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Diffstat (limited to 'Documentation/admin-guide/bcache.rst')
| -rw-r--r-- | Documentation/admin-guide/bcache.rst | 18 |
1 files changed, 3 insertions, 15 deletions
diff --git a/Documentation/admin-guide/bcache.rst b/Documentation/admin-guide/bcache.rst index 8d3a2d045c0a..f71f349553e4 100644 --- a/Documentation/admin-guide/bcache.rst +++ b/Documentation/admin-guide/bcache.rst @@ -17,8 +17,7 @@ The latest bcache kernel code can be found from mainline Linux kernel: It's designed around the performance characteristics of SSDs - it only allocates in erase block sized buckets, and it uses a hybrid btree/log to track cached extents (which can be anywhere from a single sector to the bucket size). It's -designed to avoid random writes at all costs; it fills up an erase block -sequentially, then issues a discard before reusing it. +designed to avoid random writes at all costs. Both writethrough and writeback caching are supported. Writeback defaults to off, but can be switched on and off arbitrarily at runtime. Bcache goes to @@ -204,7 +203,7 @@ For example:: This should present your unmodified backing device data in /dev/loop0 If your cache is in writethrough mode, then you can safely discard the -cache device without loosing data. +cache device without losing data. E) Wiping a cache device @@ -508,9 +507,6 @@ cache_miss_collisions cache miss, but raced with a write and data was already present (usually 0 since the synchronization for cache misses was rewritten) -cache_readaheads - Count of times readahead occurred. - Sysfs - cache set ~~~~~~~~~~~~~~~~~ @@ -621,19 +617,11 @@ bucket_size cache_replacement_policy One of either lru, fifo or random. -discard - Boolean; if on a discard/TRIM will be issued to each bucket before it is - reused. Defaults to off, since SATA TRIM is an unqueued command (and thus - slow). - freelist_percent Size of the freelist as a percentage of nbuckets. Can be written to to increase the number of buckets kept on the freelist, which lets you artificially reduce the size of the cache at runtime. Mostly for testing - purposes (i.e. testing how different size caches affect your hit rate), but - since buckets are discarded when they move on to the freelist will also make - the SSD's garbage collection easier by effectively giving it more reserved - space. + purposes (i.e. testing how different size caches affect your hit rate). io_errors Number of errors that have occurred, decayed by io_error_halflife. |