Naoya Horiguchi <n-horigu...@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 v3: > - disable split ptl for ppc with USE_SPLIT_PTLOCKS_HUGETLB. > - remove replacement in some architecture dependent code. This is justified > because an allocation of pgd/pud/pmd/pte entry can race with other > allocation, not with read/write access, so we can use different locks. > http://thread.gmane.org/gmane.linux.kernel.mm/106292/focus=106458 > > ChangeLog v2: > - add split ptl on other archs missed in v1 > - drop changes on arch/{powerpc,tile}/mm/hugetlbpage.c > > Signed-off-by: Naoya Horiguchi <n-horigu...@ah.jp.nec.com> > --- > include/linux/hugetlb.h | 20 +++++++++++ > include/linux/mm_types.h | 2 ++ > mm/hugetlb.c | 92 > +++++++++++++++++++++++++++++------------------- > mm/mempolicy.c | 5 +-- > mm/migrate.c | 4 +-- > mm/rmap.c | 2 +- > 6 files changed, 84 insertions(+), 41 deletions(-) > > diff --git v3.11-rc3.orig/include/linux/hugetlb.h > v3.11-rc3/include/linux/hugetlb.h > index 0393270..5cb8a4e 100644 > --- v3.11-rc3.orig/include/linux/hugetlb.h > +++ v3.11-rc3/include/linux/hugetlb.h > @@ -80,6 +80,24 @@ extern const unsigned long hugetlb_zero, hugetlb_infinity; > extern int sysctl_hugetlb_shm_group; > extern struct list_head huge_boot_pages; > > +#if USE_SPLIT_PTLOCKS_HUGETLB > +#define huge_pte_lockptr(mm, ptep) ({__pte_lockptr(virt_to_page(ptep)); }) > +#else /* !USE_SPLIT_PTLOCKS_HUGETLB */ > +#define huge_pte_lockptr(mm, ptep) ({&(mm)->page_table_lock; }) > +#endif /* USE_SPLIT_PTLOCKS_HUGETLB */ > + > +#define huge_pte_offset_lock(mm, address, ptlp) \ > +({ \ > + pte_t *__pte = huge_pte_offset(mm, address); \ > + spinlock_t *__ptl = NULL; \ > + if (__pte) { \ > + __ptl = huge_pte_lockptr(mm, __pte); \ > + *(ptlp) = __ptl; \ > + spin_lock(__ptl); \ > + } \ > + __pte; \ > +})
why not a static inline function ? > + > /* arch callbacks */ > > pte_t *huge_pte_alloc(struct mm_struct *mm,> @@ -164,6 +182,8 @@ static > inline void __unmap_hugepage_range(struct mmu_gather *tlb, > BUG(); > } > > +#define huge_pte_lockptr(mm, ptep) 0 > + > #endif /* !CONFIG_HUGETLB_PAGE */ > > #define HUGETLB_ANON_FILE "anon_hugepage" > diff --git v3.11-rc3.orig/include/linux/mm_types.h > v3.11-rc3/include/linux/mm_types.h > index fb425aa..cfb8c6f 100644 > --- v3.11-rc3.orig/include/linux/mm_types.h > +++ v3.11-rc3/include/linux/mm_types.h > @@ -24,6 +24,8 @@ > struct address_space; > > #define USE_SPLIT_PTLOCKS (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS) > +#define USE_SPLIT_PTLOCKS_HUGETLB \ > + (USE_SPLIT_PTLOCKS && !defined(CONFIG_PPC)) > Is that a common pattern ? Don't we generally use HAVE_ARCH_SPLIT_PTLOCKS in arch config file ? Also are we sure this is only an issue with PPC ? -aneesh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
