options: full control of fadvise hinting

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 6893c86878b2d9420bf263eb5e04056440cd322d..7274c0e940af1c3850e33c5a84092702dff56c13 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -476,8 +476,17 @@ fadvise_hint=bool By default, fio will use fadvise() to advise the kernel
                on what IO patterns it is likely to issue. Sometimes you
                want to test specific IO patterns without telling the
                kernel about it, in which case you can disable this option.
-               If set, fio will use POSIX_FADV_SEQUENTIAL for sequential
-               IO and POSIX_FADV_RANDOM for random IO.
+               The following options are supported:
+
+                       sequential      Use FADV_SEQUENTIAL
+                       random          Use FADV_RANDOM
+                       1               Backwards-compatible hint for basing
+                                       the hint on the fio workload. Will use
+                                       FADV_SEQUENTIAL for a sequential
+                                       workload, and FADV_RANDOM for a random
+                                       workload.
+                       0               Backwards-compatible setting for not
+                                       issing a fadvise hint.
 
 fadvise_stream=int Notify the kernel what write stream ID to place these
                writes under. Only supported on Linux. Note, this option