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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 /kernel/kexec.c
parentb38c6845b695141259019e2b7c0fe6c32a6e720d (diff)
downloadlinux-2.6.34-ux500-4c21e2f2441dc5fbb957b030333f5a3f2d02dea7.tar.gz
[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 'kernel/kexec.c')
-rw-r--r--kernel/kexec.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 36c5d9cd4cc..2c95848fbce 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -334,7 +334,7 @@ static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)
if (pages) {
unsigned int count, i;
pages->mapping = NULL;
- pages->private = order;
+ set_page_private(pages, order);
count = 1 << order;
for (i = 0; i < count; i++)
SetPageReserved(pages + i);
@@ -347,7 +347,7 @@ static void kimage_free_pages(struct page *page)
{
unsigned int order, count, i;
- order = page->private;
+ order = page_private(page);
count = 1 << order;
for (i = 0; i < count; i++)
ClearPageReserved(page + i);