poll: break on EINTR without complaining

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 3b60f58e0e367d1e593de9337b78b0ffb47f5d24..cc2df9b72421486d96d47e2d72220a0a5848c55a 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.
 
@@ -570,9 +591,9 @@ ioengine=str        Defines how the job issues io to the file. The following
                                for more info on GUASI.
 
                        rdma    The RDMA I/O engine  supports  both  RDMA
-                               memory semantic(RDMA_WRITE/RDMA_READ) and
-                               channel semantic(Send/Recv) in InfiniBand, RoCE
-                               and iWarp environment.
+                               memory semantics (RDMA_WRITE/RDMA_READ) and
+                               channel semantics (Send/Recv) for the
+                               InfiniBand, RoCE and iWARP protocols.
 
                        external Prefix to specify loading an external
                                IO engine object file. Append the engine
@@ -1335,13 +1356,13 @@ 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