how to disable debugging in rawhide-kernel

[Satish Balay]

I guess the rawhide kernel has extra checks/debugging turned on -
which can slow things down.

Any idea what these are?

I'd like to disable these patches and rebuild the kernel [rawhide
kernels currently being more stable on my T40]

I'd appreciate any pointers.

Thanks,
Satish

[Wes Shull]

On Fri, 18 Feb 2005 12:27:36 -0600 (CST), Satish Balay
<balay(a)fastmail.fm&gt; wrote:
>  
>  I guess the rawhide kernel has extra checks/debugging turned on -
>  which can slow things down.
>  
>  Any idea what these are? 
Taking a quick gander through my /boot/config-2.6.10-1.1143_FC4...

#
# Kernel hacking
#
CONFIG_DEBUG_KERNEL=y
CONFIG_MAGIC_SYSRQ=y
# CONFIG_SCHEDSTATS is not set
CONFIG_DEBUG_SLAB=y
CONFIG_DEBUG_SPINLOCK=y
CONFIG_DEBUG_SPINLOCK_SLEEP=y
# CONFIG_DEBUG_KOBJECT is not set
CONFIG_DEBUG_HIGHMEM=y
CONFIG_DEBUG_BUGVERBOSE=y
CONFIG_DEBUG_INFO=y
# CONFIG_DEBUG_FS is not set
# CONFIG_FRAME_POINTER is not set
CONFIG_EARLY_PRINTK=y
CONFIG_DEBUG_STACKOVERFLOW=y
CONFIG_KPROBES=y
CONFIG_DEBUG_STACK_USAGE=y
CONFIG_DEBUG_PAGEALLOC=y
CONFIG_4KSTACKS=y

Probably just set all the CONFIG_DEBUG*=y there to =n.  I'm not sure
which would affect speed the most, but I'd guess disabling
CONFIG_DEBUG_SLAB will cut down most of the extraneous memory usage
(if that's as noticeable for you as it is for me on my 256 MB
machine).

The more debugs you keep on, though, the more chance you have of being
able to usefully report any problems...

(cc:ing you because I'm not sure I have my subscription set up to
allow posting from this address)

--wes

[Satish Balay]

On Fri, 18 Feb 2005, Wes Shull wrote:

>  Taking a quick gander through my /boot/config-2.6.10-1.1143_FC4...
Thanks for the pointer. I was earlier looking for difference in
patches in the spec file.

Looking at the diffs in config with 766_FC3 [latest FC3 update] & 1143
- I see the following:

CONFIG_DEBUG_SLAB=y
CONFIG_DEBUG_BUGVERBOSE=y
CONFIG_DEBUG_PAGEALLOC=y

I'll disable these - and see if it makes a difference. The others in
your list are:

CONFIG_DEBUG_KERNEL=y
CONFIG_DEBUG_HIGHMEM=y
CONFIG_DEBUG_SPINLOCK=y
CONFIG_DEBUG_SPINLOCK_SLEEP=y
CONFIG_DEBUG_INFO=y
CONFIG_DEBUG_STACKOVERFLOW=y
CONFIG_DEBUG_STACK_USAGE=y
CONFIG_DEBUG_PAGEALLOC=y

CONFIG_MAGIC_SYSRQ=y
CONFIG_EARLY_PRINTK=y
CONFIG_KPROBES=y
CONFIG_4KSTACKS=y

I guess I should try disabling some of these as well.

Satish

Aren't DEBUG_PAGEALLOC and DEBUG_SLAB incompatible? (was Re: how to disable debugging in rawhide-kernel)

[Barry K. Nathan]

On Fri, Feb 18, 2005 at 02:22:27PM -0600, Satish Balay wrote:
>  Thanks for the pointer. I was earlier looking for difference in
>  patches in the spec file.
>  
>  Looking at the diffs in config with 766_FC3 [latest FC3 update] & 1143
>  - I see the following:
>  
>  CONFIG_DEBUG_SLAB=y
>  CONFIG_DEBUG_BUGVERBOSE=y
>  CONFIG_DEBUG_PAGEALLOC=y 
Uhhh... Aren't CONFIG_DEBUG_SLAB and CONFIG_DEBUG_PAGEALLOC incompatible
with each other? At least, that's what I was told by none other than
Dave Jones himself (RH Bugzilla #144324, comment #15).

That reminds me, I have one FC3 system here running rawhide kernels, and
it keeps oopsing once every couple of days. Unfortunately I haven't had
a chance to set up a serial console on it again (I'll do that later
today), but I wonder if the combination of DEBUG_SLAB and
DEBUG_PAGEALLOC is why it's oopsing...

-Barry K. Nathan <barryn(a)pobox.com&gt;

Aren't DEBUG_PAGEALLOC and DEBUG_SLAB incompatible? (was Re: how to disable debugging in rawhide-kernel)

[Satish Balay]

On Fri, 18 Feb 2005, Barry K. Nathan wrote:
>  
>  Uhhh... Aren't CONFIG_DEBUG_SLAB and CONFIG_DEBUG_PAGEALLOC incompatible
>  with each other? At least, that's what I was told by none other than
>  Dave Jones himself (RH Bugzilla #144324, comment #15). 
Chagelog has the following entry:

* Sun Jan 23 2005 Dave Jones <davej(a)redhat.com&gt;

- Updated periodic slab debug check from Manfred.
- Enable PAGE_ALLOC debugging again, it should now be fixed.
- 2.6.11-rc2-bk1

Satish

Aren't DEBUG_PAGEALLOC and DEBUG_SLAB incompatible? (was Re: how to disable debugging in rawhide-kernel)

[Barry K. Nathan]

On Fri, Feb 18, 2005 at 03:47:27PM -0600, Satish Balay wrote:
>  Chagelog has the following entry:
>  
>  * Sun Jan 23 2005 Dave Jones <davej(a)redhat.com&gt;
>  
>  - Updated periodic slab debug check from Manfred.
>  - Enable PAGE_ALLOC debugging again, it should now be fixed.
>  - 2.6.11-rc2-bk1 
Doh! Thanks for setting me straight. (I was sleep-deprived and in a
hurry, so I forgot to check the changelog.)

-Barry K. Nathan <barryn(a)pobox.com&gt;