[PATCH] make CONFIG_PARAVIRT require NO_HZ

[PATCH] make CONFIG_PARAVIRT require NO_HZ

[Chris Wright]

Given all the discussion, let's just require NO_HZ when
CONFIG_PARAVIRT.  Anyone object?

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---

--- a/arch/i386/Kconfig	Mon Mar 12 11:07:45 2007 -0700
+++ b/arch/i386/Kconfig	Mon Mar 12 16:53:14 2007 -0700
@@ -208,7 +208,7 @@ endchoice
 
 config PARAVIRT
 	bool "Paravirtualization support (EXPERIMENTAL)"
-	depends on EXPERIMENTAL
+	depends on EXPERIMENTAL && NO_HZ
 	depends on !(X86_VISWS || X86_VOYAGER)
 	help
 	  Paravirtualization is a way of running multiple instances of

Re: [PATCH] make CONFIG_PARAVIRT require NO_HZ

[Zachary Amsden]

Chris Wright wrote:
> Given all the discussion, let's just require NO_HZ when
> CONFIG_PARAVIRT.  Anyone object?
>
> Signed-off-by: Chris Wright <chrisw@sous-sol.org>
> ---
>
> --- a/arch/i386/Kconfig	Mon Mar 12 11:07:45 2007 -0700
> +++ b/arch/i386/Kconfig	Mon Mar 12 16:53:14 2007 -0700
> @@ -208,7 +208,7 @@ endchoice
>  
>  config PARAVIRT
>  	bool "Paravirtualization support (EXPERIMENTAL)"
> -	depends on EXPERIMENTAL
> +	depends on EXPERIMENTAL && NO_HZ
>  	depends on !(X86_VISWS || X86_VOYAGER)
>  	help
>  	  Paravirtualization is a way of running multiple instances of
>   

Thanks Chris!

Acked-by: Zachary Amsden <zach@vmware.com>
Acked-by: Zachary Amsden <zach@vmware.com>
Acked-by: Zachary Amsden <zach@vmware.com>

Sorry, I got excited.

Zach

Re: [PATCH] make CONFIG_PARAVIRT require NO_HZ

[Ingo Molnar]

* Chris Wright <chrisw@sous-sol.org> wrote:

> Given all the discussion, let's just require NO_HZ when 
> CONFIG_PARAVIRT.  Anyone object?

well ... why do we want this? I'd not mind making it default y if 
CONFIG_PARAVIRT is enabled, but why force it?

	Ingo

Re: [PATCH] make CONFIG_PARAVIRT require NO_HZ

[Andi Kleen]

On Friday 16 March 2007 11:55, Ingo Molnar wrote:
> * Chris Wright <chrisw@sous-sol.org> wrote:
> > Given all the discussion, let's just require NO_HZ when
> > CONFIG_PARAVIRT.  Anyone object?
>
> well ... why do we want this? I'd not mind making it default y if
> CONFIG_PARAVIRT is enabled, but why force it?

I guess because they don't want to debug and maintain two different timer code 
paths. It would be fine for me. !NOHZ will hopefully go away at some point
anyways and it clearly is important for virtualized environments.

Although I would prefer a select instead of a depends I think. Otherwise
the relationship will be quite unobvious.

-Andi

Re: [PATCH] make CONFIG_PARAVIRT require NO_HZ

[Ingo Molnar]

* Andi Kleen <ak@suse.de> wrote:

> Although I would prefer a select instead of a depends I think. 
> Otherwise the relationship will be quite unobvious.

yep.

	Ingo

Re: [PATCH] make CONFIG_PARAVIRT require NO_HZ

[Chris Wright]

* Andi Kleen (ak@suse.de) wrote:
> On Friday 16 March 2007 11:55, Ingo Molnar wrote:
> > * Chris Wright <chrisw@sous-sol.org> wrote:
> > > Given all the discussion, let's just require NO_HZ when
> > > CONFIG_PARAVIRT.  Anyone object?
> >
> > well ... why do we want this? I'd not mind making it default y if
> > CONFIG_PARAVIRT is enabled, but why force it?
> 
> I guess because they don't want to debug and maintain two different timer code 
> paths. It would be fine for me. !NOHZ will hopefully go away at some point
> anyways and it clearly is important for virtualized environments.

Yes, esp. considering the NO_IDLE_HZ problem.

> Although I would prefer a select instead of a depends I think. Otherwise
> the relationship will be quite unobvious.

I thought about that, NO_HZ is still a user-visible feature rather than
smth like library support.  That's typically been the dividing line
for depends vs. select.

thanks,
-chris

Re: [PATCH] make CONFIG_PARAVIRT require NO_HZ

[Andrew Morton]

On Thu, 15 Mar 2007 22:47:46 -0700 Chris Wright <chrisw@sous-sol.org> wrote:

> Given all the discussion, let's just require NO_HZ when
> CONFIG_PARAVIRT.  Anyone object?
> 
> Signed-off-by: Chris Wright <chrisw@sous-sol.org>
> ---
> 
> --- a/arch/i386/Kconfig	Mon Mar 12 11:07:45 2007 -0700
> +++ b/arch/i386/Kconfig	Mon Mar 12 16:53:14 2007 -0700
> @@ -208,7 +208,7 @@ endchoice
>  
>  config PARAVIRT
>  	bool "Paravirtualization support (EXPERIMENTAL)"
> -	depends on EXPERIMENTAL
> +	depends on EXPERIMENTAL && NO_HZ
>  	depends on !(X86_VISWS || X86_VOYAGER)
>  	help
>  	  Paravirtualization is a way of running multiple instances of

Apart from all the other fun, it seems that we need to merge
kconfig-abort-configuration-with-recursive-dependencies.patch, because

scripts/kconfig/conf -m arch/i386/Kconfig
Error: Found recursive dependency: PARAVIRT NO_HZ PARAVIRT
make[1]: *** [allmodconfig] Error 1
make: *** [allmodconfig] Error 2

This is due to your patch interacting with
make-config_paravirt-require-no_hz.patch:


From: Chris Wright <chrisw@sous-sol.org>

Require NO_HZ when CONFIG_PARAVIRT.

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Zachary Amsden <zach@vmware.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/i386/Kconfig |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN arch/i386/Kconfig~make-config_paravirt-require-no_hz arch/i386/Kconfig
--- a/arch/i386/Kconfig~make-config_paravirt-require-no_hz
+++ a/arch/i386/Kconfig
@@ -208,7 +208,7 @@ endchoice
 
 config PARAVIRT
 	bool "Paravirtualization support (EXPERIMENTAL)"
-	depends on EXPERIMENTAL
+	depends on EXPERIMENTAL && NO_HZ
 	depends on !(X86_VISWS || X86_VOYAGER)
 	select NO_HZ
 	help
_


I'll drop both of them while you guys sort it all out.