1 What: /sys/block/<disk>/bcache/unregister 2 Date: November 2010 3 Contact: Kent Overstreet <kent.overstreet@gmail.com> 4 Description: 5 A write to this file causes the backing device or cache to be 6 unregistered. If a backing device had dirty data in the cache, 7 writeback mode is automatically disabled and all dirty data is 8 flushed before the device is unregistered. Caches unregister 9 all associated backing devices before unregistering themselves. 10 11 What: /sys/block/<disk>/bcache/clear_stats 12 Date: November 2010 13 Contact: Kent Overstreet <kent.overstreet@gmail.com> 14 Description: 15 Writing to this file resets all the statistics for the device. 16 17 What: /sys/block/<disk>/bcache/cache 18 Date: November 2010 19 Contact: Kent Overstreet <kent.overstreet@gmail.com> 20 Description: 21 For a backing device that has cache, a symlink to 22 the bcache/ dir of that cache. 23 24 What: /sys/block/<disk>/bcache/cache_hits 25 Date: November 2010 26 Contact: Kent Overstreet <kent.overstreet@gmail.com> 27 Description: 28 For backing devices: integer number of full cache hits, 29 counted per bio. A partial cache hit counts as a miss. 30 31 What: /sys/block/<disk>/bcache/cache_misses 32 Date: November 2010 33 Contact: Kent Overstreet <kent.overstreet@gmail.com> 34 Description: 35 For backing devices: integer number of cache misses. 36 37 What: /sys/block/<disk>/bcache/cache_hit_ratio 38 Date: November 2010 39 Contact: Kent Overstreet <kent.overstreet@gmail.com> 40 Description: 41 For backing devices: cache hits as a percentage. 42 43 What: /sys/block/<disk>/bcache/sequential_cutoff 44 Date: November 2010 45 Contact: Kent Overstreet <kent.overstreet@gmail.com> 46 Description: 47 For backing devices: Threshold past which sequential IO will 48 skip the cache. Read and written as bytes in human readable 49 units (i.e. echo 10M > sequntial_cutoff). 50 51 What: /sys/block/<disk>/bcache/bypassed 52 Date: November 2010 53 Contact: Kent Overstreet <kent.overstreet@gmail.com> 54 Description: 55 Sum of all reads and writes that have bypassed the cache (due 56 to the sequential cutoff). Expressed as bytes in human 57 readable units. 58 59 What: /sys/block/<disk>/bcache/writeback 60 Date: November 2010 61 Contact: Kent Overstreet <kent.overstreet@gmail.com> 62 Description: 63 For backing devices: When on, writeback caching is enabled and 64 writes will be buffered in the cache. When off, caching is in 65 writethrough mode; reads and writes will be added to the 66 cache but no write buffering will take place. 67 68 What: /sys/block/<disk>/bcache/writeback_running 69 Date: November 2010 70 Contact: Kent Overstreet <kent.overstreet@gmail.com> 71 Description: 72 For backing devices: when off, dirty data will not be written 73 from the cache to the backing device. The cache will still be 74 used to buffer writes until it is mostly full, at which point 75 writes transparently revert to writethrough mode. Intended only 76 for benchmarking/testing. 77 78 What: /sys/block/<disk>/bcache/writeback_delay 79 Date: November 2010 80 Contact: Kent Overstreet <kent.overstreet@gmail.com> 81 Description: 82 For backing devices: In writeback mode, when dirty data is 83 written to the cache and the cache held no dirty data for that 84 backing device, writeback from cache to backing device starts 85 after this delay, expressed as an integer number of seconds. 86 87 What: /sys/block/<disk>/bcache/writeback_percent 88 Date: November 2010 89 Contact: Kent Overstreet <kent.overstreet@gmail.com> 90 Description: 91 For backing devices: If nonzero, writeback from cache to 92 backing device only takes place when more than this percentage 93 of the cache is used, allowing more write coalescing to take 94 place and reducing total number of writes sent to the backing 95 device. Integer between 0 and 40. 96 97 What: /sys/block/<disk>/bcache/synchronous 98 Date: November 2010 99 Contact: Kent Overstreet <kent.overstreet@gmail.com> 100 Description: 101 For a cache, a boolean that allows synchronous mode to be 102 switched on and off. In synchronous mode all writes are ordered 103 such that the cache can reliably recover from unclean shutdown; 104 if disabled bcache will not generally wait for writes to 105 complete but if the cache is not shut down cleanly all data 106 will be discarded from the cache. Should not be turned off with 107 writeback caching enabled. 108 109 What: /sys/block/<disk>/bcache/discard 110 Date: November 2010 111 Contact: Kent Overstreet <kent.overstreet@gmail.com> 112 Description: 113 For a cache, a boolean allowing discard/TRIM to be turned off 114 or back on if the device supports it. 115 116 What: /sys/block/<disk>/bcache/bucket_size 117 Date: November 2010 118 Contact: Kent Overstreet <kent.overstreet@gmail.com> 119 Description: 120 For a cache, bucket size in human readable units, as set at 121 cache creation time; should match the erase block size of the 122 SSD for optimal performance. 123 124 What: /sys/block/<disk>/bcache/nbuckets 125 Date: November 2010 126 Contact: Kent Overstreet <kent.overstreet@gmail.com> 127 Description: 128 For a cache, the number of usable buckets. 129 130 What: /sys/block/<disk>/bcache/tree_depth 131 Date: November 2010 132 Contact: Kent Overstreet <kent.overstreet@gmail.com> 133 Description: 134 For a cache, height of the btree excluding leaf nodes (i.e. a 135 one node tree will have a depth of 0). 136 137 What: /sys/block/<disk>/bcache/btree_cache_size 138 Date: November 2010 139 Contact: Kent Overstreet <kent.overstreet@gmail.com> 140 Description: 141 Number of btree buckets/nodes that are currently cached in 142 memory; cache dynamically grows and shrinks in response to 143 memory pressure from the rest of the system. 144 145 What: /sys/block/<disk>/bcache/written 146 Date: November 2010 147 Contact: Kent Overstreet <kent.overstreet@gmail.com> 148 Description: 149 For a cache, total amount of data in human readable units 150 written to the cache, excluding all metadata. 151 152 What: /sys/block/<disk>/bcache/btree_written 153 Date: November 2010 154 Contact: Kent Overstreet <kent.overstreet@gmail.com> 155 Description: 156 For a cache, sum of all btree writes in human readable units.
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