Re: [PATCH v2 3/7] mm: munlock: batch non-THP page isolation and munlock+putback using pagevec

[Mel Gorman <mgorman@suse.de>]

On Mon, Aug 19, 2013 at 02:23:38PM +0200, Vlastimil Babka wrote:
> Currently, munlock_vma_range() calls munlock_vma_page on each page in a loop,
> which results in repeated taking and releasing of the lru_lock spinlock for
> isolating pages one by one. This patch batches the munlock operations using
> an on-stack pagevec, so that isolation is done under single lru_lock. For THP
> pages, the old behavior is preserved as they might be split while putting them
> into the pagevec. After this patch, a 9% speedup was measured for munlocking
> a 56GB large memory area with THP disabled.
> 
> A new function __munlock_pagevec() is introduced that takes a pagevec and:
> 1) It clears PageMlocked and isolates all pages under lru_lock. Zone page stats
> can be also updated using the variant which assumes disabled interrupts.
> 2) It finishes the munlock and lru putback on all pages under their lock_page.
> Note that previously, lock_page covered also the PageMlocked clearing and page
> isolation, but it is not needed for those operations.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> Reviewed-by: Jorn Engel <joern@logfs.org>

Acked-by: Mel Gorman <mgorman@suse.de>

-- 
Mel Gorman
SUSE Labs

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