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4c21e2f244
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> |
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| .. | ||
| acl.c | ||
| endian24.h | ||
| file.c | ||
| inode.c | ||
| jfs_acl.h | ||
| jfs_btree.h | ||
| jfs_debug.c | ||
| jfs_debug.h | ||
| jfs_dinode.h | ||
| jfs_dmap.c | ||
| jfs_dmap.h | ||
| jfs_dtree.c | ||
| jfs_dtree.h | ||
| jfs_extent.c | ||
| jfs_extent.h | ||
| jfs_filsys.h | ||
| jfs_imap.c | ||
| jfs_imap.h | ||
| jfs_incore.h | ||
| jfs_inode.c | ||
| jfs_inode.h | ||
| jfs_lock.h | ||
| jfs_logmgr.c | ||
| jfs_logmgr.h | ||
| jfs_metapage.c | ||
| jfs_metapage.h | ||
| jfs_mount.c | ||
| jfs_superblock.h | ||
| jfs_txnmgr.c | ||
| jfs_txnmgr.h | ||
| jfs_types.h | ||
| jfs_umount.c | ||
| jfs_unicode.c | ||
| jfs_unicode.h | ||
| jfs_uniupr.c | ||
| jfs_xattr.h | ||
| jfs_xtree.c | ||
| jfs_xtree.h | ||
| Makefile | ||
| namei.c | ||
| resize.c | ||
| super.c | ||
| symlink.c | ||
| xattr.c | ||