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
..
linux-2.6
quota
support
Kconfig
Makefile
Makefile-linux-2.6
xfs_acl.c
xfs_acl.h
xfs_ag.h
xfs_alloc_btree.c
xfs_alloc_btree.h
xfs_alloc.c
xfs_alloc.h
xfs_arch.h
xfs_attr_leaf.c
xfs_attr_leaf.h
xfs_attr_sf.h
xfs_attr.c
xfs_attr.h
xfs_behavior.c
xfs_behavior.h
xfs_bit.c
xfs_bit.h
xfs_bmap_btree.c
xfs_bmap_btree.h
xfs_bmap.c
xfs_bmap.h
xfs_btree.c
xfs_btree.h
xfs_buf_item.c
xfs_buf_item.h
xfs_cap.h
xfs_clnt.h
xfs_da_btree.c
xfs_da_btree.h
xfs_dfrag.c
xfs_dfrag.h
xfs_dinode.h
xfs_dir2_block.c
xfs_dir2_block.h
xfs_dir2_data.c
xfs_dir2_data.h
xfs_dir2_leaf.c
xfs_dir2_leaf.h
xfs_dir2_node.c
xfs_dir2_node.h
xfs_dir2_sf.c
xfs_dir2_sf.h
xfs_dir2_trace.c
xfs_dir2_trace.h
xfs_dir2.c
xfs_dir2.h
xfs_dir_leaf.c
xfs_dir_leaf.h
xfs_dir_sf.h
xfs_dir.c
xfs_dir.h
xfs_dmapi.h
xfs_dmops.c
xfs_error.c
xfs_error.h
xfs_extfree_item.c
xfs_extfree_item.h
xfs_fs.h
xfs_fsops.c
xfs_fsops.h
xfs_ialloc_btree.c
xfs_ialloc_btree.h
xfs_ialloc.c
xfs_ialloc.h
xfs_iget.c
xfs_imap.h
xfs_inode_item.c
xfs_inode_item.h
xfs_inode.c
xfs_inode.h
xfs_inum.h
xfs_iocore.c
xfs_iomap.c
xfs_iomap.h
xfs_itable.c
xfs_itable.h
xfs_log_priv.h
xfs_log_recover.c
xfs_log_recover.h
xfs_log.c
xfs_log.h
xfs_mac.h
xfs_macros.c
xfs_macros.h
xfs_mount.c
xfs_mount.h
xfs_qmops.c
xfs_quota.h
xfs_refcache.h
xfs_rename.c
xfs_rtalloc.c
xfs_rtalloc.h
xfs_rw.c
xfs_rw.h
xfs_sb.h
xfs_trans_ail.c
xfs_trans_buf.c
xfs_trans_extfree.c
xfs_trans_inode.c
xfs_trans_item.c
xfs_trans_priv.h
xfs_trans_space.h
xfs_trans.c
xfs_trans.h
xfs_types.h
xfs_utils.c
xfs_utils.h
xfs_vfsops.c
xfs_vnodeops.c
xfs.h