Re: 2.6.1 and irq balancing

[Ethan Weinstein]

Nakajima, Jun wrote:

> > Admittedly, the machine's load was not high when I took this sample.
> > However, creating a great deal of load does not change these statistics 
> > at all.  Being that there are patches available for 2.4.x kernels to 
> > fix this, I don't think this at all by design, but what do I know? =)
> >  

> 2.6 kernels don't need a patch to it as far as I understand. Are you
> saying that with significant amount of load, you did not see any
> distribution of interrupts? Today's threshold in the kernel is high
> because we found moving around interrupts frequently rather hurt the
> cache and thus lower the performance compared to "do nothing". Can you
> try to create significant load with your network (eth0 and eh1) and see
> what happens? 
>
> Jun 

Here's the situation two days later, I created some brief periods of 
high load on eth1 and I see we have some change:


           CPU0       CPU1       CPU2       CPU3
  0:  184932542          0    2592511          0    IO-APIC-edge  timer
  1:       1875          0          0          0    IO-APIC-edge  i8042
  2:          0          0          0          0          XT-PIC  cascade
  3:    3046103          0          0          0    IO-APIC-edge  serial
  8:          2          0          0          0    IO-APIC-edge  rtc
  9:          0          0          0          0   IO-APIC-level  acpi
 14:         76          0          0          0    IO-APIC-edge  ide0
 16:    2978264          0          0          0   IO-APIC-level  sym53c8xx
 22:    7838940          0          0          0   IO-APIC-level  eth0
 48:     916078          0     125150          0   IO-APIC-level  aic79xx
 49:    1099375          0          0          0   IO-APIC-level  aic79xx
 54:   51484241        316   50560879        279   IO-APIC-level  eth1
NMI:          0          0          0          0
LOC:  187530735  187530988  187530981  187530986
ERR:          0
MIS:          0


My argument is (see below).  This is an old 2x pentium2 @400, also 
running 2.6, an old Compaq Proliant to be exact.  This machine obviously 
has no HT, so why the balanced load?


           CPU0       CPU1
  0: 1066522197 1117196193    IO-APIC-edge  timer
  1:         42         19    IO-APIC-edge  i8042
  2:          0          0          XT-PIC  cascade
  5:   23523428   23510845   IO-APIC-level  TLAN
  8:          0          4    IO-APIC-edge  rtc
  9:         15         15   IO-APIC-level  sym53c8xx
 10:    6874323    6809042   IO-APIC-level  sym53c8xx
 11:    7545802    7509034   IO-APIC-level  ida0
 14:          8          2    IO-APIC-edge  ide0
NMI:          0          0
LOC: 2183867261 2183867237
ERR:          0
MIS:          0



Ethan
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