one question about local timer interrupt on tickless system

[kevint324]

hi all,

I'm having a 2.6.34 tickless kernel on my machine and i disabled the irq balance and isolcpu1-7.
So the core1-7 are at idle state.

One thing i don't understand is the LOC interrupt number decreased from core1 to core7.
I don't know much about how the tickless works but it seems to me core1-7 are totally symmetric and should have similar LOC count.

Can anyone explain why?

Thanks
Kevin



# cat /proc/interrupts

           CPU0       CPU1       CPU2       CPU3       CPU4       CPU5       CPU6       CPU7       
  0:       1975          0          0          0          0          0          0          0   IO-APIC-edge      timer
  1:          8          0          0          0          0          0          0          0   IO-APIC-edge      i8042
  4:          2          0          0          0          0          0          0          0   IO-APIC-edge    
  8:          1          0          0          0          0          0          0          0   IO-APIC-edge      rtc0
  9:          0          0          0          0          0          0          0          0   IO-APIC-fasteoi   acpi
 12:        611          0          0          0          0          0          0          0   IO-APIC-edge      i8042
 18:          0          0          0          0          0          0          0          0   IO-APIC-fasteoi   mgapci:0000:04:00.0
 23:         45          0          0          0          0          0          0          0   IO-APIC-fasteoi   ehci_hcd:usb1
 27:    4380964          0          0          0          0          0          0          0   PCI-MSI-edge      ahci
 28:    7599868          0          0          0          0          0          0          0   PCI-MSI-edge      eth2
NMI:          0          0          0          0          0          0          0          0   Non-maskable interrupts
LOC:   43301104   27172170   22968917   20057679   14197661   12650651    8082516    9051005   Local timer interrupts
SPU:          0          0          0          0          0          0          0          0   Spurious interrupts
PMI:          0          0          0          0          0          0          0          0   Performance monitoring interrupts
PND:          0          0          0          0          0          0          0          0   Performance pending work
RES:     126033       4453         39         38         20         19         17         19   Rescheduling interrupts
CAL:          0        262        262        262        262        262        262        262   Function call interrupts
TLB:      88389         33         23          7          5          6          4          2   TLB shootdowns
TRM:          0          0          0          0          0          0          0          0   Thermal event interrupts
THR:          0          0          0          0          0          0          0          0   Threshold APIC interrupts
MCE:          0          0          0          0          0          0          0          0   Machine check exceptions
MCP:       1951       1951       1951       1951       1951       1951       1951       1951   Machine check polls
ERR:          7
MIS:          0

[kevint324]

CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7
LOC: 43301104 27172170 22968917 20057679 14197661 12650651 8082516 9051005 Local timer interrupts

make it more clear