parse: make suggestions for unknown options

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index c73b9ecdc859a8912718968918fe837543a258b7..57d3fb7f1e4de2484e071d428eab3f66de1038c4 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -594,9 +594,12 @@ scramble_buffers=bool      If refill_buffers is too costly and the target is
 buffer_compress_percentage=int If this is set, then fio will attempt to
                provide IO buffer content (on WRITEs) that compress to
                the specified level. Fio does this by providing a mix of
-               random data and zeroes. Note that this is per block size
-               unit, for file/disk wide compression level that matches
-               this setting, you'll also want to set refill_buffers.
+               random data and a fixed pattern. The fixed pattern is either
+               zeroes, or the pattern specified by buffer_pattern. If the
+               pattern option is used, it might skew the compression ratio
+               slightly. Note that this is per block size unit, for file/disk
+               wide compression level that matches this setting, you'll also
+               want to set refill_buffers.
 
 buffer_compress_chunk=int      See buffer_compress_percentage. This
                setting allows fio to manage how big the ranges of random