log: add support for logging max instead of averages

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 7c24c1b74296aa33cdff97eca9458defd291b6ca..6d80360574e0c89899756cbc6a1d9838293c9c81 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -1013,7 +1013,9 @@ random_generator=str      Fio supports the following engines for generating
                typically good enough. LFSR only works with single
                block sizes, not with workloads that use multiple block
                sizes. If used with such a workload, fio may read or write
-               some blocks multiple times.
+               some blocks multiple times. The default value is tausworthe,
+               unless the required space exceeds 2^32 blocks. If it does,
+               then tausworthe64 is selected automatically.
 
 nice=int       Run the job with the given nice value. See man nice(2).
 
@@ -1568,8 +1570,12 @@ log_avg_msec=int By default, fio will log an entry in the iops, latency,
                disk log, that can quickly grow to a very large size. Setting
                this option makes fio average the each log entry over the
                specified period of time, reducing the resolution of the log.
-               Defaults to 0.
+               See log_max as well. Defaults to 0, logging all entries.
 
+log_max=bool   If log_avg_msec is set, fio logs the average over that window.
+               If you instead want to log the maximum value, set this option
+               to 1. Defaults to 0, meaning that averaged values are logged.
+.
 log_offset=int If this is set, the iolog options will include the byte
                offset for the IO entry as well as the other data values.