[-V6,26/27] powerpc/THP: Enable THP on PPC64

Submitted by Aneesh Kumar K.V on April 22, 2013, 10:01 a.m.

Details

Message ID 1366624861-24948-27-git-send-email-aneesh.kumar@linux.vnet.ibm.com
State Superseded
Headers show

Commit Message

Aneesh Kumar K.V April 22, 2013, 10:01 a.m. 
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

We enable only if the we support 16MB page size.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/pgtable-ppc64.h |    3 +--
 arch/powerpc/mm/pgtable_64.c             |   28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

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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 156706b..e0c2d09 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;
+	/*
+	 * 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;
+
+	return 1;
+}
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 pmd_t pmdp_get_and_clear(struct mm_struct *mm,