[XFS] Radix tree based inode caching

One of the perpetual scaling problems XFS has is indexing it's incore
inodes. We currently uses hashes and the default hash sizes chosen can
only ever be a tradeoff between memory consumption and the maximum
realistic size of the cache.

As a result, anyone who has millions of inodes cached on a filesystem
needs to tunes the size of the cache via the ihashsize mount option to
allow decent scalability with inode cache operations.

A further problem is the separate inode cluster hash, whose size is based
on the ihashsize but is smaller, and so under certain conditions (sparse
cluster cache population) this can become a limitation long before the
inode hash is causing issues.

The following patchset removes the inode hash and cluster hash and
replaces them with radix trees to avoid the scalability limitations of the
hashes. It also reduces the size of the inodes by 3 pointers....

SGI-PV: 969561
SGI-Modid: xfs-linux-melb:xfs-kern:29481a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/fs/xfs/xfs_clnt.h b/fs/xfs/xfs_clnt.h
index f89196cb08d2..d16c1b971074 100644
--- a/fs/xfs/xfs_clnt.h
+++ b/fs/xfs/xfs_clnt.h
@@ -89,7 +89,6 @@ struct xfs_mount_args {
 #define XFSMNT_IDELETE          0x08000000      /* inode cluster delete */
 #define XFSMNT_SWALLOC          0x10000000      /* turn on stripe width
                                                  * allocation */
-#define XFSMNT_IHASHSIZE        0x20000000      /* inode hash table size */
 #define XFSMNT_DIRSYNC          0x40000000      /* sync creat,link,unlink,rename
                                                  * symlink,mkdir,rmdir,mknod */
 #define XFSMNT_FLAGS2           0x80000000      /* more flags set in flags2 */