Re: [PATCH v2 7/7] mm: munlock: manual pte walk in fast path instead of follow_page_mask()

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On Mon, 19 Aug 2013 14:23:42 +0200 Vlastimil Babka <vbabka@xxxxxxx> wrote:

> Currently munlock_vma_pages_range() calls follow_page_mask() to obtain each
> struct page. This entails repeated full page table translations and page table
> lock taken for each page separately.
> 
> This patch attempts to avoid the costly follow_page_mask() where possible, by
> iterating over ptes within single pmd under single page table lock. The first
> pte is obtained by get_locked_pte() for non-THP page acquired by the initial
> follow_page_mask(). The latter function is also used as a fallback in case
> simple pte_present() and vm_normal_page() are not sufficient to obtain the
> struct page.

Patch #7 appears to provide significant performance gains, but the
improvement wasn't individually described here, unlike the other
patches.

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