David Gibson <dwg@xxxxxxxxxxx> writes:
> On Mon, Apr 29, 2013 at 01:21:49AM +0530, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>>
>> We enable only if the we support 16MB page size.
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>> ---
>> arch/powerpc/include/asm/pgtable-ppc64.h | 3 +--
>> arch/powerpc/mm/pgtable_64.c | 28 ++++++++++++++++++++++++++++
>> 2 files changed, 29 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h
>> index 97fc839..d65534b 100644
>> --- a/arch/powerpc/include/asm/pgtable-ppc64.h
>> +++ b/arch/powerpc/include/asm/pgtable-ppc64.h
>> @@ -426,8 +426,7 @@ static inline unsigned long pmd_pfn(pmd_t pmd)
>> return pmd_val(pmd) >> PTE_RPN_SHIFT;
>> }
>>
>> -/* We will enable it in the last patch */
>> -#define has_transparent_hugepage() 0
>> +extern int has_transparent_hugepage(void);
>> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>>
>> static inline int pmd_young(pmd_t pmd)
>> diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
>> index 54216c1..b742d6f 100644
>> --- a/arch/powerpc/mm/pgtable_64.c
>> +++ b/arch/powerpc/mm/pgtable_64.c
>> @@ -754,6 +754,34 @@ void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
>> return;
>> }
>>
>> +int has_transparent_hugepage(void)
>> +{
>> + if (!mmu_has_feature(MMU_FTR_16M_PAGE))
>> + return 0;
>> + /*
>> + * We support THP only if HPAGE_SHIFT is 16MB.
>> + */
>> + if (!HPAGE_SHIFT || (HPAGE_SHIFT != mmu_psize_defs[MMU_PAGE_16M].shift))
>> + return 0;
>
> Again, THP should not be dependent on the value of HPAGE_SHIFT. Just
> checking that mmu_psize_defsz[MMU_PAGE_16M].shift == 24 should be
> sufficient (i.e. that 16M hugepages are supported).
done
+ /*
+ * We support THP only if PMD_SIZE is 16MB.
+ */
+ if (mmu_psize_defs[MMU_PAGE_16M].shift != PMD_SHIFT)
+ return 0;
+ /*
>
>> + /*
>> + * We need to make sure that we support 16MB hugepage in a segement
>> + * with base page size 64K or 4K. We only enable THP with a PAGE_SIZE
>> + * of 64K.
>> + */
>> + /*
>> + * If we have 64K HPTE, we will be using that by default
>> + */
>> + if (mmu_psize_defs[MMU_PAGE_64K].shift &&
>> + (mmu_psize_defs[MMU_PAGE_64K].penc[MMU_PAGE_16M] == -1))
>> + return 0;
>> + /*
>> + * Ok we only have 4K HPTE
>> + */
>> + if (mmu_psize_defs[MMU_PAGE_4K].penc[MMU_PAGE_16M] == -1)
>> + return 0;
>
> Except you don't actually support THP on 4K base page size yet.
That is 64K linux page size and 4K HPTE . We do support that. The Linux
page size part is taken care by Kconfig.
>
>> +
>> + return 1;
>> +}
>> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>>
>> pmd_t pmdp_get_and_clear(struct mm_struct *mm,
>
-aneesh
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