Add information about bloom filter to config.md

License: MIT Signed-off-by: Dominic Della Valle <ddvpublic@gmail.com>
ipfs · Apr 8, 2018 · bdedec2 · bdedec2
1 parent 18eb6e8
commit bdedec2
Showing 1 changed file with 6 additions and 2 deletions.
diff --git a/docs/config.md b/docs/config.md
@@ -141,8 +141,12 @@ A boolean value. If set to true, all block reads from disk will be hashed and
 verified. This will cause increased CPU utilization.
 
 - `BloomFilterSize`
-A number representing the size in bytes of the blockstore's bloom filter. A
-value of zero represents the feature being disabled.
+A number representing the size in bytes of the blockstore's [bloom filter](https://en.wikipedia.org/wiki/Bloom_filter). A value of zero represents the feature being disabled.  
+
+This site generates useful graphs for various bloom filter values: <https://hur.st/bloomfilter/?n=1e6&p=0.01&m=&k=7>
+You may use it to find a preferred optimal value, where 'm' is BloomFilterSize.
+For example, for 1,000,000 blocks, expecting a 1% false positive rate, you'd end up with a filter size of 9592955 bytes. [Currently](https://github.com/ipfs/go-ipfs/blob/9c194aa7e2febeab0cbd895067d7d90d82b137f9/blocks/blockstore/caching.go), 7 hash functions are used by default, so the constant k is 7.
+
 
 Default: `0`