+.BI log_hist_msec \fR=\fPint
+Same as \fBlog_avg_msec\fR, but logs entries for completion latency histograms.
+Computing latency percentiles from averages of intervals using \fBlog_avg_msec\fR
+is innacurate. Setting this option makes fio log histogram entries over the
+specified period of time, reducing log sizes for high IOPS devices while
+retaining percentile accuracy. See \fBlog_hist_coarseness\fR as well. Defaults
+to 0, meaning histogram logging is disabled.
+.TP
+.BI log_hist_coarseness \fR=\fPint
+Integer ranging from 0 to 6, defining the coarseness of the resolution of the
+histogram logs enabled with \fBlog_hist_msec\fR. For each increment in
+coarseness, fio outputs half as many bins. Defaults to 0, for which histogram
+logs contain 1216 latency bins. See the \fBLOG FILE FORMATS\fR section.
+.TP