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Based on kernel version 3.13. Page generated on 2014-01-20 21:59 EST.

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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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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