helper_thread: remove impossible branch

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 88d10a171da9e373ee40e5844b2b1690c6b3db28..67fd83376fd3beffe1bf62e0e204981f2815eff9 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -53,8 +53,8 @@ bottom, it contains the following basic parameters:
 
        IO engine       How do we issue io? We could be memory mapping the
                        file, we could be using regular read/write, we
-                       could be using splice, async io, syslet, or even
-                       SG (SCSI generic sg).
+                       could be using splice, async io, or even SG
+                       (SCSI generic sg).
 
        IO depth        If the io engine is async, how large a queuing
                        depth do we want to maintain?
@@ -374,6 +374,11 @@ filename_format=str
                default of $jobname.$jobnum.$filenum will be used if
                no other format specifier is given.
 
+unique_filename=bool   To avoid collisions between networked clients, fio
+               defaults to prefixing any generated filenames (with a directory
+               specified) with the source of the client connecting. To disable
+               this behavior, set this option to 0.
+
 opendir=str    Tell fio to recursively add any file it can find in this
                directory and down the file system tree.
 
@@ -673,10 +678,23 @@ 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 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:
@@ -688,7 +706,9 @@ ioengine=str        Defines how the job issues io to the file. The following
 
                        vsync   Basic readv(2) or writev(2) IO.
 
-                       psyncv  Basic preadv(2) or pwritev(2) IO.
+                       pvsync  Basic preadv(2) or pwritev(2) IO.
+
+                       pvsync2 Basic preadv2(2) or pwritev2(2) IO.
 
                        libaio  Linux native asynchronous io. Note that Linux
                                may only support queued behaviour with
@@ -708,9 +728,6 @@ ioengine=str        Defines how the job issues io to the file. The following
                                vmsplice(2) to transfer data from user
                                space to the kernel.
 
-                       syslet-rw Use the syslet system calls to make
-                               regular read/write async.
-
                        sg      SCSI generic sg v3 io. May either be
                                synchronous using the SG_IO ioctl, or if
                                the target is an sg character device