[patch 31/34] tile: Use generic idle loop

Thomas Gleixner
2013-03-21T21:54:22Z

[-- Attachment #1: tile-use-generic-idle-loop.patch --]
[-- Type: text/plain, Size: 2850 bytes --]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@tilera.com>
---
arch/tile/kernel/process.c | 61 ++++-----------------------------------------
arch/tile/kernel/smpboot.c | 2 -
2 files changed, 7 insertions(+), 56 deletions(-)

Index: linux-2.6/arch/tile/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/tile/kernel/process.c
+++ linux-2.6/arch/tile/kernel/process.c
@@ -40,13 +40,11 @@
#include <arch/abi.h>
#include <arch/sim_def.h>

-
/*
* Use the (x86) "idle=poll" option to prefer low latency when leaving the
* idle loop over low power while in the idle loop, e.g. if we have
* one thread per core and we want to get threads out of futex waits fast.
*/
-static int no_idle_nap;
static int __init idle_setup(char *str)
{
if (!str)
@@ -54,64 +52,17 @@ static int __init idle_setup(char *str)

if (!strcmp(str, "poll")) {
pr_info("using polling idle threads.\n");
- no_idle_nap = 1;
+ cpu_idle_poll_ctrl(true);
} else if (!strcmp(str, "halt"))
- no_idle_nap = 0;
- else
- return -1;
-
- return 0;
+ return 0;
+ return -1;
}
early_param("idle", idle_setup);

-/*
- * The idle thread. There's no useful work to be
- * done, so just try to conserve power and have a
- * low exit latency (ie sit in a loop waiting for
- * somebody to say that they'd like to reschedule)
- */
-void cpu_idle(void)
+void arch_cpu_idle(void)
{
- int cpu = smp_processor_id();
-
-
- current_thread_info()->status |= TS_POLLING;
-
- if (no_idle_nap) {
- while (1) {
- while (!need_resched())
- cpu_relax();
- schedule();
- }
- }
-
- /* endless idle loop with no priority at all */
- while (1) {
- tick_nohz_idle_enter();
- rcu_idle_enter();
- while (!need_resched()) {
- if (cpu_is_offline(cpu))
- BUG(); /* no HOTPLUG_CPU */
-
- local_irq_disable();
- __get_cpu_var(irq_stat).idle_timestamp = jiffies;
- current_thread_info()->status &= ~TS_POLLING;
- /*
- * TS_POLLING-cleared state must be visible before we
- * test NEED_RESCHED:
- */
- smp_mb();
-
- if (!need_resched())
- _cpu_idle();
- else
- local_irq_enable();
- current_thread_info()->status |= TS_POLLING;
- }
- rcu_idle_exit();
- tick_nohz_idle_exit();
- schedule_preempt_disabled();
- }
+ __get_cpu_var(irq_stat).idle_timestamp = jiffies;
+ _cpu_idle();
}

/*
Index: linux-2.6/arch/tile/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/tile/kernel/smpboot.c
+++ linux-2.6/arch/tile/kernel/smpboot.c
@@ -207,7 +207,7 @@ void __cpuinit online_secondary(void)
/* Set up tile-timer clock-event device on this cpu */
setup_tile_timer();

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

int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)