Re: oprofile problem, 2.6 kernel

[William C. <wc...@nc...>]

Andraz Tori wrote:
> Na 1075312993, 2004-01-28 ob 19:03, je William Cohen napisal(a):
> 
>>Is there any information in /var/log/dmesg about APIC? Some laptops have 
>>balcklisted apic. If the local APIC isn't enabled oprofile falls back on 
>>the timer interrupt. Does the laptop match any the entries in 
>>linux/arch/i386/kernel/dmi_scan.c (dmi_blacklist)?
> 
> 
> I tried everything, but apic is simply not turned on. My notebook (and
> any of its components) is not listed in dmi_scan
> 
> At the bootup kernel just says: 
> No local APIC present or hardware disabled
> 
> I tired everything.. i have "Local APIC suport on uniprocessors"
> compiled into the kernel allright and "IO-APIC support on uniprocessors"
> also. I 've read it could also conflict powermanagment so i turned ACPI
> off and on, it didn't help. Should i try to turn APM on? I am compiling
> my own kernels, not using debian sources. 
> Any other idea how to tell kernel to use APIC? On what could it depend,
> is there some special kernel bootup option for turning it on ?  
> Everything worked fine on 2.4 kernel ...
> 
> Hmm now i got oprofile to say "oprofile: using NMI timer interrupt.",
> but still no counters.

It might be useful to a look at /proc/cpuinfo. Here is an example from a 
P4 that is running OProfile:

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 0
model name      : Intel(R) Pentium(R) 4 CPU 1500MHz
stepping        : 10
cpu MHz         : 1495.580
cache size      : 256 KB
physical id     : 0
siblings        : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge 
mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm
bogomips        : 2940.92


Look at is the "flags" line. Does it have "apic"? If is doesn't, you are 
out of luck for using the processor's performance monitoring hardware. 
The "apic" flag indicates a local interrupt controller is present. If 
the processor doesn't have that, then the software can't generate the 
performance monitoring hardware interrupts.

What is listed for "cpu_family", "model", and "stepping". It is possible 
that OProfile code isn't identifying the processors as a P4.


-Will