From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Wed, 08 Aug 2007 16:07:17 -0700 (PDT) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with SMTP id l78N78bm009951 for ; Wed, 8 Aug 2007 16:07:12 -0700 Date: Thu, 9 Aug 2007 09:07:07 +1000 From: David Chinner Subject: [PATCH 0 of 4] Radix tree based inode caching Message-ID: <20070808230706.GO12413810@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: xfs-dev Cc: xfs-oss 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.... -- Dave Chinner Principal Engineer SGI Australian Software Group