Messages in this thread | | | Subject | Re: [RFC] Reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings | From | Andi Kleen <> | Date | Wed, 23 Apr 2008 15:55:10 +0200 |
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Mel Gorman <mel@csn.ul.ie> writes:
> MAP_SHARED mappings on hugetlbfs reserve huge pages at mmap() time. This is > so that all future faults will be guaranteed to succeed. Applications are not > expected to use mlock() as this can result in poor NUMA placement. > > MAP_PRIVATE mappings do not reserve pages. This can result in an application > being SIGKILLed later if a large page is not available at fault time. This > makes huge pages usage very ill-advised in some cases as the unexpected > application failure is intolerable. Forcing potential poor placement with > mlock() is not a great solution either. > > This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings similar > to what happens for MAP_SHARED mappings.
This will break all applications that mmap more hugetlbpages than they actually use. How do you know these don't exist?
> Opinions?
Seems like a risky interface change to me.
-Andi
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