From 0723a69a63beec1ca6e792239ef75d0181387ef0 Mon Sep 17 00:00:00 2001 From: Benjamin LaHaise <bcrl@kvack.org> Date: Wed, 30 Jan 2008 13:33:13 +0100 Subject: [PATCH] x86: fix synchronize_rcu(): high latency on idle system an otherwise idle system takes about 3 ticks per network interface in unregister_netdev() due to multiple calls to synchronize_rcu(), which adds up to quite a few seconds for tearing down thousands of interfaces. By flushing pending rcu callbacks in the idle loop, the system makes progress hundreds of times faster. If this is indeed a sane thing to, it probably needs to be done for other architectures than x86. And yes, the network stack shouldn't call synchronize_rcu() quite so much, but fixing that is a little more involved. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/kernel/process_32.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 7a61b54649de..69a69c3f43bb 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -198,6 +198,9 @@ void cpu_idle(void) rmb(); idle = pm_idle; + if (rcu_pending(cpu)) + rcu_check_callbacks(cpu, 0); + if (!idle) idle = default_idle; -- 2.20.1