uml: eliminate interrupts in the idle loop
Now, the idle loop now longer needs SIGALRM firing - it can just sleep for the
requisite amount of time and fake a timer interrupt when it finishes.
Any use of ITIMER_REAL now goes away. disable_timer only turns off
ITIMER_VIRTUAL. switch_timers is no longer needed, so it, and all calls, goes
away.
disable_timer now returns the amount of time remaining on the timer.
default_idle uses this to tell idle_sleep how long to sleep. idle_sleep will
call alarm_handler if nanosleep returns 0, which is the case if it didn't
return early due to an interrupt. Otherwise, it just returns.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index aef494b..0eae00b 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -235,6 +235,8 @@
void default_idle(void)
{
+ unsigned long long nsecs;
+
while(1) {
/* endless idle loop with no priority at all */
@@ -246,9 +248,8 @@
schedule();
tick_nohz_stop_sched_tick();
- switch_timers(1);
- idle_sleep(10);
- switch_timers(0);
+ nsecs = disable_timer();
+ idle_sleep(nsecs);
tick_nohz_restart_sched_tick();
}
}