Skip to contentSkip to conversation

Disable scheduler debugging

PATCH In review Andi Kleen 6 participants 7 messages Jun 6, 2004

lore
Share & tools
lore

Andi Kleen

author
#0 lore raw

PATCH 1/1 Disable scheduler debugging

The domain scheduler spews out a lot of information at boot up, but it looks mostly redundant because it's just a transformation of what is in /proc/cpuinfo anyways. Also it is well tested now. Disable it.

kernel/sched.c renamed from kernel/sched.c-o +1 -1
diff -u linux/kernel/sched.c-o linux/kernel/sched.c
@@ -3641,7 +3641,7 @@
 #endif /* CONFIG_NUMA_SCHED */
 #endif /* ARCH_HAS_SCHED_DOMAIN */
 
-#define SCHED_DOMAIN_DEBUG
+#undef SCHED_DOMAIN_DEBUG
 #ifdef SCHED_DOMAIN_DEBUG
 void sched_domain_debug(void)
 {
#1 lore raw
Quoted 3 lines · Andi Kleen

The domain scheduler spews out a lot of information at boot up, but it looks mostly redundant because it's just a transformation of what is in /proc/cpuinfo anyways. Also it is well tested now. Disable it.

i'd rather keep it some more, there are still open issues and if there's a boot failure or early crash it makes it easier for us to see the actual domain setup. Also, the messages are KERN_DEBUG.

Ingo

#2 lore raw
Quoted 11 lines · Ingo Molnar
Quoted 3 lines · Andi Kleen

The domain scheduler spews out a lot of information at boot up, but it looks mostly redundant because it's just a transformation of what is in /proc/cpuinfo anyways. Also it is well tested now. Disable it.

i'd rather keep it some more, there are still open issues and if there's a boot failure or early crash it makes it easier for us to see the actual domain setup. Also, the messages are KERN_DEBUG.

Unfortunately there are just, flat-out, way too many kernel messages at boot-up. Making them KERN_DEBUG doesn't solve the fact that SMP boxes often overflow the printk buffer before you boot up to a useful userland that can record the dmesg.

The IO-APIC code is a _major_ offender in this area, but the CPU code is right up there as well.

Jeff

#3 lore raw
Quoted 7 lines · Jeff Garzik

Unfortunately there are just, flat-out, way too many kernel messages at boot-up. Making them KERN_DEBUG doesn't solve the fact that SMP boxes often overflow the printk buffer before you boot up to a useful userland that can record the dmesg.

The IO-APIC code is a _major_ offender in this area, but the CPU code is right up there as well.

How about the configurable log buffer size patch? I think Andrew still has that amongst his wares.

#4 lore raw
Quoted 8 lines · Zwane Mwaikambo
Quoted 5 lines · Jeff Garzik

Unfortunately there are just, flat-out, way too many kernel messages at boot-up. Making them KERN_DEBUG doesn't solve the fact that SMP boxes often overflow the printk buffer before you boot up to a useful userland that can record the dmesg.

Quoted 6 lines
Quoted 2 lines

The IO-APIC code is a _major_ offender in this area, but the CPU code is right up there as well.

How about the configurable log buffer size patch? I think Andrew still has that amongst his wares.

It's in mainline. That's no excuse for the voluminous logs, though... I'm a "1-2 lines per module" type of person :)

Jeff

#5 lore raw

On Sun, 06 Jun 2004 17:55:07 -0400 Jeff Garzik wrote:

| Zwane Mwaikambo wrote:
| > On Sun, 6 Jun 2004, Jeff Garzik wrote:
| > 
| > 
| >>Unfortunately there are just, flat-out, way too many kernel messages at
| >>boot-up.  Making them KERN_DEBUG doesn't solve the fact that SMP boxes
| >>often overflow the printk buffer before you boot up to a useful userland
| >>that can record the dmesg.
| >>
| >>The IO-APIC code is a _major_ offender in this area, but the CPU code is
| >>right up there as well.
| > 
| > 
| > How about the configurable log buffer size patch? I think Andrew still has
| > that amongst his wares.
| 
| It's in mainline.  That's no excuse for the voluminous logs, though... 
| I'm a "1-2 lines per module" type of person :)

It's mainline, both CONFIG and command-line settable.

I'm a "there's always some case where more info is needed" type of person. But it won't happen on the next boot.... especially if the log size is increased. :(

--
~Randy

#6 lore raw
In reply to Jeff Garzik
Quoted 5 lines · Jeff Garzik

Unfortunately there are just, flat-out, way too many kernel messages at boot-up. Making them KERN_DEBUG doesn't solve the fact that SMP boxes often overflow the printk buffer before you boot up to a useful userland that can record the dmesg.

The IO-APIC code is a _major_ offender in this area, but the CPU code is right up there as well.

neither of these are nearly as bad as the crypto code, it takes a HUGE kernel log to get any info from before that if you enable all the encryption modes.

David Lang

Signature · 3 lines
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan