Re: [RFC PATCH] x86, espfix: use spin_lock rather than mutex

[H. Peter Anvin]

On 05/18/2015 12:43 PM, Andy Lutomirski wrote:
> On 05/15/2015 12:27 AM, H. Peter Anvin wrote:
>> On 05/14/2015 11:54 PM, Ingo Molnar wrote:
>>>
>>> The only slightly subtle detail with that is to use alloc_pages_node()
>>> with the secondary CPU's node, to make sure the espfix stack is
>>> NUMA-local to the CPU that is going to use it.
>>>
>>
>> It doesn't hurt, although it isn't super critical as each page will be
>> shared among 64 CPUs.  The whole espfix stack is only a single cacheline
>> long.
>>
> 
> I don't think we actually need these pages allocated until we try to run
> user code.  Can we move this very late in initialization instead?
> 

Yes, we could, as long as it is run on each CPU before that CPU tries to
run user code.

	-hpa


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