Re: [RFC PATCH 00/12] x86/mm: Implement lockless pgd_alloc()/pgd_free()

[H. Peter Anvin]

On 06/11/2015 07:07 AM, Ingo Molnar wrote:
> Waiman Long reported 'pgd_lock' contention on high CPU count systems and proposed
> moving pgd_lock on a separate cacheline to eliminate false sharing and to reduce
> some of the lock bouncing overhead.
>
> I think we can do much better: this series eliminates the pgd_list and makes
> pgd_alloc()/pgd_free() lockless.

This ties into a slightly different issue, which is how to deal 
*properly* with "special" PGDs like the 1:1 trampoline and the UEFI page 
tables.  These, too, should be able to incorporate, possibly more than 
once, page tables further down.

	-hpa

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