Re: [PATCH, RFC 0/6] Avoid cache trashing on clearing huge/giganticpage

[H. Peter Anvin]

On 07/20/2012 05:50 AM, Kirill A. Shutemov wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
>
> Clearing a 2MB huge page will typically blow away several levels of CPU
> caches.  To avoid this only cache clear the 4K area around the fault
> address and use a cache avoiding clears for the rest of the 2MB area.
>
> It would be nice to test the patchset with more workloads. Especially if
> you see performance regression with THP.
>
> Any feedback is appreciated.
>
> Andi Kleen (6):
>    THP: Use real address for NUMA policy
>    mm: make clear_huge_page tolerate non aligned address
>    THP: Pass real, not rounded, address to clear_huge_page
>    x86: Add clear_page_nocache
>    mm: make clear_huge_page cache clear only around the fault address
>    x86: switch the 64bit uncached page clear to SSE/AVX v2

This is a mix of x86-specific and generic changes... does anyone mind if 
I put this into the -tip tree?

	-hpa


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

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