fio_plugin: Update to 2.21, SPDK configure script

Documentation update - the plugin just works with 2.21 with no
changes.

Change-Id: If1fb2367a00065bfb5627d0d2af9683e5c909dc1
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.gerrithub.io/367734
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>

examples/nvme/fio_plugin/README.md

@@ -1,54 +1,67 @@
-Compiling
-----------
+# Compiling fio
 
 First, clone the fio source repository from https://github.com/axboe/fio
 
     git clone https://github.com/axboe/fio
 
-Then check out the fio 2.18 tag
+Then check out the fio 2.21:
 
-    cd fio && git checkout fio-2.18
+    cd fio && git checkout fio-2.21
 
-Finally, compile the code with
+Finally, compile the code:
 
-    ./configure && make
+    make
 
-Next, edit the CONFIG file located in the root of the SPDK repository and set CONFIG_FIO_PLUGIN
-to y and FIO_SOURCE_DIR to the location of the fio repository that was just created.
+# Compiling SPDK
 
-Further, you'll need to build DPDK with -fPIC set. You can do this by modifying your
-DPDK config file (i.e. config/defconfig_x86_64-native-linuxapp-gcc) to include the line
+First, clone the SPDK source repository from https://github.com/spdk/spdk
+
+    git clone https://github.com/spdk/spdk
+    git submodule update --init
+
+Then, run the SPDK configure script to enable fio (point it to the root of the fio repository):
+
+    cd spdk
+    ./configure --with-fio=/path/to/fio/repo <other configuration options>
+
+Finally, build SPDK:
+
+    make
+
+**Note to advanced users**: These steps assume you're using the DPDK submodule. If you are using your
+own version of DPDK, the fio plugin requires that DPDK be compiled with -fPIC. You can compile DPDK
+with -fPIC by modifying your DPDK configuration file and adding the line:
 
     EXTRA_CFLAGS=-fPIC
 
-At this point, build SPDK as per normal. The fio plugin will be placed in the same directory
-as this README.
-
-Usage
-------
+# Usage
 
 To use the SPDK fio plugin with fio, specify the plugin binary using LD_PRELOAD when running
 fio and set ioengine=spdk in the fio configuration file (see example_config.fio in the same
 directory as this README).
 
-    LD_PRELOAD=<path to fio_plugin binary> fio
+    LD_PRELOAD=<path to spdk repo>/examples/nvme/fio_plugin/fio_plugin fio
 
-To select NVMe devices, you simply pass an identifier as the filename in the format
+To select NVMe devices, you pass an SPDK Transport Identifier string as the filename. These are in the
+form:
 
     filename=key=value [key=value] ... ns=value
 
-Do not have any ':' in filename, otherwise it will be spilt into several file names. Also the
-NVMe namespaces start at 1, not 0! The namespace must also be specified at the end.
-
-Local PCIe NVMe devices will be specified using a PCI domain.bus.slot.func traddr format.  For example:
+Specifically, for local PCIe NVMe devices it will look like this:
 
     filename=trtype=PCIe traddr=0000.04.00.0 ns=1
 
-Remote devices accessed via NVMe over Fabrics will be specified based on the following example:
+And remote devices accessed via NVMe over Fabrics will look like this:
 
     filename=trtype=RDMA adrfam=IPv4 traddr=192.168.100.8 trsvcid=4420 ns=1
 
-Currently the SPDK fio plugin is limited to thread usage model, so fio jobs must also specify thread=1
+
+**Note**: The specification of the PCIe address should not use the normal ':'
+and instead only use '.'. This is a limitation in fio - it splits filenames on
+':'. Also, the NVMe namespaces start at 1, not 0, and the namespace must be
+specified at the end of the string.
+
+Currently the SPDK fio plugin is limited to the thread usage model, so fio jobs must also specify thread=1
 when using the SPDK fio plugin.
 
 fio also currently has a race condition on shutdown if dynamically loading the ioengine by specifying the