Add option for specifically setting buffer contents

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index ac6e258f06ed86f40e18f77cd9931534add7a610..c3672d85d361638e532434a758b05f31a429a424 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -384,6 +384,11 @@ unified_rw_reporting=bool  Fio normally reports statistics on a per
 randrepeat=bool        For random IO workloads, seed the generator in a predictable
                way so that results are repeatable across repetitions.
 
+randseed=int   Seed the random number generators based on this seed value, to
+               be able to control what sequence of output is being generated.
+               If not set, the random sequence depends on the randrepeat
+               setting.
+
 use_os_rand=bool Fio can either use the random generator supplied by the OS
                to generator random offsets, or it can use it's own internal
                generator (based on Tausworthe). Default is to use the
@@ -542,6 +547,11 @@ buffer_compress_chunk=int  See buffer_compress_percentage. This
                alternate random and zeroed data throughout the IO
                buffer.
 
+buffer_pattern=str     If set, fio will fill the io buffers with this pattern.
+               If not set, the contents of io buffers is defined by the other
+               options related to buffer contents. The setting can be any
+               pattern of bytes, and can be prefixed with 0x for hex values.
+
 nrfiles=int    Number of files to use for this job. Defaults to 1.
 
 openfiles=int  Number of files to keep open at the same time. Defaults to
@@ -695,6 +705,11 @@ direct=bool        If value is true, use non-buffered io. This is usually
                O_DIRECT. Note that ZFS on Solaris doesn't support direct io.
                On Windows the synchronous ioengines don't support direct io.
 
+atomic=bool    If value is true, attempt to use atomic direct IO. Atomic
+               writes are guaranteed to be stable once acknowledged by
+               the operating system. Only Linux supports O_ATOMIC right
+               now.
+
 buffered=bool  If value is true, use buffered io. This is the opposite
                of the 'direct' option. Defaults to true.
 
@@ -876,6 +891,20 @@ rate_iops_min=int If fio doesn't meet this rate of IO, it will cause
                the job to exit. The same format as rate is used for read vs
                write separation.
 
+latency_target=int     If set, fio will attempt to find the max performance
+               point that the given workload will run at while maintaining a
+               latency below this target. The values is given in microseconds.
+               See latency_window and latency_percentile
+
+latency_window=int     Used with latency_target to specify the sample window
+               that the job is run at varying queue depths to test the
+               performance. The value is given in microseconds.
+
+latency_percentile=float       The percentage of IOs that must fall within the
+               criteria specified by latency_target and latency_window. If not
+               set, this defaults to 100.0, meaning that all IOs must be equal
+               or below to the value set by latency_target.
+
 max_latency=int        If set, fio will exit the job if it exceeds this maximum
                latency. It will exit with an ETIME error.
 
@@ -1151,9 +1180,6 @@ verify_backlog=int        Fio will normally verify the written contents of a
                holding this meta data. If this option is enabled, fio
                will write only N blocks before verifying these blocks.
 
-               will verify the previously written blocks before continuing
-               to write new ones.
-
 verify_backlog_batch=int       Control how many blocks fio will verify
                if verify_backlog is set. If not set, will default to
                the value of verify_backlog (meaning the entire queue
@@ -1252,9 +1278,6 @@ write_lat_log=str Same as write_bw_log, except that this option stores io
                and foo_lat.log. This helps fio_generate_plot fine the logs
                automatically.
 
-write_bw_log=str If given, write an IOPS log of the jobs in this job
-               file. See write_bw_log.
-
 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.log" is used. Even if the filename is given,