bcache: clarify free/available/unused space
Don't describe bcache_available_percent as free space but as
non-writeback space. Describe priority_stats in more detail
and point to that for total bcache occupation.
Signed-off-by: Gabriel de Perthuis <g2p.code+bcache@gmail.com>
Signed-off-by: Kent Overstreet <koverstreet@google.com>
diff --git a/Documentation/bcache.txt b/Documentation/bcache.txt
index 77db880..b3a7e7d 100644
--- a/Documentation/bcache.txt
+++ b/Documentation/bcache.txt
@@ -319,7 +319,10 @@
Symlink to each of the cache devices comprising this cache set.
cache_available_percent
- Percentage of cache device free.
+ Percentage of cache device which doesn't contain dirty data, and could
+ potentially be used for writeback. This doesn't mean this space isn't used
+ for clean cached data; the unused statistic (in priority_stats) is typically
+ much lower.
clear_stats
Clears the statistics associated with this cache
@@ -423,8 +426,11 @@
Total buckets in this cache
priority_stats
- Statistics about how recently data in the cache has been accessed. This can
- reveal your working set size.
+ Statistics about how recently data in the cache has been accessed.
+ This can reveal your working set size. Unused is the percentage of
+ the cache that doesn't contain any data. Metadata is bcache's
+ metadata overhead. Average is the average priority of cache buckets.
+ Next is a list of quantiles with the priority threshold of each.
written
Sum of all data that has been written to the cache; comparison with