From fe0a797a6b42d9ad0ed063eaef705da1eb3c8147 Mon Sep 17 00:00:00 2001
From: Gabriel <g2p.code+bcache@gmail.com>
Date: Wed, 24 Apr 2013 19:51:02 +0200
Subject: 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>
---
 Documentation/bcache.txt | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

(limited to 'Documentation')

diff --git a/Documentation/bcache.txt b/Documentation/bcache.txt
index 77db8809bd96..b3a7e7d384f6 100644
--- a/Documentation/bcache.txt
+++ b/Documentation/bcache.txt
@@ -319,7 +319,10 @@ cache<0..n>
   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 @@ nbuckets
   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
-- 
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