Re: [PATCH v8 8/8] x86/tlb: do flush_tlb_kernel_range by 'invlpg'

[Andi Kleen]

On Tue, Jun 12, 2012 at 05:06:45PM +0800, Alex Shi wrote:
> This patch do flush_tlb_kernel_range by 'invlpg'. The performance pay
> and gain was analyzed in my patch (x86/flush_tlb: try flush_tlb_single
> one by one in flush_tlb_range). Now we move this logical into kernel
> part. The pay is multiple 'invlpg' execution cost, that is same. but
>  the gain(cost reducing of TLB entries refilling) is absoulutely
> increased.

The subtle point is whether INVLPG flushes global pages or not.
After some digging I found a sentence in the SDM that says it does.
So it may be safe.

What does it improve?

-Andi
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