Messages in this thread Patch in this message | | | From | "Aneesh Kumar K.V" <> | Subject | Re: [PATCH 1/2] hugetlbfs: support split page table lock | Date | Wed, 04 Sep 2013 12:43:19 +0530 |
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Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> writes:
> Currently all of page table handling by hugetlbfs code are done under > mm->page_table_lock. So when a process have many threads and they heavily > access to the memory, lock contention happens and impacts the performance. > > This patch makes hugepage support split page table lock so that we use > page->ptl of the leaf node of page table tree which is pte for normal pages > but can be pmd and/or pud for hugepages of some architectures. > > ChangeLog v2: > - add split ptl on other archs missed in v1 > > Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > --- > arch/powerpc/mm/hugetlbpage.c | 6 ++- > arch/tile/mm/hugetlbpage.c | 6 ++- > include/linux/hugetlb.h | 20 ++++++++++ > mm/hugetlb.c | 92 ++++++++++++++++++++++++++----------------- > mm/mempolicy.c | 5 ++- > mm/migrate.c | 4 +- > mm/rmap.c | 2 +- > 7 files changed, 90 insertions(+), 45 deletions(-) > > diff --git v3.11-rc3.orig/arch/powerpc/mm/hugetlbpage.c v3.11-rc3/arch/powerpc/mm/hugetlbpage.c > index d67db4b..7e56cb7 100644 > --- v3.11-rc3.orig/arch/powerpc/mm/hugetlbpage.c > +++ v3.11-rc3/arch/powerpc/mm/hugetlbpage.c > @@ -124,6 +124,7 @@ static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp, > { > struct kmem_cache *cachep; > pte_t *new; > + spinlock_t *ptl; > > #ifdef CONFIG_PPC_FSL_BOOK3E > int i; > @@ -141,7 +142,8 @@ static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp, > if (! new) > return -ENOMEM; > > - spin_lock(&mm->page_table_lock); > + ptl = huge_pte_lockptr(mm, new); > + spin_lock(ptl);
Are you sure we can do that for ppc ? new = kmem_cache_zalloc(cachep, GFP_KERNEL|__GFP_REPEAT);
The page for new(pte_t) could be shared right ? which mean a deadlock ?
May be you should do it at the pmd level itself for ppc
> #ifdef CONFIG_PPC_FSL_BOOK3E > /* > * We have multiple higher-level entries that point to the same > @@ -174,7 +176,7 @@ static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp, > #endif > } > #endif > - spin_unlock(&mm->page_table_lock); > + spin_unlock(ptl); > return 0; > } >
-aneesh
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