X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=f323c204d3c67be97e98926ae8efd0ae1d82314d;hp=e22f745469324ea4a355c5792f88ddec2ac90ef1;hb=5f9099ea8adf423d0db01274ef0d7e65629c0e1c;hpb=b0f65863844b4de92d10fefaabde80ea5bc3e5cc

diff --git a/HOWTO b/HOWTO
index e22f7454..f323c204 100644
--- a/HOWTO
+++ b/HOWTO
@@ -314,7 +314,8 @@ filesize=int	Individual file sizes. May be a range, in which case fio
 
 fill_device=bool Sets size to something really large and waits for ENOSPC (no
 		space left on device) as the terminating condition. Only makes
-                sense with sequential write.
+                sense with sequential write. For a read workload, the mount
+		point will be filled first then IO started on the result.
 
 blocksize=int
 bs=int		The block size used for the io units. Defaults to 4k. Values
@@ -529,6 +530,9 @@ fsync=int	If writing to a file, issue a sync of the dirty data
 		not sync the file. The exception is the sg io engine, which
 		synchronizes the disk cache anyway.
 
+fsyncdata=int	Like fsync= but uses fdatasync() to only sync data and not
+		metadata blocks.
+
 overwrite=bool	If true, writes to a file will always overwrite existing
 		data. If the file doesn't already exist, it will be
 		created before the write phase begins. If the file exists
@@ -546,7 +550,9 @@ rwmixread=int	How large a percentage of the mix should be reads.
 rwmixwrite=int	How large a percentage of the mix should be writes. If both
 		rwmixread and rwmixwrite is given and the values do not add
 		up to 100%, the latter of the two will be used to override
-		the first.
+		the first. This may interfere with a given rate setting,
+		if fio is asked to limit reads or writes to a certain rate.
+		If that is the case, then the distribution may be skewed.
 
 norandommap	Normally fio will cover every block of the file when doing
 		random IO. If this option is given, fio will just get a
@@ -588,19 +594,29 @@ 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 +730,9 @@ 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
@@ -913,6 +931,14 @@ gtod_cpu=int	Sometimes it's cheaper to dedicate a single thread of
 		for doing these time calls will be excluded from other
 		uses. Fio will manually clear it from the CPU mask of other
 		jobs.
+continue_on_error=bool	Normally fio will exit the job on the first observed
+		failure. If this option is set, fio will continue the job when
+		there is a 'non-fatal error' (EIO or EILSEQ) until the runtime
+		is exceeded or the I/O size specified is completed. If this
+		option is used, there are two more stats that are appended,
+		the total error count and the first error. The error field
+		given in the stats is the first error that was hit during the
+		run.
 
 
 6.0 Interpreting the output