2 * Skeleton for a sample external io engine
4 * Should be compiled with:
6 * gcc -Wall -O2 -g -shared -rdynamic -fPIC -o engine.o engine.c
19 * The core of the module is identical to the ones included with fio,
20 * read those. You cannot use register_ioengine() and unregister_ioengine()
21 * for external modules, they should be gotten through dlsym()
25 * The ->event() hook is called to match an event number with an io_u.
26 * After the core has called ->getevents() and it has returned eg 3,
27 * the ->event() hook must return the 3 events that have completed for
28 * subsequent calls to ->event() with [0-2]. Required.
30 static struct io_u *fio_skeleton_event(struct thread_data *td, int event)
36 * The ->getevents() hook is used to reap completion events from an async
37 * io engine. It returns the number of completed events since the last call,
38 * which may then be retrieved by calling the ->event() hook with the event
41 static int fio_skeleton_getevents(struct thread_data *td, int min, int max,
48 * The ->cancel() hook attempts to cancel the io_u. Only relevant for
49 * async io engines, and need not be supported.
51 static int fio_skeleton_cancel(struct thread_data *td, struct io_u *io_u)
57 * The ->queue() hook is responsible for initiating io on the io_u
58 * being passed in. If the io engine is a synchronous one, io may complete
59 * before ->queue() returns. Required.
61 * The io engine must transfer in the direction noted by io_u->ddir
62 * to the buffer pointed to by io_u->xfer_buf for as many bytes as
63 * io_u->xfer_buflen. Residual data count may be set in io_u->residual
64 * for a short read/write. Should return 0 for io_u complete, < 0 for
65 * an error, and > 0 for the number of bytes transferred.
67 static int fio_skeleton_queue(struct thread_data *td, struct io_u *io_u)
73 * The ->prep() function is called for each io_u prior to being submitted
74 * with ->queue(). This hook allows the io engine to perform any
75 * preperatory actions on the io_u, before being submitted. Not required.
77 static int fio_skeleton_prep(struct thread_data *td, struct io_u *io_u)
83 * The init function is called once per thread/process, and should set up
84 * any structures that this io engine requires to keep track of io. Not
87 static int fio_skeleton_init(struct thread_data *td)
93 * This is paired with the ->init() funtion and is called when a thread is
94 * done doing io. Should tear down anything setup by the ->init() function.
97 static void fio_skeleton_cleanup(struct thread_data *td)
102 * Note that the structure is exported, so that fio can get it via
103 * dlsym(..., "ioengine");
105 struct ioengine_ops ioengine = {
106 .name = "engine_name",
107 .version = FIO_IOOPS_VERSION,
108 .init = fio_skeleton_init,
109 .prep = fio_skeleton_prep,
110 .queue = fio_skeleton_queue,
111 .cancel = fio_skeleton_cancel,
112 .getevents = fio_skeleton_getevents,
113 .event = fio_skeleton_event,
114 .cleanup = fio_skeleton_cleanup,