From: Tomohiro Kusumi <tkusumi@xxxxxxxxxx>
Add an example of ioengine specific options, which can/should exist
within each ioengine code. Also fix/add documentation.
Also see e59b9e11('move skip_bad= option to engines/mtd.c').
Signed-off-by: Tomohiro Kusumi <tkusumi@xxxxxxxxxx>
---
HOWTO | 4 +++-
engines/skeleton_external.c | 32 +++++++++++++++++++++++++++++++-
fio.1 | 4 +++-
3 files changed, 37 insertions(+), 3 deletions(-)
diff --git a/HOWTO b/HOWTO
index 3a720c3..2a70b7c 100644
--- a/HOWTO
+++ b/HOWTO
@@ -1791,7 +1791,9 @@ I/O engine
**external**
Prefix to specify loading an external I/O engine object file. Append
the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load
- ioengine :file:`foo.o` in :file:`/tmp`.
+ ioengine :file:`foo.o` in :file:`/tmp`. The path can be either
+ absolute or relative. See :file:`engines/skeleton_external.c` for
+ details of writing an external I/O engine.
I/O engine specific parameters
diff --git a/engines/skeleton_external.c b/engines/skeleton_external.c
index 4bebcc4..56f89f9 100644
--- a/engines/skeleton_external.c
+++ b/engines/skeleton_external.c
@@ -3,7 +3,8 @@
*
* Should be compiled with:
*
- * gcc -Wall -O2 -g -shared -rdynamic -fPIC -o engine.o engine.c
+ * gcc -Wall -O2 -g -shared -rdynamic -fPIC -o skeleton_external.o skeleton_external.c
+ * (also requires -D_GNU_SOURCE -DCONFIG_STRSEP on Linux)
*
*/
#include <stdio.h>
@@ -13,6 +14,7 @@
#include <assert.h>
#include "../fio.h"
+#include "../optgroup.h"
/*
* The core of the module is identical to the ones included with fio,
@@ -21,6 +23,32 @@
*/
/*
+ * The io engine can define its own options within the io engine source.
+ * The option member must not be at offset 0, due to the way fio parses
+ * the given option. Just add a padding pointer unless the io engine has
+ * something usable.
+ */
+struct fio_skeleton_options {
+ void *pad; /* avoid ->off1 of fio_option becomes 0 */
+ unsigned int dummy;
+};
+
+static struct fio_option options[] = {
+ {
+ .name = "dummy",
+ .lname = "ldummy",
+ .type = FIO_OPT_STR_SET,
+ .off1 = offsetof(struct fio_skeleton_options, dummy),
+ .help = "Set dummy",
+ .category = FIO_OPT_C_ENGINE, /* always use this */
+ .group = FIO_OPT_G_INVALID, /* this can be different */
+ },
+ {
+ .name = NULL,
+ },
+};
+
+/*
* The ->event() hook is called to match an event number with an io_u.
* After the core has called ->getevents() and it has returned eg 3,
* the ->event() hook must return the 3 events that have completed for
@@ -140,4 +168,6 @@ struct ioengine_ops ioengine = {
.cleanup = fio_skeleton_cleanup,
.open_file = fio_skeleton_open,
.close_file = fio_skeleton_close,
+ .options = options,
+ .option_struct_size = sizeof(struct fio_skeleton_options),
};
diff --git a/fio.1 b/fio.1
index 5b63dfd..97133da 100644
--- a/fio.1
+++ b/fio.1
@@ -1572,7 +1572,9 @@ Read and write using device DAX to a persistent memory device (e.g.,
.B external
Prefix to specify loading an external I/O engine object file. Append
the engine filename, e.g. `ioengine=external:/tmp/foo.o' to load
-ioengine `foo.o' in `/tmp'.
+ioengine `foo.o' in `/tmp'. The path can be either
+absolute or relative. See `engines/skeleton_external.c' in the fio source for
+details of writing an external I/O engine.
.SS "I/O engine specific parameters"
In addition, there are some parameters which are only valid when a specific
\fBioengine\fR is in use. These are used identically to normal parameters,
--
2.9.5
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