drivers/md/dm-vdo/constants.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright 2023 Red Hat
   4  */
   5
   6 #ifndef VDO_CONSTANTS_H
   7 #define VDO_CONSTANTS_H
   8
   9 #include <linux/blkdev.h>
  10
  11 #include "types.h"
  12
  13 enum {
  14         /*
  15          * The maximum number of contiguous PBNs which will go to a single bio submission queue,
  16          * assuming there is more than one queue.
  17          */
  18         VDO_BIO_ROTATION_INTERVAL_LIMIT = 1024,
  19
  20         /* The number of entries on a block map page */
  21         VDO_BLOCK_MAP_ENTRIES_PER_PAGE = 812,
  22
  23         /* The origin of the flat portion of the block map */
  24         VDO_BLOCK_MAP_FLAT_PAGE_ORIGIN = 1,
  25
  26         /*
  27          * The height of a block map tree. Assuming a root count of 60 and 812 entries per page,
  28          * this is big enough to represent almost 95 PB of logical space.
  29          */
  30         VDO_BLOCK_MAP_TREE_HEIGHT = 5,
  31
  32         /* The default number of bio submission queues. */
  33         DEFAULT_VDO_BIO_SUBMIT_QUEUE_COUNT = 4,
  34
  35         /* The number of contiguous PBNs to be submitted to a single bio queue. */
  36         DEFAULT_VDO_BIO_SUBMIT_QUEUE_ROTATE_INTERVAL = 64,
  37
  38         /* The number of trees in the arboreal block map */
  39         DEFAULT_VDO_BLOCK_MAP_TREE_ROOT_COUNT = 60,
  40
  41         /* The default size of the recovery journal, in blocks */
  42         DEFAULT_VDO_RECOVERY_JOURNAL_SIZE = 32 * 1024,
  43
  44         /* The default size of each slab journal, in blocks */
  45         DEFAULT_VDO_SLAB_JOURNAL_SIZE = 224,
  46
  47         /* Unit test minimum */
  48         MINIMUM_VDO_SLAB_JOURNAL_BLOCKS = 2,
  49
  50         /*
  51          * The initial size of lbn_operations and pbn_operations, which is based upon the expected
  52          * maximum number of outstanding VIOs. This value was chosen to make it highly unlikely
  53          * that the maps would need to be resized.
  54          */
  55         VDO_LOCK_MAP_CAPACITY = 10000,
  56
  57         /* The maximum number of logical zones */
  58         MAX_VDO_LOGICAL_ZONES = 60,
  59
  60         /* The maximum number of physical zones */
  61         MAX_VDO_PHYSICAL_ZONES = 16,
  62
  63         /* The base-2 logarithm of the maximum blocks in one slab */
  64         MAX_VDO_SLAB_BITS = 23,
  65
  66         /* The maximum number of slabs the slab depot supports */
  67         MAX_VDO_SLABS = 8192,
  68
  69         /*
  70          * The maximum number of block map pages to load simultaneously during recovery or rebuild.
  71          */
  72         MAXIMUM_SIMULTANEOUS_VDO_BLOCK_MAP_RESTORATION_READS = 1024,
  73
  74         /* The maximum number of entries in the slab summary */
  75         MAXIMUM_VDO_SLAB_SUMMARY_ENTRIES = MAX_VDO_SLABS * MAX_VDO_PHYSICAL_ZONES,
  76
  77         /* The maximum number of total threads in a VDO thread configuration. */
  78         MAXIMUM_VDO_THREADS = 100,
  79
  80         /* The maximum number of VIOs in the system at once */
  81         MAXIMUM_VDO_USER_VIOS = 2048,
  82
  83         /* The only physical block size supported by VDO */
  84         VDO_BLOCK_SIZE = 4096,
  85
  86         /* The number of sectors per block */
  87         VDO_SECTORS_PER_BLOCK = (VDO_BLOCK_SIZE >> SECTOR_SHIFT),
  88
  89         /* The size of a sector that will not be torn */
  90         VDO_SECTOR_SIZE = 512,
  91
  92         /* The physical block number reserved for storing the zero block */
  93         VDO_ZERO_BLOCK = 0,
  94 };
  95
  96 #endif /* VDO_CONSTANTS_H */