUG_CPU */

-void __attribute__((noreturn))
-cpu_idle (void)
+void arch_cpu_idle_dead(void)
{
- void (*mark_idle)(int) = ia64_mark_idle;
- int cpu = smp_processor_id();
+ play_dead();
+}

- /* endless idle loop with no priority at all */
- while (1) {
- rcu_idle_enter();
- if (can_do_pal_halt) {
- current_thread_info()->status &= ~TS_POLLING;
- /*
- * TS_POLLING-cleared state must be visible before we
- * test NEED_RESCHED:
- */
- smp_mb();
- } else {
- current_thread_info()->status |= TS_POLLING;
- }
+void arch_cpu_idle(void)
+{
+ void (*mark_idle)(int) = ia64_mark_idle;

- if (!need_resched()) {
- void (*idle)(void);
#ifdef CONFIG_SMP
- min_xtp();
+ min_xtp();
#endif
- rmb();
- if (mark_idle)
- (*mark_idle)(1);
-
- if (!idle)
- idle = default_idle;
- (*idle)();
- if (mark_idle)
- (*mark_idle)(0);
+ rmb();
+ if (mark_idle)
+ (*mark_idle)(1);
+
+ safe_halt();
+
+ if (mark_idle)
+ (*mark_idle)(0);
#ifdef CONFIG_SMP
- normal_xtp();
+ normal_xtp();
#endif
- }
- rcu_idle_exit();
- schedule_preempt_disabled();
- check_pgt_cache();
- if (cpu_is_offline(cpu))
- play_dead();
- }
}

void
Index: linux-2.6/arch/ia64/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/ia64/kernel/smpboot.c
+++ linux-2.6/arch/ia64/kernel/smpboot.c
@@ -455,7 +455,7 @@ start_secondary (void *unused)
preempt_disable();
smp_callin();

- cpu_idle();
+ cpu_startup_entry(CPUHP_ONLINE);
return 0;
}