diff options
| author | Hugh Dickins <hugh@veritas.com> | 2005-10-29 18:16:40 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-29 21:40:42 -0700 |
| commit | 4c21e2f2441dc5fbb957b030333f5a3f2d02dea7 (patch) | |
| tree | 1f76d33bb1d76221c6424bc5fed080a4f91349a6 /fs/afs | |
| parent | b38c6845b695141259019e2b7c0fe6c32a6e720d (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 'fs/afs')
| -rw-r--r-- | fs/afs/file.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/afs/file.c b/fs/afs/file.c index 0d576987ec6..4975c9c193d 100644 --- a/fs/afs/file.c +++ b/fs/afs/file.c @@ -291,8 +291,8 @@ static int afs_file_releasepage(struct page *page, gfp_t gfp_flags) cachefs_uncache_page(vnode->cache, page); #endif - pageio = (struct cachefs_page *) page->private; - page->private = 0; + pageio = (struct cachefs_page *) page_private(page); + set_page_private(page, 0); ClearPagePrivate(page); if (pageio) |