[RFC patch 5/7] thp, s390: thp pagetable pre-allocation for System z

Gerald Schaefer
2012-08-23T17:19:11Z

[-- Attachment #1: linux-3.5-thp-s390-pgtable.patch --]
[-- Type: text/plain, Size: 2201 bytes --]

This patch is part of the architecture backend for thp on System z.
It provides the pagetable pre-allocation functions pgtable_deposit()
and pgtable_withdraw(). Unlike other archs, s390 has no struct page *
as pgtable_t, but rather a pointer to the page table. So instead of
saving the pagetable pre-allocation list info inside the struct page,
it is being saved within the pagetable itself.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
---
arch/s390/include/asm/pgtable.h | 6 ++++++
arch/s390/mm/pgtable.c | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 44 insertions(+)

--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1166,6 +1166,12 @@ static inline pmd_t *pmd_offset(pud_t *p
#define pte_unmap(pte) do { } while (0)

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define __HAVE_ARCH_PGTABLE_DEPOSIT
+extern void pgtable_deposit(struct mm_struct *mm, pgtable_t pgtable);
+
+#define __HAVE_ARCH_PGTABLE_WITHDRAW
+extern pgtable_t pgtable_withdraw(struct mm_struct *mm);
+
static inline int pmd_trans_splitting(pmd_t pmd)
{
return pmd_val(pmd) & _SEGMENT_ENTRY_SPLIT;
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -883,4 +883,42 @@ void pmdp_splitting_flush(struct vm_area
smp_call_function(pmdp_splitting_flush_sync, NULL, 1);
}
}
+
+void pgtable_deposit(struct mm_struct *mm, pgtable_t pgtable)
+{
+ struct list_head *lh = (struct list_head *) pgtable;
+
+ assert_spin_locked(&mm->page_table_lock);
+
+ /* FIFO */
+ if (!mm->pmd_huge_pte)
+ INIT_LIST_HEAD(lh);
+ else
+ list_add(lh, (struct list_head *) mm->pmd_huge_pte);
+ mm->pmd_huge_pte = pgtable;
+}
+
+pgtable_t pgtable_withdraw(struct mm_struct *mm)
+{
+ struct list_head *lh;
+ pgtable_t pgtable;
+ pte_t *ptep;
+
+ assert_spin_locked(&mm->page_table_lock);
+
+ /* FIFO */
+ pgtable = mm->pmd_huge_pte;
+ lh = (struct list_head *) pgtable;
+ if (list_empty(lh))
+ mm->pmd_huge_pte = NULL;
+ else {
+ mm->pmd_huge_pte = (pgtable_t) lh->next;
+ list_del(lh);
+ }
+ ptep = (pte_t *) pgtable;
+ pte_val(*ptep) = _PAGE_TYPE_EMPTY;
+ ptep++;
+ pte_val(*ptep) = _PAGE_TYPE_EMPTY;
+ return pgtable;
+}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */