Improve accuracy of rate= option

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 724b604b19c1116b87f32cc4b385e36e92dcd445..41edcf1a8ff820e09d915a4e69ceca11d8bb619c 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -267,7 +267,7 @@ filename=str        Fio normally makes up a filename based on the job name,
                files between threads in a job or several jobs, specify
                a filename for each of them to override the default. If
                the ioengine used is 'net', the filename is the host, port,
-               and protocol to use in the format of =host/port/protocol.
+               and protocol to use in the format of =host,port,protocol.
                See ioengine=net for more. If the ioengine is file based, you
                can specify a number of files by separating the names with a
                ':' colon. So if you wanted a job to open /dev/sda and /dev/sdb
@@ -481,6 +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
@@ -857,6 +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
@@ -971,7 +981,7 @@ verify_fatal=bool   Normally fio will keep checking the entire contents
 verify_dump=bool       If set, dump the contents of both the original data
                block and the data block we read off disk to files. This
                allows later analysis to inspect just what kind of data
-               corruption occurred. On by default.
+               corruption occurred. Off by default.
 
 verify_async=int       Fio will normally verify IO inline from the submitting
                thread. This option takes an integer describing how many
@@ -1097,6 +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.
@@ -1347,27 +1360,43 @@ signify that change.
 
 Split up, the format is as follows:
 
-       version, jobname, groupid, error
+       terse version, fio version, jobname, groupid, error
        READ status:
-               KB IO, bandwidth (KB/sec), runtime (msec)
+               Total IO (KB), bandwidth (KB/sec), IOPS, runtime (msec)
                Submission latency: min, max, mean, deviation
                Completion latency: min, max, mean, deviation
+               Completion latency percentiles: 20 fields (see below)
                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), IOPS, runtime (msec)
                Submission latency: min, max, mean, deviation
                Completion latency: min, max, mean, deviation
+               Completion latency percentiles: 20 fields (see below)
                Total latency: min, max, mean, deviation
                Bw: min, max, aggregate percentage of total, mean, deviation
        CPU usage: user, system, context switches, major faults, minor faults
        IO depths: <=1, 2, 4, 8, 16, 32, >=64
        IO latencies microseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
        IO latencies milliseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
+       Disk utilization: Disk name, Read ios, write ios,
+                         Read merges, write merges,
+                         Read ticks, write ticks,
+                         Time spent in queue, disk utilization percentage
        Additional Info (dependant on continue_on_error, default off): total # errors, first error code 
        
        Additional Info (dependant on description being set): Text description
 
+Completion latency percentiles can be a grouping of up to 20 sets, so
+for the terse output fio writes all of them. Each field will look like this:
+
+       1.00%=6112
+
+which is the Xth percentile, and the usec latency associated with it.
+
+For disk utilization, all disks used by fio are shown. So for each disk
+there will be a disk utilization section.
+
 
 8.0 Trace file format
 ---------------------