David Gibson <dwg@xxxxxxxxxxx> writes: > On Thu, Apr 11, 2013 at 01:10:29PM +0530, Aneesh Kumar K.V wrote: >> David Gibson <dwg@xxxxxxxxxxx> writes: >> >> > On Thu, Apr 04, 2013 at 11:27:55AM +0530, Aneesh Kumar K.V wrote: >> >> From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> >> >> >> >> We now have pmd entries covering to 16MB range. To implement THP on powerpc, >> >> we double the size of PMD. The second half is used to deposit the pgtable (PTE page). >> >> We also use the depoisted PTE page for tracking the HPTE information. The information >> >> include [ secondary group | 3 bit hidx | valid ]. We use one byte per each HPTE entry. >> >> With 16MB hugepage and 64K HPTE we need 256 entries and with 4K HPTE we need >> >> 4096 entries. Both will fit in a 4K PTE page. >> >> >> >> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> >> >> --- >> >> arch/powerpc/include/asm/page.h | 2 +- >> >> arch/powerpc/include/asm/pgtable-ppc64-64k.h | 3 +- >> >> arch/powerpc/include/asm/pgtable-ppc64.h | 2 +- >> >> arch/powerpc/include/asm/pgtable.h | 240 ++++++++++++++++++++ >> >> arch/powerpc/mm/pgtable.c | 314 ++++++++++++++++++++++++++ >> >> arch/powerpc/mm/pgtable_64.c | 13 ++ >> >> arch/powerpc/platforms/Kconfig.cputype | 1 + >> >> 7 files changed, 572 insertions(+), 3 deletions(-) >> >> >> >> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h >> >> index 38e7ff6..b927447 100644 >> >> --- a/arch/powerpc/include/asm/page.h >> >> +++ b/arch/powerpc/include/asm/page.h >> >> @@ -40,7 +40,7 @@ >> >> #ifdef CONFIG_HUGETLB_PAGE >> >> extern unsigned int HPAGE_SHIFT; >> >> #else >> >> -#define HPAGE_SHIFT PAGE_SHIFT >> >> +#define HPAGE_SHIFT PMD_SHIFT >> > >> > That looks like it could break everything except the 64k page size >> > 64-bit base. >> >> How about > > It seems very dubious to me to have transparent hugepages enabled > without explicit hugepages in the first place. > IMHO once we have THP, we will not be using explicit hugepages unless we want 16GB pages. -aneesh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>