Re: Scheduler grouping failure; division by zero inselect_task_rq_fair

From: Peter Zijlstra
Date: Mon Nov 29 2010 - 06:50:25 EST


On Sun, 2010-11-28 at 20:14 +0000, Ben Hutchings wrote:

> [ 0.856002] Pid: 2, comm: kthreadd Not tainted 2.6.32-5-amd64 #1 W1100z/2100z

What's in that kernel? is that simply the latest .32-stable?

> [ 0.536554] CPU0 attaching sched-domain:
> [ 0.540004] domain 0: span 0-1 level MC
> [ 0.548002] groups: 0 1
> [ 0.560003] domain 1: span 0-3 level NODE
> [ 0.568002] groups:
> [ 0.574179] ERROR: domain->cpu_power not set
> [ 0.576002]
> [ 0.580002] ERROR: groups don't span domain->span
> [ 0.584004] CPU1 attaching sched-domain:
> [ 0.588007] domain 0: span 0-1 level MC
> [ 0.596002] groups: 1 0 (cpu_power = 1023)
> [ 0.612002] ERROR: parent span is not a superset of domain->span
> [ 0.616003] domain 1: span 1-3 level CPU
> [ 0.624002] groups: 1 (cpu_power = 2048) 2-3 (cpu_power = 2048)
> [ 0.644003] domain 2: span 0-3 level NODE
> [ 0.652004] groups: 1-3 (cpu_power = 4096)
> [ 0.668002] ERROR: domain->cpu_power not set
> [ 0.672002]
> [ 0.676002] ERROR: groups don't span domain->span
> [ 0.680004] CPU2 attaching sched-domain:
> [ 0.684003] domain 0: span 2-3 level MC
> [ 0.692003] groups: 2 3
> [ 0.704003] domain 1: span 1-3 level CPU
> [ 0.712003] groups: 2-3 (cpu_power = 2048) 1 (cpu_power = 2048)
> [ 0.736003] domain 2: span 0-3 level NODE
> [ 0.744003] groups: 1-3 (cpu_power = 4096)
> [ 0.760003] ERROR: domain->cpu_power not set
> [ 0.764003]
> [ 0.768003] ERROR: groups don't span domain->span
> [ 0.772004] CPU3 attaching sched-domain:
> [ 0.776003] domain 0: span 2-3 level MC
> [ 0.784003] groups: 3 2
> [ 0.794183] domain 1: span 1-3 level CPU
> [ 0.800003] groups: 2-3 (cpu_power = 2048) 1 (cpu_power = 2048)
> [ 0.822183] domain 2: span 0-3 level NODE
> [ 0.828003] groups: 1-3 (cpu_power = 4096)
> [ 0.842180] ERROR: domain->cpu_power not set
> [ 0.844003]
> [ 0.848003] ERROR: groups don't span domain->span

Hrm that smells like the architecture topology setup is wrecked, looks
like the NUMA setup is bonkers.

I really know very little about that code, I think Tejun recently poked
at that in an attempt to merge 32 and 64bit x86.

Also, its very weird CPU0 only gets to have 2 domains, while the other
3 get 3 domains..

Ingo, who knows this stuff?
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