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Date:   Wed, 14 Apr 2021 08:51:30 -0700
From:   Andi Kleen <ak@linux.intel.com>
To:     Yu Zhao <yuzhao@google.com>
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Subject: Re: [PATCH v2 00/16] Multigenerational LRU Framework
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>    2) It will not scan PTE tables under non-leaf PMD entries that do not
>       have the accessed bit set, when
>       CONFIG_HAVE_ARCH_PARENT_PMD_YOUNG=y.

This assumes  that workloads have reasonable locality. Could there
be a worst case where only one or two pages in each PTE are used,
so this PTE skipping trick doesn't work?

-Andi