Re: [PATCH] Do not force shutdown/reboot to boot cpu.

["H. Peter Anvin" <hpa@zytor.com>]

On 04/08/2013 08:57 AM, Ingo Molnar wrote:
> 
> I think the original commit:
> 
>   f96972f2dc63 kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()
> 
> actually regressed your 1024 CPU systems, and should possibly be reverted or fixed 
> in some other fashion - such as by migrating to the primary CPU (on architectures 
> that require that), instead of hotplug offlining every secondary CPU on every 
> architecture!
> 
> Alternatively, disable_nonboot_cpus() could perhaps be improved to down CPUs in 
> parallel: issue the CPU-down requests to every CPU, then wait for them to complete 
> - instead of the loop over every CPU?
> 
> This would be the conceptual counter part to parallel boot up of CPUs - something 
> SGI might be interested in as well?
> 

Migrating to the boot processor and then calling stop_machine() to
defang any other processors should be sufficient, no?

I don't know if there is any reason to deschedule all tasks?

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.