Add pread/pwrite support to sync engine

[fio.git] / README

diff --git a/README b/README
index 76aa22d69212e86b799ee15d2e4db3c5e5d4c987..3ef13eaa1a36d1453561ebd1dc330948637eb8b1 100644 (file)
--- a/README
+++ b/README
@@ -71,12 +71,22 @@ $ fio
        --help          Print this page
        --cmdhelp=cmd   Print command help, "all" for all of them
        --showcmd       Turn a job file into command line options
+       --readonly      Turn on safety read-only checks
+       --eta=when      When ETA estimate should be printed
+                       May be "always", "never" or "auto"
+
 
 Any parameters following the options will be assumed to be job files,
 unless they match a job file parameter. You can add as many as you want,
 each job file will be regarded as a separate group and fio will stonewall
 its execution.
 
+The --readonly switch is an extra safety guard to prevent accidentically
+turning on a write setting when that is not desired. Fio will only write
+if rw=write/randwrite/rw/randrw is given, but this extra safety net can
+be used as an extra precaution. It will also enable a write check in the
+io engine core to prevent an accidental write due to a fio bug.
+
 
 Job file
 --------
@@ -110,13 +120,14 @@ The job file parameters are:
        size=x          Set file size to x bytes (x string can include k/m/g)
        ioengine=x      'x' may be: aio/libaio/linuxaio for Linux aio,
                        posixaio for POSIX aio, sync for regular read/write io,
-                       mmap for mmap'ed io, syslet-rw for syslet driven
-                       read/write, splice for using splice/vmsplice,
-                       sgio for direct SG_IO io, net for network io, or cpuio
-                       for a cycler burner load. sgio only works on Linux on
-                       SCSI (or SCSI-like devices, such as usb-storage or
-                       sata/libata driven) devices. Fio also has a null io
-                       engine, which is mainly used for testing fio itself.
+                       psync for regular pread/pwrite io, mmap for mmap'ed io,
+                       syslet-rw for syslet driven read/write, splice for using
+                       splice/vmsplice, sgio for direct SG_IO io, net for
+                       network io, or cpuio for a cycler burner load. sgio only
+                       works on Linux on SCSI (or SCSI-like devices, such as
+                       usb-storage or sata/libata driven) devices. Fio also has
+                       a null io engine, which is mainly used for testing fio
+                       itself.
        iodepth=x       For async io, allow 'x' ios in flight
        overwrite=x     If 'x', layout a write file first.
        nrfiles=x       Spread io load over 'x' number of files per job,