From: Joe Korty Currently, poll_idle() returns immediately. The other idle methods all wait indefinately for some condition to come true before returning. poll_idle should emulate these other methods and also wait for a return condition, in this case, for need_resched() to become 'true'. Without this delay the idle loop spends all of its time in the outer loop that calls poll_idle. This outer loop, these days, does real work, some of it under rcu locks. That work should only be done when idle is entered and when idle exits, not continuously while idle is spinning. Signed-off-by: Joe Korty Cc: Ingo Molnar Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- arch/x86/kernel/process.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff -puN arch/x86/kernel/process.c~x86-make-poll_idle-behave-more-like-the-other-idle-methods arch/x86/kernel/process.c --- a/arch/x86/kernel/process.c~x86-make-poll_idle-behave-more-like-the-other-idle-methods +++ a/arch/x86/kernel/process.c @@ -185,7 +185,8 @@ static void mwait_idle(void) static void poll_idle(void) { local_irq_enable(); - cpu_relax(); + while(!need_resched()) + cpu_relax(); } /* _