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    SubjectRe: [v3,2/3] powerpc: get hugetlbpage handling more generic
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    Le 24/11/2016 à 06:23, Scott Wood a écrit :
    > On Wed, Sep 21, 2016 at 10:11:54AM +0200, Christophe Leroy wrote:
    >> Today there are two implementations of hugetlbpages which are managed
    >> by exclusive #ifdefs:
    >> * FSL_BOOKE: several directory entries points to the same single hugepage
    >> * BOOK3S: one upper level directory entry points to a table of hugepages
    >>
    >> In preparation of implementation of hugepage support on the 8xx, we
    >> need a mix of the two above solutions, because the 8xx needs both cases
    >> depending on the size of pages:
    >> * In 4k page size mode, each PGD entry covers a 4M bytes area. It means
    >> that 2 PGD entries will be necessary to cover an 8M hugepage while a
    >> single PGD entry will cover 8x 512k hugepages.
    >> * In 16 page size mode, each PGD entry covers a 64M bytes area. It means
    >> that 8x 8M hugepages will be covered by one PGD entry and 64x 512k
    >> hugepages will be covers by one PGD entry.
    >>
    >> This patch:
    >> * removes #ifdefs in favor of if/else based on the range sizes
    >> * merges the two huge_pte_alloc() functions as they are pretty similar
    >> * merges the two hugetlbpage_init() functions as they are pretty similar
    >>
    >> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
    >> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    >
    > With this patch on e6500, running the hugetlb testsuite results in the
    > system hanging in a storm of OOM killer invocations (I'll try to debug
    > more deeply later). This patch also changes the default hugepage size on
    > FSL book3e from 4M to 16M.
    >

    Regarding the default hugepage size, it is a result of the merge of the
    two hugetlbpage_init().
    Should I add an ifdef to get 4M on FSL book3e by default ?
    What's the reason for selecting different hugepage sizes depending on
    the CPU ? I thought default size was selected based on what was existing.

    What testsuite do you run exactly ?

    Christophe

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