From: Joe Korty Date: Wed, 27 Aug 2008 14:35:06 +0000 (-0400) Subject: x86: make poll_idle behave more like the other idle methods X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=2c7e9fd4c6cb7f4b0bc7162e9a30847e51a1ca1b;p=deliverable%2Flinux.git x86: make poll_idle behave more like the other idle methods Make poll_idle() behave more like the other idle methods. 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 Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 7fc4d5b0a6a0..4e09d26748cf 100644 --- a/arch/x86/kernel/process.c +++ b/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(); } /*