parser: always use the fio logging instead of stderr/stdout

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 72a29a96eb1f05f69561fe85086fd9c5aa6e5cbc..24a0f3b09baed3951e85ac9e54185e181f81b073 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -319,8 +319,12 @@ rw=str             Type of io pattern. Accepted values are:
                a number of IO's to do before getting a new offset, this is
                one by appending a ':<nr>' to the end of the string given.
                For a random read, it would look like 'rw=randread:8' for
-               passing in an offset modifier with a value of 8. See the
-               'rw_sequencer' option.
+               passing in an offset modifier with a value of 8. If the
+               postfix is used with a sequential IO pattern, then the value
+               specified will be added to the generated offset for each IO.
+               For instance, using rw=write:4k will skip 4k for every
+               write. It turns sequential IO into sequential IO with holes.
+               See the 'rw_sequencer' option.
 
 rw_sequencer=str If an offset modifier is given by appending a number to
                the rw=<str> line, then this option controls how that
@@ -477,6 +481,13 @@ refill_buffers     If this option is given, fio will refill the IO buffers
                isn't specified, naturally. If data verification is enabled,
                refill_buffers is also automatically enabled.
 
+scramble_buffers=bool  If refill_buffers is too costly and the target is
+               using data deduplication, then setting this option will
+               slightly modify the IO buffer contents to defeat normal
+               de-dupe attempts. This is not enough to defeat more clever
+               block compression attempts, but it will stop naive dedupe of
+               blocks. Default: true.
+
 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
@@ -513,6 +524,16 @@ ioengine=str       Defines how the job issues io to the file. The following
                        libaio  Linux native asynchronous io. Note that Linux
                                may only support queued behaviour with
                                non-buffered IO (set direct=1 or buffered=0).
+                               This engine also has a sub-option,
+                               userspace_reap. To set it, use
+                               ioengine=libaio:userspace_reap. Normally, with
+                               the libaio engine in use, fio will use the
+                               io_getevents system call to reap newly returned
+                               events. With this flag turned on, the AIO ring
+                               will be read directly from user-space to reap
+                               events. The reaping mode is only enabled when
+                               polling for a minimum of 0 events (eg when
+                               iodepth_batch_complete=0).
 
                        posixaio glibc posix asynchronous io.
 
@@ -843,6 +864,9 @@ exitall             When one job finishes, terminate the rest. The default is
 bwavgtime=int  Average the calculated bandwidth over the given time. Value
                is specified in milliseconds.
 
+iopsavgtime=int        Average the calculated IOPS over the given time. Value
+               is specified in milliseconds.
+
 create_serialize=bool  If true, serialize the file creating for the jobs.
                        This may be handy to avoid interleaving of data
                        files, which may greatly depend on the filesystem
@@ -1083,6 +1107,9 @@ 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.
+
 lockmem=int    Pin down the specified amount of memory with mlock(2). Can
                potentially be used instead of removing memory or booting
                with less memory to simulate a smaller amount of memory.
@@ -1335,13 +1362,13 @@ Split up, the format is as follows:
 
        version, jobname, groupid, error
        READ status:
-               KB IO, bandwidth (KB/sec), runtime (msec)
+               Total IO (KB), bandwidth (KB/sec), runtime (msec)
                Submission latency: min, max, mean, deviation
                Completion latency: min, max, mean, deviation
                Total latency: min, max, mean, deviation
                Bw: min, max, aggregate percentage of total, mean, deviation
        WRITE status:
-               KB IO, bandwidth (KB/sec), runtime (msec)
+               Total IO (KB), bandwidth (KB/sec), runtime (msec)
                Submission latency: min, max, mean, deviation
                Completion latency: min, max, mean, deviation
                Total latency: min, max, mean, deviation