[2.6 patch] let LOG_BUF_SHIFT default to 17

[2.6 patch] let LOG_BUF_SHIFT default to 17

[Adrian Bunk]

16 kB is often no longer enough for a normal boot of an UP system.

And even less when people e.g. use suspend.

17 seems to be a more reasonable default for current kernels on current 
hardware (it's just the default, anyone who is memory limited can 
still lower it).

Signed-off-by: Adrian Bunk <bunk@kernel.org>

---
f02213e3c1cb90ec1c66227f037110d489f30bfd 
diff --git a/init/Kconfig b/init/Kconfig
index 0eda68f..81a1255 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -272,17 +272,14 @@ config IKCONFIG_PROC
 config LOG_BUF_SHIFT
 	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 	range 12 21
-	default 17 if S390 || LOCKDEP
-	default 16 if X86_NUMAQ || IA64
-	default 15 if SMP
-	default 14
+	default 17
 	help
 	  Select kernel log buffer size as a power of 2.
-	  Defaults and Examples:
-	  	     17 => 128 KB for S/390
-		     16 => 64 KB for x86 NUMAQ or IA-64
-	             15 => 32 KB for SMP
-	             14 => 16 KB for uniprocessor
+	  Examples:
+	  	     17 => 128 KB
+		     16 => 64 KB
+	             15 => 32 KB
+	             14 => 16 KB
 		     13 =>  8 KB
 		     12 =>  4 KB
 

Re: [2.6 patch] let LOG_BUF_SHIFT default to 17

[Randy Dunlap]

On Tue, 29 Jan 2008 00:12:23 +0200 Adrian Bunk wrote:

> 16 kB is often no longer enough for a normal boot of an UP system.

s/16/64/ then agreed.

Acked-by: Randy Dunlap <randy.dunlap@oracle.com>


> And even less when people e.g. use suspend.
> 
> 17 seems to be a more reasonable default for current kernels on current 
> hardware (it's just the default, anyone who is memory limited can 
> still lower it).
> 
> Signed-off-by: Adrian Bunk <bunk@kernel.org>
> 
> ---
> f02213e3c1cb90ec1c66227f037110d489f30bfd 
> diff --git a/init/Kconfig b/init/Kconfig
> index 0eda68f..81a1255 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -272,17 +272,14 @@ config IKCONFIG_PROC
>  config LOG_BUF_SHIFT
>  	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
>  	range 12 21
> -	default 17 if S390 || LOCKDEP
> -	default 16 if X86_NUMAQ || IA64
> -	default 15 if SMP
> -	default 14
> +	default 17
>  	help
>  	  Select kernel log buffer size as a power of 2.
> -	  Defaults and Examples:
> -	  	     17 => 128 KB for S/390
> -		     16 => 64 KB for x86 NUMAQ or IA-64
> -	             15 => 32 KB for SMP
> -	             14 => 16 KB for uniprocessor
> +	  Examples:
> +	  	     17 => 128 KB
> +		     16 => 64 KB
> +	             15 => 32 KB
> +	             14 => 16 KB
>  		     13 =>  8 KB
>  		     12 =>  4 KB
>  
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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> 


---
~Randy

Re: [2.6 patch] let LOG_BUF_SHIFT default to 17

[Andi Kleen]

Adrian Bunk <bunk@kernel.org> writes:

> 16 kB is often no longer enough for a normal boot of an UP system.

Better would be to just disable by default/remove noisy messages
to make the kernel boot output shorter.

I think we got a lot of IMHO useless messages in there.

-Andi

Re: [2.6 patch] let LOG_BUF_SHIFT default to 17

[Adrian Bunk]

On Tue, Jan 29, 2008 at 07:35:00AM +0100, Andi Kleen wrote:
> Adrian Bunk <bunk@kernel.org> writes:
> 
> > 16 kB is often no longer enough for a normal boot of an UP system.
> 
> Better would be to just disable by default/remove noisy messages
> to make the kernel boot output shorter.
> 
> I think we got a lot of IMHO useless messages in there.

Nearly 25% of the messages in my dmesg come from ACPI.

Plus many other messages that cover these generic resources stuff (e.g. 
BIOS map or ioport/iomem reservations).

All of these tend to be of great help when debugging driver regressions, 
since diff'ing the dmesg's often is enough for determining whether it's 
a driver problem or a PCI/ACPI/whatever problem.

> -Andi

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

Re: [2.6 patch] let LOG_BUF_SHIFT default to 17

[Ingo Molnar]

* Adrian Bunk <bunk@kernel.org> wrote:

> 16 kB is often no longer enough for a normal boot of an UP system.
> 
> And even less when people e.g. use suspend.
> 
> 17 seems to be a more reasonable default for current kernels on 
> current hardware (it's just the default, anyone who is memory limited 
> can still lower it).

agreed - but i think the default should be even higher. Many reported 
dmesg's are truncated at the really interesting bits so it's a real 
problem in practice.

	Ingo

Re: [2.6 patch] let LOG_BUF_SHIFT default to 17

[Adrian Bunk]

On Fri, Feb 01, 2008 at 05:20:03PM +0100, Ingo Molnar wrote:
> 
> * Adrian Bunk <bunk@kernel.org> wrote:
> 
> > 16 kB is often no longer enough for a normal boot of an UP system.
> > 
> > And even less when people e.g. use suspend.
> > 
> > 17 seems to be a more reasonable default for current kernels on 
> > current hardware (it's just the default, anyone who is memory limited 
> > can still lower it).
> 
> agreed - but i think the default should be even higher. Many reported 
> dmesg's are truncated at the really interesting bits so it's a real 
> problem in practice.

17 is 128 kB.

Do we really have that many truncated dmesg's with LOG_BUF_SHIFT=17?

> 	Ingo

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

[2.6 patch] let LOG_BUF_SHIFT default to 17

[Adrian Bunk]

16 kB is often no longer enough for a normal boot of an UP system.

And even less when people e.g. use suspend.

17 seems to be a more reasonable default for current kernels on current 
hardware (it's just the default, anyone who is memory limited can 
still lower it).

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>

---

This patch has been sent on:
- 29 Jan 2008

f02213e3c1cb90ec1c66227f037110d489f30bfd 
diff --git a/init/Kconfig b/init/Kconfig
index 0eda68f..81a1255 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -272,17 +272,14 @@ config IKCONFIG_PROC
 config LOG_BUF_SHIFT
 	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 	range 12 21
-	default 17 if S390 || LOCKDEP
-	default 16 if X86_NUMAQ || IA64
-	default 15 if SMP
-	default 14
+	default 17
 	help
 	  Select kernel log buffer size as a power of 2.
-	  Defaults and Examples:
-	  	     17 => 128 KB for S/390
-		     16 => 64 KB for x86 NUMAQ or IA-64
-	             15 => 32 KB for SMP
-	             14 => 16 KB for uniprocessor
+	  Examples:
+	  	     17 => 128 KB
+		     16 => 64 KB
+	             15 => 32 KB
+	             14 => 16 KB
 		     13 =>  8 KB
 		     12 =>  4 KB