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kernel/linux-imx6_3.14.28/Documentation/ABI/testing/sysfs-block-bcache 5.74 KB
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  What:		/sys/block/<disk>/bcache/unregister
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		A write to this file causes the backing device or cache to be
  		unregistered. If a backing device had dirty data in the cache,
  		writeback mode is automatically disabled and all dirty data is
  		flushed before the device is unregistered. Caches unregister
  		all associated backing devices before unregistering themselves.
  
  What:		/sys/block/<disk>/bcache/clear_stats
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		Writing to this file resets all the statistics for the device.
  
  What:		/sys/block/<disk>/bcache/cache
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For a backing device that has cache, a symlink to
  		the bcache/ dir of that cache.
  
  What:		/sys/block/<disk>/bcache/cache_hits
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For backing devices: integer number of full cache hits,
  		counted per bio. A partial cache hit counts as a miss.
  
  What:		/sys/block/<disk>/bcache/cache_misses
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For backing devices: integer number of cache misses.
  
  What:		/sys/block/<disk>/bcache/cache_hit_ratio
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For backing devices: cache hits as a percentage.
  
  What:		/sys/block/<disk>/bcache/sequential_cutoff
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For backing devices: Threshold past which sequential IO will
  		skip the cache. Read and written as bytes in human readable
  		units (i.e. echo 10M > sequntial_cutoff).
  
  What:		/sys/block/<disk>/bcache/bypassed
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		Sum of all reads and writes that have bypassed the cache (due
  		to the sequential cutoff).  Expressed as bytes in human
  		readable units.
  
  What:		/sys/block/<disk>/bcache/writeback
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For backing devices: When on, writeback caching is enabled and
  		writes will be buffered in the cache. When off, caching is in
  		writethrough mode; reads and writes will be added to the
  		cache but no write buffering will take place.
  
  What:		/sys/block/<disk>/bcache/writeback_running
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For backing devices: when off, dirty data will not be written
  		from the cache to the backing device. The cache will still be
  		used to buffer writes until it is mostly full, at which point
  		writes transparently revert to writethrough mode. Intended only
  		for benchmarking/testing.
  
  What:		/sys/block/<disk>/bcache/writeback_delay
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For backing devices: In writeback mode, when dirty data is
  		written to the cache and the cache held no dirty data for that
  		backing device, writeback from cache to backing device starts
  		after this delay, expressed as an integer number of seconds.
  
  What:		/sys/block/<disk>/bcache/writeback_percent
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For backing devices: If nonzero, writeback from cache to
  		backing device only takes place when more than this percentage
  		of the cache is used, allowing more write coalescing to take
  		place and reducing total number of writes sent to the backing
  		device. Integer between 0 and 40.
  
  What:		/sys/block/<disk>/bcache/synchronous
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For a cache, a boolean that allows synchronous mode to be
  		switched on and off. In synchronous mode all writes are ordered
  		such that the cache can reliably recover from unclean shutdown;
  		if disabled bcache will not generally wait for writes to
  		complete but if the cache is not shut down cleanly all data
  		will be discarded from the cache. Should not be turned off with
  		writeback caching enabled.
  
  What:		/sys/block/<disk>/bcache/discard
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For a cache, a boolean allowing discard/TRIM to be turned off
  		or back on if the device supports it.
  
  What:		/sys/block/<disk>/bcache/bucket_size
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For a cache, bucket size in human readable units, as set at
  		cache creation time; should match the erase block size of the
  		SSD for optimal performance.
  
  What:		/sys/block/<disk>/bcache/nbuckets
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For a cache, the number of usable buckets.
  
  What:		/sys/block/<disk>/bcache/tree_depth
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For a cache, height of the btree excluding leaf nodes (i.e. a
  		one node tree will have a depth of 0).
  
  What:		/sys/block/<disk>/bcache/btree_cache_size
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		Number of btree buckets/nodes that are currently cached in
  		memory; cache dynamically grows and shrinks in response to
  		memory pressure from the rest of the system.
  
  What:		/sys/block/<disk>/bcache/written
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For a cache, total amount of data in human readable units
  		written to the cache, excluding all metadata.
  
  What:		/sys/block/<disk>/bcache/btree_written
  Date:		November 2010
  Contact:	Kent Overstreet <kent.overstreet@gmail.com>
  Description:
  		For a cache, sum of all btree writes in human readable units.