Messages in this thread | | | Date | Fri, 30 Aug 2019 15:53:04 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [v2 PATCH -mm] mm: account deferred split THPs into MemAvailable |
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On Wed, Aug 28, 2019 at 06:02:24PM +0200, Michal Hocko wrote: > > > > > > Any idea about a bad case? > > > > Not really. > > > > How bad you want it to get? How many processes share the page? Access > > pattern? Locking situation? > > Let's say how hard a regular user can make this?
It bumped to ~170 ms if each THP was mapped 5 times.
Adding ptl contention (tight loop of MADV_DONTNEED) in 3 processes that maps the page, the time to split bumped to ~740ms.
Overally, it's reasonable to take ~100ms per GB of huge pages as rule of thumb.
-- Kirill A. Shutemov
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