Yeah, I'm not suprised by those comments :) Been trying to work out how to
"describe" them better...
On Thu, 04 Sep 2008 09:47:58 +1000, Christoph Hellwig <hch@xxxxxxxxxxxxx>
wrote:
cache_node_set_priority(libxfs_bcache, (struct cache_node *)bp,
- cache_node_get_priority((struct cache_node *)bp) - 4);
+ cache_node_get_priority((struct cache_node *)bp) - 8);
???
#define B_DIR_BMAP 15
-#define B_DIR_META_2 13 /* metadata in secondary queue */
-#define B_DIR_META_H 11 /* metadata fetched for PF_META_ONLY */
-#define B_DIR_META_S 9 /* single block of metadata */
-#define B_DIR_META 7
-#define B_DIR_INODE 6
-#define B_BMAP 5
-#define B_INODE 4
+#define B_DIR_META_2 14 /* metadata in secondary queue */
+#define B_DIR_META_H 13 /* metadata fetched for PF_META_ONLY */
+#define B_DIR_META_S 12 /* single block of metadata */
+#define B_DIR_META 11
+#define B_DIR_INODE 10
+#define B_BMAP 9
+#define B_INODE 8
Changing priorities, this could use some explanation in the
patch description..
-#define B_IS_INODE(b) (((b) & 1) == 0)
-#define B_IS_META(b) (((b) & 1) != 0)
+#define B_IS_INODE(f) (((f) & 5) == 0)
+#define B_IS_META(f) (((f) & 5) != 0)
And these two macros really want some comments describing them.
How's this snippet of the patch then?
Index: xfs-cmds/xfsprogs/include/cache.h
===================================================================
--- xfs-cmds.orig/xfsprogs/include/cache.h
+++ xfs-cmds/xfsprogs/include/cache.h
@@ -20,6 +20,17 @@
#define HASH_CACHE_RATIO 8
+/*
+ * Cache priorities range from BASE to MAX.
+ *
+ * For prefetch support, the top half of the range starts at
+ * CACHE_PREFETCH_PRIORITY and everytime the buffer is fetched
+ * and is at or above this priority level, it is reduced to
+ * below this level (refer to libxfs_getbuf).
+ */
+
+#define CACHE_BASE_PRIORITY 0
+#define CACHE_PREFETCH_PRIORITY 8
#define CACHE_MAX_PRIORITY 15
/*
Index: xfs-cmds/xfsprogs/libxfs/rdwr.c
===================================================================
--- xfs-cmds.orig/xfsprogs/libxfs/rdwr.c
+++ xfs-cmds/xfsprogs/libxfs/rdwr.c
@@ -393,7 +393,8 @@ libxfs_getbuf(dev_t device, xfs_daddr_t
if (use_xfs_buf_lock)
pthread_mutex_lock(&bp->b_lock);
cache_node_set_priority(libxfs_bcache, (struct cache_node *)bp,
- cache_node_get_priority((struct cache_node *)bp) - 4);
+ cache_node_get_priority((struct cache_node *)bp) -
+ CACHE_PREFETCH_PRIORITY);
#ifdef XFS_BUF_TRACING
pthread_mutex_lock(&libxfs_bcache->c_mutex);
lock_buf_count++;
Index: xfs-cmds/xfsprogs/repair/prefetch.c
===================================================================
--- xfs-cmds.orig/xfsprogs/repair/prefetch.c
+++ xfs-cmds/xfsprogs/repair/prefetch.c
@@ -35,19 +35,36 @@ static int pf_batch_fsbs;
static void pf_read_inode_dirs(prefetch_args_t *, xfs_buf_t *);
-/* buffer priorities for the libxfs cache */
+/*
+ * Buffer priorities for the libxfs cache
+ *
+ * Directory metadata is ranked higher than other metadata as it's used
+ * in phases 3, 4 and 6, while other metadata is only used in 3 & 4.
+ */
-#define B_DIR_BMAP 15
-#define B_DIR_META_2 13 /* metadata in secondary queue */
-#define B_DIR_META_H 11 /* metadata fetched for PF_META_ONLY */
-#define B_DIR_META_S 9 /* single block of metadata */
-#define B_DIR_META 7
-#define B_DIR_INODE 6
-#define B_BMAP 5
-#define B_INODE 4
+/* intermediate directory btree nodes - can't be queued */
+#define B_DIR_BMAP CACHE_PREFETCH_PRIORITY + 7
+/* directory metadata in secondary queue */
+#define B_DIR_META_2 CACHE_PREFETCH_PRIORITY + 6
+/* dir metadata that had to fetched from the primary queue to avoid
stalling */
+#define B_DIR_META_H CACHE_PREFETCH_PRIORITY + 5
+/* single block of directory metadata (can't batch read) */
+#define B_DIR_META_S CACHE_PREFETCH_PRIORITY + 4
+/* dir metadata with more than one block fetched in a single I/O */
+#define B_DIR_META CACHE_PREFETCH_PRIORITY + 3
+/* inode clusters with directory inodes */
+#define B_DIR_INODE CACHE_PREFETCH_PRIORITY + 2
+/* intermediate extent btree nodes */
+#define B_BMAP CACHE_PREFETCH_PRIORITY + 1
+/* inode clusters without any directory entries */
+#define B_INODE CACHE_PREFETCH_PRIORITY
-#define B_IS_INODE(b) (((b) & 1) == 0)
-#define B_IS_META(b) (((b) & 1) != 0)
+/*
+ * Test if bit 0 or 2 is set in the "priority tag" of the buffer to see if
+ * the buffer is for an inode or other metadata.
+ */
+#define B_IS_INODE(f) (((f) & 5) == 0)
+#define B_IS_META(f) (((f) & 5) != 0)
#define DEF_BATCH_BYTES 0x10000
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