X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=8f7320835c914ea54820a4b35330a8cb2d06205d;hp=e22f745469324ea4a355c5792f88ddec2ac90ef1;hb=581e71417760e0aa86eac0acd704253ff0eeea4f;hpb=b0f65863844b4de92d10fefaabde80ea5bc3e5cc

diff --git a/HOWTO b/HOWTO
index e22f7454..8f732083 100644
--- a/HOWTO
+++ b/HOWTO
@@ -588,19 +588,29 @@ thinktime_blocks
 		defaults to 1 which will make fio wait 'thinktime' usecs
 		after every block.
 
-rate=int	Cap the bandwidth used by this job to this number of KiB/sec.
+rate=int	Cap the bandwidth used by this job. The number is in bytes/sec,
+		the normal postfix rules apply. You can use rate=500k to limit
+		reads and writes to 500k each, or you can specify read and
+		writes separately. Using rate=1m,500k would limit reads to
+		1MB/sec and writes to 500KB/sec. Capping only reads or
+		writes can be done with rate=,500k or rate=500k,. The former
+		will only limit writes (to 500KB/sec), the latter will only
+		limit reads.
 
 ratemin=int	Tell fio to do whatever it can to maintain at least this
 		bandwidth. Failing to meet this requirement, will cause
-		the job to exit.
+		the job to exit. The same format as rate is used for
+		read vs write separation.
 
 rate_iops=int	Cap the bandwidth to this number of IOPS. Basically the same
 		as rate, just specified independently of bandwidth. If the
 		job is given a block size range instead of a fixed value,
-		the smallest block size is used as the metric.
+		the smallest block size is used as the metric. The same format
+		as rate is used for read vs write seperation.
 
 rate_iops_min=int If fio doesn't meet this rate of IO, it will cause
-		the job to exit.
+		the job to exit. The same format as rate is used for read vs
+		write seperation.
 
 ratecycle=int	Average bandwidth for 'rate' and 'ratemin' over this number
 		of milliseconds.
@@ -714,7 +724,9 @@ create_on_open=bool	Don't pre-setup the files for IO, just create open()
 			when it's time to do IO to that file.
 
 pre_read=bool	If this is given, files will be pre-read into memory before
-		starting the given IO operation.
+		starting the given IO operation. This will also clear
+		the 'invalidate' flag, since it is pointless to pre-read
+		and then drop the cache.
 
 unlink=bool	Unlink the job files when done. Not the default, as repeated
 		runs of that job would then waste time recreating the file