Re: [patch] 2.4.1, 2.4.2-pre3: APIC lockups

[Andrew Morton]

"Maciej W. Rozycki" wrote:
> 
> Hi,
> 
>  After performing various tests I came to the following workaround for
> APIC lockups which people observe under IRQ load, mostly for networking
> stuff.

Works fine on the dual-PII.  No "Aieee!!!" messages at all.

After sending a few gigs across the ethernet, running
irq-whacker:

mnm:/usr/src/cptimer> cat /proc/interrupts
           CPU0       CPU1
  0:      77613      61869    IO-APIC-edge  timer
  1:        253        258    IO-APIC-edge  keyboard
  2:          0          0          XT-PIC  cascade
  8:          0          1    IO-APIC-edge  rtc
  9:          0          0          XT-PIC  acpi
 12:          0          0    IO-APIC-edge  PS/2 Mouse
 17:    5104855    3919759   IO-APIC-level  eth0
 18:       2334       2313   IO-APIC-level  ide2
NMI:     139418     139418
LOC:     139403     139402
ERR:        221
MIS:    5299867

And without irq-whacker:

mnm:/home/morton> cat /proc/interrupts
           CPU0       CPU1
  0:      55384      70899    IO-APIC-edge  timer
  1:          2          3    IO-APIC-edge  keyboard
  2:          0          0          XT-PIC  cascade
  8:          0          1    IO-APIC-edge  rtc
  9:          0          0          XT-PIC  acpi
 12:          0          0    IO-APIC-edge  PS/2 Mouse
 17:    2554705    2554064   IO-APIC-level  eth0
 18:       1814       1812   IO-APIC-level  ide2
NMI:     126220     126220
LOC:     126202     126201
ERR:         35
MIS:          0

Tell me, please: what tradeoffs are involved in this patch?
Obviously it works around a pretty fatal problem, but
what are we giving away?

Oh: and thanks :)

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