[PATCH] 'null' ioengine

Add a null io engine, which can be used to exercise and test/debug fio
itself. It doesn't transfer any data, just pretends to.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/HOWTO b/HOWTO
index 1176d2287f815439c680a38249a104682fcae64a..a5caea3db7a6201d74311b50a5d5d56bbbb77311 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -264,6 +264,10 @@ ioengine=str       Defines how the job issues io to the file. The following
                                we use read(2) and write(2) for asynchronous
                                io.
 
                                we use read(2) and write(2) for asynchronous
                                io.
 

+                       null    Doesn't transfer any data, just pretends
+                               to. This is mainly used to exercise fio
+                               itself and for debugging/testing purposes.
+

 iodepth=int    This defines how many io units to keep in flight against
                the file. The default is 1 for each file defined in this
                job, can be overridden with a larger value for higher
 iodepth=int    This defines how many io units to keep in flight against
                the file. The default is 1 for each file defined in this
                job, can be overridden with a larger value for higher

diff --git a/Makefile b/Makefile
index 4a4434d72a32c12ff04115c9ae6ac7b5e03e02b3..71b33c88c9c6adee0acc48f51a5f76af75b511c2 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -12,6 +12,7 @@ OBJS += engines/fio-engine-posixaio.o
 OBJS += engines/fio-engine-sg.o
 OBJS += engines/fio-engine-splice.o
 OBJS += engines/fio-engine-sync.o
 OBJS += engines/fio-engine-sg.o
 OBJS += engines/fio-engine-splice.o
 OBJS += engines/fio-engine-sync.o

+OBJS += engines/fio-engine-null.o

 
 INSTALL = install
 prefix = /usr/local
 
 INSTALL = install
 prefix = /usr/local

diff --git a/Makefile.FreeBSD b/Makefile.FreeBSD
index 894711721168c4298d4b7231ccdfd1eb5cb25803..ed75473be0a9bdfdbb376e2a9c6942dbf8f9e48d 100644 (file)
--- a/Makefile.FreeBSD
+++ b/Makefile.FreeBSD
@@ -9,6 +9,7 @@ OBJS += engines/fio-engine-cpu.o
 OBJS += engines/fio-engine-mmap.o
 OBJS += engines/fio-engine-posixaio.o
 OBJS += engines/fio-engine-sync.o
 OBJS += engines/fio-engine-mmap.o
 OBJS += engines/fio-engine-posixaio.o
 OBJS += engines/fio-engine-sync.o

+OBJS += engines/fio-engine-null.o

 
 all: depend $(PROGS) $(SCRIPTS)
 
 
 all: depend $(PROGS) $(SCRIPTS)
 

diff --git a/Makefile.solaris b/Makefile.solaris
index b487a05d9c89f2156f2e9dc942492d131197de1f..9eb2ebca3aa8bcbd2042861d1e1b8cb1b0aa7e69 100644 (file)
--- a/Makefile.solaris
+++ b/Makefile.solaris
@@ -9,6 +9,7 @@ OBJS += engines/fio-engine-cpu.o
 OBJS += engines/fio-engine-mmap.o
 OBJS += engines/fio-engine-posixaio.o
 OBJS += engines/fio-engine-sync.o
 OBJS += engines/fio-engine-mmap.o
 OBJS += engines/fio-engine-posixaio.o
 OBJS += engines/fio-engine-sync.o

+OBJS += engines/fio-engine-null.o

 
 all: depend $(PROGS) $(SCRIPTS)
 
 
 all: depend $(PROGS) $(SCRIPTS)
 

diff --git a/README b/README
index 04ff1eef18a36867e133f1c0a948936e3cc26e34..01cc19e9d69cf752ced1bb40b3709d5e2d78d121 100644 (file)
--- a/README
+++ b/README
@@ -90,7 +90,9 @@ The job file parameters are:
                        mmap for mmap'ed io, splice for using splice/vmsplice,
                        or sgio for direct SG_IO io. The latter only works on
                        Linux on SCSI (or SCSI-like devices, such as
                        mmap for mmap'ed io, splice for using splice/vmsplice,
                        or sgio for direct SG_IO io. The latter only works on
                        Linux on SCSI (or SCSI-like devices, such as

-                       usb-storage or sata/libata driven) devices.
+                       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,
        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,

diff --git a/engines/fio-engine-null.c b/engines/fio-engine-null.c
new file mode 100644 (file)
index 0000000..fc82947
--- /dev/null
+++ b/engines/fio-engine-null.c
@@ -0,0 +1,84 @@
+/*
+ * null engine - doesn't do any transfers. Used to test fio.
+ *
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <assert.h>
+
+#include "../fio.h"
+#include "../os.h"
+
+struct null_data {
+       struct io_u *last_io_u;
+};
+
+static int fio_null_getevents(struct thread_data *td, int fio_unused min,
+                             int max, struct timespec fio_unused *t)
+{
+       assert(max <= 1);
+
+       if (list_empty(&td->io_u_busylist))
+               return 0;
+
+       return 1;
+}
+
+static struct io_u *fio_null_event(struct thread_data *td, int event)
+{
+       struct null_data *nd = td->io_ops->data;
+
+       assert(event == 0);
+
+       return nd->last_io_u;
+}
+
+static int fio_null_queue(struct thread_data *td, struct io_u *io_u)
+{
+       struct null_data *nd = td->io_ops->data;
+
+       io_u->resid = 0;
+       io_u->error = 0;
+       nd->last_io_u = io_u;
+       return 0;
+}
+
+static void fio_null_cleanup(struct thread_data *td)
+{
+       if (td->io_ops->data) {
+               free(td->io_ops->data);
+               td->io_ops->data = NULL;
+       }
+}
+
+static int fio_null_init(struct thread_data *td)
+{
+       struct null_data *nd = malloc(sizeof(*nd));
+
+       nd->last_io_u = NULL;
+       td->io_ops->data = nd;
+       return 0;
+}
+
+static struct ioengine_ops ioengine = {
+       .name           = "null",
+       .version        = FIO_IOOPS_VERSION,
+       .init           = fio_null_init,
+       .queue          = fio_null_queue,
+       .getevents      = fio_null_getevents,
+       .event          = fio_null_event,
+       .cleanup        = fio_null_cleanup,
+       .flags          = FIO_SYNCIO,
+};
+
+static void fio_init fio_null_register(void)
+{
+       register_ioengine(&ioengine);
+}
+
+static void fio_exit fio_null_unregister(void)
+{
+       unregister_ioengine(&ioengine);
+}