kernel-ark/fs/jfs
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
..
acl.c JFS: allow extended attributes to be set within a existing transaction 2005-09-01 09:02:43 -05:00
endian24.h
file.c
inode.c JFS: Fix sparse warnings, including endian error 2005-09-15 23:25:41 -05:00
jfs_acl.h JFS: allow extended attributes to be set within a existing transaction 2005-09-01 09:02:43 -05:00
jfs_btree.h
jfs_debug.c
jfs_debug.h
jfs_dinode.h
jfs_dmap.c JFS: Corrupted block map should not cause trap 2005-10-11 09:06:59 -05:00
jfs_dmap.h
jfs_dtree.c JFS: Fix i_blocks accounting when allocation fails 2005-07-26 09:29:13 -05:00
jfs_dtree.h
jfs_extent.c
jfs_extent.h
jfs_filsys.h [PATCH] disk quotas fail when /etc/mtab is symlinked to /proc/mounts 2005-09-07 16:57:23 -07:00
jfs_imap.c JFS: make special inodes play nicely with page balancing 2005-10-03 15:32:11 -05:00
jfs_imap.h
jfs_incore.h
jfs_inode.c
jfs_inode.h
jfs_lock.h
jfs_logmgr.c JFS: Improve sync barrier processing 2005-07-27 09:17:57 -05:00
jfs_logmgr.h JFS: Improve sync barrier processing 2005-07-27 09:17:57 -05:00
jfs_metapage.c [PATCH] mm: split page table lock 2005-10-29 21:40:42 -07:00
jfs_metapage.h
jfs_mount.c
jfs_superblock.h
jfs_txnmgr.c JFS: make special inodes play nicely with page balancing 2005-10-03 15:32:11 -05:00
jfs_txnmgr.h JFS: don't dereference tlck->ip from txUpdateMap 2005-09-20 14:58:11 -05:00
jfs_types.h
jfs_umount.c
jfs_unicode.c
jfs_unicode.h
jfs_uniupr.c
jfs_xattr.h JFS: Implement jfs_init_security 2005-09-01 09:05:39 -05:00
jfs_xtree.c JFS: make sure right-most xtree pages have header.next set to zero 2005-10-28 13:27:40 -05:00
jfs_xtree.h
Makefile
namei.c JFS: Implement jfs_init_security 2005-09-01 09:05:39 -05:00
resize.c
super.c JFS: make special inodes play nicely with page balancing 2005-10-03 15:32:11 -05:00
symlink.c [PATCH] Fix up symlink function pointers 2005-08-19 18:08:21 -07:00
xattr.c JFS: Implement jfs_init_security 2005-09-01 09:05:39 -05:00