Allow offload with FAKEIO engines

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index e0403b0803f04cb04ef7a14832dd39b3803c34d8..2d8c7a0238fd20d77c1a1ee35e061ed16ab47cf8 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -1901,14 +1901,6 @@ I/O engine
                        single CPU at the desired rate. A job never finishes unless there is
                        at least one non-cpuio job.
 
-               **guasi**
-                       The GUASI I/O engine is the Generic Userspace Asynchronous Syscall
-                       Interface approach to async I/O. See
-
-                       http://www.xmailserver.org/guasi-lib.html
-
-                       for more info on GUASI.
-
                **rdma**
                        The RDMA I/O engine supports both RDMA memory semantics
                        (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the
@@ -2482,7 +2474,8 @@ I/O depth
        can increase latencies. The benefit is that fio can manage submission rates
        independently of the device completion rates. This avoids skewed latency
        reporting if I/O gets backed up on the device side (the coordinated omission
-       problem).
+       problem). Note that this option cannot reliably be used with async IO
+       engines.
 
 
 I/O rate
@@ -2861,15 +2854,10 @@ Threads, processes and job synchronization
        ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8
        ratio in how much one runs vs the other.
 
-.. option:: flow_watermark=int
-
-       The maximum value that the absolute value of the flow counter is allowed to
-       reach before the job must wait for a lower value of the counter.
-
 .. option:: flow_sleep=int
 
-       The period of time, in microseconds, to wait after the flow watermark has
-       been exceeded before retrying operations.
+       The period of time, in microseconds, to wait after the flow counter
+       has exceeded its proportion before retrying operations.
 
 .. option:: stonewall, wait_for_previous