Re: [PATCH] x86: Accelerate copy_page with non-temporal in X86

[Borislav Petkov]

+ linux-nvdimm

Original mail at https://lkml.kernel.org/r/3f28adee-8214-fa8e-b368-eaf8b193469e@xxxxxxxxxx

On Tue, Apr 13, 2021 at 02:25:58PM +0800, Kemeng Shi wrote:
> I'm using AEP with dax_kmem drvier, and AEP is export as a NUMA node in

What is AEP?

> my system. I will move cold pages from DRAM node to AEP node with
> move_pages system call. With old "rep movsq', it costs 2030ms to move
> 1 GB pages. With "movnti", it only cost about 890ms to move 1GB pages.

So there's __copy_user_nocache() which does NT stores.

> -	ALTERNATIVE "jmp copy_page_regs", "", X86_FEATURE_REP_GOOD
> +	ALTERNATIVE_2 "jmp copy_page_regs", "", X86_FEATURE_REP_GOOD, \
> +                      "jmp copy_page_nt", X86_FEATURE_XMM2

This makes every machine which has sse2 do NT stores now. Which means
*every* machine practically.

The folks on linux-nvdimm@ should be able to give you a better idea what
to do.

HTH.

-- 
Regards/Gruss,
    Boris.

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