Re: Hang in sched_balance_self()

[Nick Piggin]

Jack Steiner wrote:
> Nick -
>
> The latest 2.6.12-rc5-mm2 tree fails to boot on some of the 64p
> SGI systems. The system hangs immediately after printing:
>
> 	...
> 	Inode-cache hash table entries: 8388608 (order: 12, 67108864 bytes)
> 	Mount-cache hash table entries: 1024
> 	Boot processor id 0x0/0x0
> 	Brought up 64 CPUs
> 	Total of 64 processors activated (118415.36 BogoMIPS).
>
>
> I have isolated the failure to cpu 0 hanging in sched_balance_self() during
> a fork (or clone).  The "while" loop at the end of function never 
> terminates, ie. sd is never NULL.
>
> Is this a problem that you have seen before. If not, I'll do some
> more digging & isolate the problem.

Hi Jack,
I have not seen this problem, however I don't think it has
had much testing with multilevel NUMA domains.

If you could do some more digging that would be great, however
I plan to get time on a 64-way IA64 next week and look at
some scheduler issues, so I'll keep this in mind if you haven't
made any progress.

Thanks,
Nick

--
SUSE Labs, Novell Inc.
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