+/*
+ * The following constants set the defaults used for the number
+ * of sectors (fs_nsect), and number of tracks (fs_ntrak).
+ */
+#define DFLNSECT 32
+#define DFLNTRAK 16
+
+/*
+ * The following two constants set the default block and fragment sizes.
+ * Both constants must be a power of 2 and meet the following constraints:
+ * MINBSIZE <= DESBLKSIZE <= MAXBSIZE
+ * DEV_BSIZE <= DESFRAGSIZE <= DESBLKSIZE
+ * DESBLKSIZE / DESFRAGSIZE <= 8
+ */
+#define DESBLKSIZE 8192
+#define DESFRAGSIZE 1024
+
+/*
+ * Cylinder groups may have up to MAXCPG cylinders. The actual
+ * number used depends upon how much information can be stored
+ * on a single cylinder. The default is to used 16 cylinders
+ * per group.
+ */
+#define DESCPG 16 /* desired fs_cpg */
+
+/*
+ * MINFREE gives the minimum acceptable percentage of file system
+ * blocks which may be free. If the freelist drops below this level
+ * only the superuser may continue to allocate blocks. This may
+ * be set to 0 if no reserve of free blocks is deemed necessary,
+ * however throughput drops by fifty percent if the file system
+ * is run at between 90% and 100% full; thus the default value of
+ * fs_minfree is 10%.
+ */
+#define MINFREE 10
+
+/*
+ * ROTDELAY gives the minimum number of milliseconds to initiate
+ * another disk transfer on the same cylinder. It is used in
+ * determining the rotationally optimal layout for disk blocks
+ * within a file; the default of fs_rotdelay is 2ms.
+ */
+#define ROTDELAY 2
+
+/*
+ * MAXCONTIG sets the default for the maximum number of blocks
+ * that may be allocated sequentially. Since UNIX drivers are
+ * not capable of scheduling multi-block transfers, this defaults
+ * to 1 (ie no contiguous blocks are allocated).
+ */
+#define MAXCONTIG 1
+
+/*
+ * MAXBLKPG determines the maximum number of data blocks which are
+ * placed in a single cylinder group. This is currently a function
+ * of the block and fragment size of the file system.
+ */
+#define MAXBLKPG(fs) ((fs)->fs_fsize / sizeof(daddr_t))
+
+/*
+ * Each file system has a number of inodes statically allocated.
+ * We allocate one inode slot per NBPI bytes, expecting this
+ * to be far more than we will ever need.
+ */
+#define NBPI 2048
+
projects / unix-history / blobdiff