mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-31 08:28:13 +00:00
cafe563591
Does writethrough and writeback caching, handles unclean shutdown, and has a bunch of other nifty features motivated by real world usage. See the wiki at http://bcache.evilpiepirate.org for more. Signed-off-by: Kent Overstreet <koverstreet@google.com>
156 lines
5.7 KiB
Text
156 lines
5.7 KiB
Text
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.
|