blktrace fixup + documentation

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 0b438714c56cba93b9f319178231b258bb2ee47e..167ed7c7f0adb472f186bee73d8d0d364e1484f3 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -618,7 +618,12 @@ write_iolog=str    Write the issued io patterns to the specified file. See
 
 read_iolog=str Open an iolog with the specified file name and replay the
                io patterns it contains. This can be used to store a
-               workload and replay it sometime later.
+               workload and replay it sometime later. The iolog given
+               may also be a blktrace binary file, which allows fio
+               to replay a workload captured by blktrace. See blktrace
+               for how to capture such logging data. For blktrace replay,
+               the file needs to be turned into a blkparse binary data
+               file first (blktrace <device> -d file_for_fio.bin).
 
 write_bw_log   If given, write a bandwidth log of the jobs in this job
                file. Can be used to store data of the bandwidth of the