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authorNick Piggin <npiggin@kernel.dk>2010-08-18 04:37:39 +1000
committerAl Viro <viro@zeniv.linux.org.uk>2010-08-18 08:35:48 -0400
commit99b7db7b8ffd6bb755eb0a175596421a0b581cb2 (patch)
treecbaf57d252f0852f967d3fd5a5f87472964a01fe /fs/internal.h
parent6416ccb7899960868f5016751fb81bf25213d24f (diff)
fs: brlock vfsmount_lock
fs: brlock vfsmount_lock Use a brlock for the vfsmount lock. It must be taken for write whenever modifying the mount hash or associated fields, and may be taken for read when performing mount hash lookups. A new lock is added for the mnt-id allocator, so it doesn't need to take the heavy vfsmount write-lock. The number of atomics should remain the same for fastpath rlock cases, though code would be slightly slower due to per-cpu access. Scalability is not not be much improved in common cases yet, due to other locks (ie. dcache_lock) getting in the way. However path lookups crossing mountpoints should be one case where scalability is improved (currently requiring the global lock). The slowpath is slower due to use of brlock. On a 64 core, 64 socket, 32 node Altix system (high latency to remote nodes), a simple umount microbenchmark (mount --bind mnt mnt2 ; umount mnt2 loop 1000 times), before this patch it took 6.8s, afterwards took 7.1s, about 5% slower. Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/internal.h')
-rw-r--r--fs/internal.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/internal.h b/fs/internal.h
index 6a5c13a8066..a6910e91cee 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -9,6 +9,8 @@
* 2 of the License, or (at your option) any later version.
*/
+#include <linux/lglock.h>
+
struct super_block;
struct linux_binprm;
struct path;
@@ -70,7 +72,8 @@ extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int);
extern void __init mnt_init(void);
-extern spinlock_t vfsmount_lock;
+DECLARE_BRLOCK(vfsmount_lock);
+
/*
* fs_struct.c