Re: [PATCH] x86: Voluntary leave_mm before entering ACPI C3

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

Ingo Molnar wrote:
> 
> i dont think it's required for C3 to even turn off any portion of the 
> CPU - if an interrupt arrives after the C3 sequence is initiated but 
> just before dirty cachelines have been flushed then the CPU can just 
> return without touching anything (such as the TLB) - right? So i dont 
> think there's any implicit guarantee of TLB flushing (nor should there 
> be), but in practice, a good C3 sequence would (statistically) turn off 
> large portions of the CPU and hence the TLB as well.
> 

I think C3 guarantees that the cache contents stay intact, and thus it 
might make sense in some technology to preserve the TLB as well (being a 
kind of cache.)

Otherwise, what you say here of course is absolutely correct.

	-hpa