| Date | Thu, 11 Jun 2015 14:30:15 +0200 | From | Vlastimil Babka <> | Subject | Re: [PATCHv6 36/36] thp: update documentation |
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On 06/03/2015 07:06 PM, Kirill A. Shutemov wrote: > The patch updates Documentation/vm/transhuge.txt to reflect changes in > THP design.
One thing I'm missing is info about the deferred splitting.
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > --- > Documentation/vm/transhuge.txt | 124 +++++++++++++++++++++++------------------ > 1 file changed, 69 insertions(+), 55 deletions(-) > > diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt > index 6b31cfbe2a9a..2352b12cae93 100644 > --- a/Documentation/vm/transhuge.txt > +++ b/Documentation/vm/transhuge.txt > @@ -35,10 +35,10 @@ miss is going to run faster. > > == Design == > > -- "graceful fallback": mm components which don't have transparent > - hugepage knowledge fall back to breaking a transparent hugepage and > - working on the regular pages and their respective regular pmd/pte > - mappings > +- "graceful fallback": mm components which don't have transparent hugepage > + knowledge fall back to breaking huge pmd mapping into table of ptes and, > + if nesessary, split a transparent hugepage. Therefore these components
necessary > + > +split_huge_page uses migration entries to stabilize page->_count and > +page->_mapcount.
Hm, what if there's some physical memory scanner taking page->_count pins? I think compaction shouldn't be an issue, but maybe some others?
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