Hugh Dickins 4c21e2f244 [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>		2005-10-29 21:40:42 -07:00
..
cache.h
callback.c
cell.c
cell.h
cmservice.c
cmservice.h
dir.c
errors.h
file.c	[PATCH] mm: split page table lock	2005-10-29 21:40:42 -07:00
fsclient.c
fsclient.h
inode.c
internal.h
kafsasyncd.c
kafsasyncd.h
kafstimod.c
kafstimod.h
main.c
Makefile
misc.c
mntpt.c
mount.h
proc.c
server.c
server.h
super.c
super.h
transport.h
types.h
vlclient.c
vlclient.h
vlocation.c
vnode.c
vnode.h
volume.c
volume.h