Add support for non-uniformly random file service type

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 1f523d384ad85f64b38889aa364a4b0f150fec66..9ed2c5f5580365c69664eecb651f7e1b4065df7b 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -673,10 +673,23 @@ file_service_type=str  Defines how fio decides which file from a job to
                                the next. Multiple files can still be
                                open depending on 'openfiles'.
 
                                the next. Multiple files can still be
                                open depending on 'openfiles'.
 

-               The string can have a number appended, indicating how
-               often to switch to a new file. So if option random:4 is
-               given, fio will switch to a new random file after 4 ios
-               have been issued.
+                       zipf    Use a zipfian distribution to decide what file
+                               to access.
+
+                       pareto  Use a pareto distribution to decide what file
+                               to access.
+
+                       gauss   Use a gaussian (normal) distribution to decide
+                               what file to access.
+
+               For random, roundrobin, and sequential, a postfix can be
+               appended to tell fio how many I/Os to issue before switching
+               to a new file. For example, specifying
+               'file_service_type=random:8' would cause fio to issue 8 I/Os
+               before selecting a new file at random. For the non-uniform
+               distributions, a floating point postfix can be given to
+               influence how the distribution is skewed. See
+               'random_distribution' for a description of how that would work.

 
 ioengine=str   Defines how the job issues io to the file. The following
                types are defined:
 
 ioengine=str   Defines how the job issues io to the file. The following
                types are defined:


@@ -798,6 +811,9 @@ ioengine=str        Defines how the job issues io to the file. The following
                                overwriting. The writetrim mode works well
                                for this constraint.
 
                                overwriting. The writetrim mode works well
                                for this constraint.
 

+                       pmemblk Read and write through the NVML libpmemblk
+                               interface.
+

                        external Prefix to specify loading an external
                                IO engine object file. Append the engine
                                filename, eg ioengine=external:/tmp/foo.o
                        external Prefix to specify loading an external
                                IO engine object file. Append the engine
                                filename, eg ioengine=external:/tmp/foo.o


@@ -1263,10 +1279,14 @@ exitall_on_error        When one job finishes in error, terminate the rest. The
                default is to wait for each job to finish.
 
 bwavgtime=int  Average the calculated bandwidth over the given time. Value
                default is to wait for each job to finish.
 
 bwavgtime=int  Average the calculated bandwidth over the given time. Value

-               is specified in milliseconds.
+               is specified in milliseconds. If the job also does bandwidth
+               logging through 'write_bw_log', then the minimum of this option
+               and 'log_avg_msec' will be used.  Default: 500ms.

 
 iopsavgtime=int        Average the calculated IOPS over the given time. Value
 
 iopsavgtime=int        Average the calculated IOPS over the given time. Value

-               is specified in milliseconds.
+               is specified in milliseconds. If the job also does IOPS logging
+               through 'write_iops_log', then the minimum of this option and
+               'log_avg_msec' will be used.  Default: 500ms.

 
 create_serialize=bool  If true, serialize the file creating for the jobs.
                        This may be handy to avoid interleaving of data
 
 create_serialize=bool  If true, serialize the file creating for the jobs.
                        This may be handy to avoid interleaving of data