path: root/arch
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authorHugh Dickins <hugh@veritas.com>2005-10-29 18:16:40 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-29 21:40:42 -0700
commit4c21e2f2441dc5fbb957b030333f5a3f2d02dea7 (patch)
tree1f76d33bb1d76221c6424bc5fed080a4f91349a6 /arch
parentb38c6845b695141259019e2b7c0fe6c32a6e720d (diff)
[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with a many-threaded application which concurrently initializes different parts of a large anonymous area. This patch corrects that, by using a separate spinlock per page table page, to guard the page table entries in that page, instead of using the mm's single page_table_lock. (But even then, page_table_lock is still used to guard page table allocation, and anon_vma allocation.) In this implementation, the spinlock is tucked inside the struct page of the page table page: with a BUILD_BUG_ON in case it overflows - which it would in the case of 32-bit PA-RISC with spinlock debugging enabled. Splitting the lock is not quite for free: another cacheline access. Ideally, I suppose we would use split ptlock only for multi-threaded processes on multi-cpu machines; but deciding that dynamically would have its own costs. So for now enable it by config, at some number of cpus - since the Kconfig language doesn't support inequalities, let preprocessor compare that with NR_CPUS. But I don't think it's worth being user-configurable: for good testing of both split and unsplit configs, split now at 4 cpus, and perhaps change that to 8 later. There is a benefit even for singly threaded processes: kswapd can be attacking one part of the mm while another part is busy faulting. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch')
4 files changed, 8 insertions, 6 deletions
diff --git a/arch/arm/mm/mm-armv.c b/arch/arm/mm/mm-armv.c
index 60f3e039bac..1221fdde176 100644
--- a/arch/arm/mm/mm-armv.c
+++ b/arch/arm/mm/mm-armv.c
@@ -229,6 +229,7 @@ void free_pgd_slow(pgd_t *pgd)
pte = pmd_page(*pmd);
+ pte_lock_deinit(pte);
diff --git a/arch/frv/mm/pgalloc.c b/arch/frv/mm/pgalloc.c
index 4eaec0f3525..2c67dfe5a6b 100644
--- a/arch/frv/mm/pgalloc.c
+++ b/arch/frv/mm/pgalloc.c
@@ -87,14 +87,14 @@ static inline void pgd_list_add(pgd_t *pgd)
if (pgd_list)
pgd_list->private = (unsigned long) &page->index;
pgd_list = page;
- page->private = (unsigned long) &pgd_list;
+ set_page_private(page, (unsigned long)&pgd_list);
static inline void pgd_list_del(pgd_t *pgd)
struct page *next, **pprev, *page = virt_to_page(pgd);
next = (struct page *) page->index;
- pprev = (struct page **) page->private;
+ pprev = (struct page **)page_private(page);
*pprev = next;
if (next)
next->private = (unsigned long) pprev;
diff --git a/arch/i386/mm/pgtable.c b/arch/i386/mm/pgtable.c
index dcdce2c6c53..39c099f15b5 100644
--- a/arch/i386/mm/pgtable.c
+++ b/arch/i386/mm/pgtable.c
@@ -188,19 +188,19 @@ static inline void pgd_list_add(pgd_t *pgd)
struct page *page = virt_to_page(pgd);
page->index = (unsigned long)pgd_list;
if (pgd_list)
- pgd_list->private = (unsigned long)&page->index;
+ set_page_private(pgd_list, (unsigned long)&page->index);
pgd_list = page;
- page->private = (unsigned long)&pgd_list;
+ set_page_private(page, (unsigned long)&pgd_list);
static inline void pgd_list_del(pgd_t *pgd)
struct page *next, **pprev, *page = virt_to_page(pgd);
next = (struct page *)page->index;
- pprev = (struct page **)page->private;
+ pprev = (struct page **)page_private(page);
*pprev = next;
if (next)
- next->private = (unsigned long)pprev;
+ set_page_private(next, (unsigned long)pprev);
void pgd_ctor(void *pgd, kmem_cache_t *cache, unsigned long unused)
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 02cf36e0331..9e5e39cea82 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -144,6 +144,7 @@ void destroy_context_skas(struct mm_struct *mm)
if(!proc_mm || !ptrace_faultinfo){
+ pte_lock_deinit(virt_to_page(mmu->last_page_table));
pte_free_kernel((pte_t *) mmu->last_page_table);