Re: SMP interrupt wierdness in Linux 2.6.8.1 - Interrupt Load Balancing not working

I just have almost the same config ASUS-P2BD with 2xPIII 450MHz
with the same symptoms, minus the running processes problem,
plus one more suspect IRQ9 shared by most of PCI devices???

I should give 2.6.9 a try with more careful config.

Did you tried 2.6.9?
Did you have the shared IRQ trouble?

Note that in my case I have effectively
2 runnings processes at a time.
Using top did you see the load of the 2 distinct CPU like this.

My favourite test to check if I am effectively using both CPU
is to run a simple multi-threaded C program that try to put
one thread to SCHED_FIFO with max priority if your machine
booted with one proc or could only use one as soon as you run
the program your box will apparently freeze until the 
SCHED_FIFO thread terminates.

If your box is not freezing you will be able to see
(with top for example) that 1 processor is 100% used
by the FIFO process.


----------------------
top - 20:41:54 up  1:14,  8 users,  load average: 0.39, 0.36, 0.32
Tasks: 106 total,   3 running, 102 sleeping,   0 stopped,   1 zombie
 Cpu0 : 22.0% us,  3.6% sy,  0.0% ni, 74.0% id,  0.0% wa,  0.4% hi, 0.0%
si
 Cpu1 : 22.5% us,  3.8% sy,  0.0% ni, 73.8% id,  0.0% wa,  0.0% hi, 
0.0% si
Mem:    449300k total,   416836k used,    32464k free,    45004k buffers

-----------------------

cat /proc/interrupts
           CPU0       CPU1
  0:    4068279         12    IO-APIC-edge  timer
  1:       9892          0    IO-APIC-edge  i8042
  2:          0          0          XT-PIC  cascade
  5:       5344          1    IO-APIC-edge  SoundBlaster
  7:          1          1    IO-APIC-edge  parport0
  8:          1          0    IO-APIC-edge  rtc
  9:     229563          1   IO-APIC-level  sym53c8xx, sym53c8xx,
uhci_hcd, aic7xxx, eth0 11:     238198          1   IO-APIC-level  
r128@PCI:1:0:0
 12:     119151          0    IO-APIC-edge  i8042
NMI:          0          0
LOC:    4068215    4068222
ERR:          0
MIS:          0


Le ven 29/10/2004 à 10:07, Lars Michael Jogbäck a écrit :
> Hello,
> 
> I've recently upgraded my SMP machine (2xPIII-500 on Asus P2B-D)
> from Linux 2.4 to Linux 2.6.8.1 and now it seem's that the machine
> only routes interrupts to one CPU. When loading the machine and
> running top, I still only have seen 1 process in "Running" state
> at the time. Should this be 2?
> 
> I have CONFIG_IRQBALANCE=y and of course CONFIG_SMP=y
> 
> lm@cleopatra:~$ cat /proc/interrupts
>            CPU0       CPU1
>   0:   36751142         16    IO-APIC-edge  timer
>   1:          9          1    IO-APIC-edge  i8042
>   2:          0          0          XT-PIC  cascade
>   8:          3          0    IO-APIC-edge  rtc
>  14:     273037          1    IO-APIC-edge  ide0
>  15:       1189          0    IO-APIC-edge  ide1
>  16:       8561          1   IO-APIC-level  sym53c8xx
>  17:      40698          1   IO-APIC-level  sym53c8xx
>  18:     110871          8   IO-APIC-level  ide2, ide3, ide4, ide5
>  19:     219831          0   IO-APIC-level  eth0
> NMI:          0          0
> LOC:   36752415   36752416
> ERR:          0
> MIS:        245
> 
> When running 2.4 the interrupts was distributed between the two CPUs.
> 
> The CPU's are indentical:
> lm@cleopatra:~$ cat /proc/cpuinfo
> processor       : 0
> vendor_id       : GenuineIntel
> cpu family      : 6
> model           : 7
> model name      : Pentium III (Katmai)
> stepping        : 3
> cpu MHz         : 501.328
> cache size      : 512 KB
> 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 mmx fxsr sse
> bogomips        : 989.18
> 
> processor       : 1
> vendor_id       : GenuineIntel
> cpu family      : 6
> model           : 7
> model name      : Pentium III (Katmai)
> stepping        : 3
> cpu MHz         : 501.328
> cache size      : 512 KB
> 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 mmx fxsr sse
> bogomips        : 999.42
> 
> Is there anyone out there who have an idea on where to start looking?
> 
> Best Regards,
> /LM
> 
> 
> 
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-- 
Eric NOULARD
E-mail: [email protected]