From 2a82b8be8a8dacb48cb7371449a7a9daa558b4a8 Mon Sep 17 00:00:00 2001 From: David Chinner Date: Wed, 11 Jul 2007 11:09:12 +1000 Subject: [XFS] Concurrent Multi-File Data Streams In media spaces, video is often stored in a frame-per-file format. When dealing with uncompressed realtime HD video streams in this format, it is crucial that files do not get fragmented and that multiple files a placed contiguously on disk. When multiple streams are being ingested and played out at the same time, it is critical that the filesystem does not cross the streams and interleave them together as this creates seek and readahead cache miss latency and prevents both ingest and playout from meeting frame rate targets. This patch set creates a "stream of files" concept into the allocator to place all the data from a single stream contiguously on disk so that RAID array readahead can be used effectively. Each additional stream gets placed in different allocation groups within the filesystem, thereby ensuring that we don't cross any streams. When an AG fills up, we select a new AG for the stream that is not in use. The core of the functionality is the stream tracking - each inode that we create in a directory needs to be associated with the directories' stream. Hence every time we create a file, we look up the directories' stream object and associate the new file with that object. Once we have a stream object for a file, we use the AG that the stream object point to for allocations. If we can't allocate in that AG (e.g. it is full) we move the entire stream to another AG. Other inodes in the same stream are moved to the new AG on their next allocation (i.e. lazy update). Stream objects are kept in a cache and hold a reference on the inode. Hence the inode cannot be reclaimed while there is an outstanding stream reference. This means that on unlink we need to remove the stream association and we also need to flush all the associations on certain events that want to reclaim all unreferenced inodes (e.g. filesystem freeze). SGI-PV: 964469 SGI-Modid: xfs-linux-melb:xfs-kern:29096a Signed-off-by: David Chinner Signed-off-by: Barry Naujok Signed-off-by: Donald Douwsma Signed-off-by: Christoph Hellwig Signed-off-by: Tim Shimmin Signed-off-by: Vlad Apostolov --- fs/xfs/xfs_fs.h | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/xfs/xfs_fs.h') diff --git a/fs/xfs/xfs_fs.h b/fs/xfs/xfs_fs.h index 1b60cfc28be5..ec3c9c27e0de 100644 --- a/fs/xfs/xfs_fs.h +++ b/fs/xfs/xfs_fs.h @@ -66,6 +66,7 @@ struct fsxattr { #define XFS_XFLAG_EXTSIZE 0x00000800 /* extent size allocator hint */ #define XFS_XFLAG_EXTSZINHERIT 0x00001000 /* inherit inode extent size */ #define XFS_XFLAG_NODEFRAG 0x00002000 /* do not defragment */ +#define XFS_XFLAG_FILESTREAM 0x00004000 /* use filestream allocator */ #define XFS_XFLAG_HASATTR 0x80000000 /* no DIFLAG for this */ /* -- cgit v1.2.3-70-g09d2