X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=0085b7471ff669119b669495b591a3053ff10c32;hp=a7d6db4d84b6489380f2aff41f3ff6d8fc6b49a8;hb=3c746856fd63f3f7624a34ea70e226a290d9cc01;hpb=769d13b5c5c4948c89311b55bce26cec4196e3d1

diff --git a/HOWTO b/HOWTO
index a7d6db4d..0085b747 100644
--- a/HOWTO
+++ b/HOWTO
@@ -1606,10 +1606,18 @@ write_lat_log=str Same as write_bw_log, except that this option stores io
 		The actual log names will be foo_slat.x.log, foo_clat.x.log,
 		and foo_lat.x.log, where x is the index of the job (1..N,
 		where N is the number of jobs). This helps fio_generate_plot
-		fine the logs automatically. If 'per_job_logs' is false, then
+		find the logs automatically. If 'per_job_logs' is false, then
 		the filename will not include the job index. See 'Log File
 		Formats'.
 
+write_hist_log=str Same as write_lat_log, but writes I/O completion
+		latency histograms. If no filename is given with this option, the
+		default filename of "jobname_clat_hist.x.log" is used, where x is
+		the index of the job (1..N, where N is the number of jobs). Even
+		if the filename is given, fio will still append the type of log.
+		If per_job_logs is false, then the filename will not include the
+		job index. See 'Log File Formats'.
+
 write_iops_log=str Same as write_bw_log, but writes IOPS. If no filename is
 		given with this option, the default filename of
 		"jobname_type.x.log" is used,where x is the index of the job
@@ -1625,6 +1633,20 @@ log_avg_msec=int By default, fio will log an entry in the iops, latency,
 		specified period of time, reducing the resolution of the log.
 		See log_max_value as well. Defaults to 0, logging all entries.
 
+log_hist_msec=int Same as log_avg_msec, but logs entries for completion
+		latency histograms. Computing latency percentiles from averages of
+		intervals using log_avg_msec 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 log_hist_coarseness as well. Defaults to 0, meaning histogram
+		logging is disabled.
+
+log_hist_coarseness=int Integer ranging from 0 to 6, defining the coarseness
+		of the resolution of the histogram logs enabled with log_hist_msec. For
+		each increment in coarseness, fio outputs half as many bins. Defaults to
+		0, for which histogram logs contain 1216 latency bins. See
+		'Log File Formats'.
+
 log_max_value=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