linux-kernel - [patch] paravirt: allow NO_HZ, remove NO_IDLE

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Date:	Mon, 5 Mar 2007 12:29:28 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Andi Kleen <ak@...e.de>
Subject: [patch] paravirt: allow NO_HZ, remove NO_IDLE_HZ dependency

Subject: [patch] paravirt: remove NO_IDLE_HZ dependency
From: Ingo Molnar <mingo@...e.hu>

PARAVIRT forces CONFIG_NO_HZ off - this is bad and prevents sane 
paravirtual guests like KVM from being able to use dynticks-enabled 
Linux guests. Remove this. Vmi-timer needs to be updated properly to 
make use of dynticks.

furthermore, remove the mistaken turning on of NO_IDLE_HZ on 
x86+PARAVIRT kernels, it's an obsolete, limited form of dynticks.

must-have for v2.6.21.

Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/i386/Kconfig |   11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

Index: linux/arch/i386/Kconfig
===================================================================
--- linux.orig/arch/i386/Kconfig
+++ linux/arch/i386/Kconfig
@@ -224,7 +224,7 @@ config PARAVIRT
 
 config VMI
 	bool "VMI Paravirt-ops support"
-	depends on PARAVIRT && !NO_HZ
+	depends on PARAVIRT
 	default y
 	help
 	  VMI provides a paravirtualized interface to multiple hypervisors
@@ -1291,12 +1291,3 @@ config X86_TRAMPOLINE
 config KTIME_SCALAR
 	bool
 	default y
-
-config NO_IDLE_HZ
-	bool
-	depends on PARAVIRT
-	default y
-	help
-	  Switches the regular HZ timer off when the system is going idle.
-	  This helps a hypervisor detect that the Linux system is idle,
-	  reducing the overhead of idle systems.
-
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