[PATCH] First cut syslet async io support
Doesn't seem to perform as well as expected, needs investigation.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/engines/syslet-rw.c b/engines/syslet-rw.c
new file mode 100644
index 0000000..7099a6a
--- /dev/null
+++ b/engines/syslet-rw.c
@@ -0,0 +1,283 @@
+/*
+ * read/write() engine that uses syslet to be async
+ *
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <assert.h>
+
+#include "../fio.h"
+#include "../os.h"
+
+#ifdef FIO_HAVE_SYSLET
+
+struct syslet_data {
+ struct io_u **events;
+ unsigned int nr_events;
+
+ struct syslet_uatom **ring;
+ unsigned int ring_index;
+};
+
+/*
+ * Inspect the ring to see if we have completed events
+ */
+static void fio_syslet_complete(struct thread_data *td)
+{
+ struct syslet_data *sd = td->io_ops->data;
+
+ do {
+ struct syslet_uatom *atom;
+ struct io_u *io_u;
+ long ret;
+
+ atom = sd->ring[sd->ring_index];
+ if (!atom)
+ break;
+
+ sd->ring[sd->ring_index] = NULL;
+ if (++sd->ring_index == td->iodepth)
+ sd->ring_index = 0;
+
+ io_u = atom->private;
+ ret = *atom->ret_ptr;
+ if (ret > 0)
+ io_u->resid = io_u->xfer_buflen - ret;
+ else if (ret < 0)
+ io_u->error = ret;
+
+ sd->events[sd->nr_events++] = io_u;
+ } while (1);
+}
+
+static int fio_syslet_getevents(struct thread_data *td, int min,
+ int fio_unused max,
+ struct timespec fio_unused *t)
+{
+ struct syslet_data *sd = td->io_ops->data;
+ int get_events;
+ long ret;
+
+ do {
+ fio_syslet_complete(td);
+
+ /*
+ * do we have enough immediate completions?
+ */
+ if (sd->nr_events >= (unsigned int) min)
+ break;
+
+ /*
+ * OK, we need to wait for some events...
+ */
+ get_events = min - sd->nr_events;
+ ret = async_wait(get_events);
+ if (ret < 0)
+ return errno;
+ } while (1);
+
+ ret = sd->nr_events;
+ sd->nr_events = 0;
+ return ret;
+}
+
+static struct io_u *fio_syslet_event(struct thread_data *td, int event)
+{
+ struct syslet_data *sd = td->io_ops->data;
+
+ return sd->events[event];
+}
+
+static void init_atom(struct syslet_uatom *atom, int nr, void *arg0,
+ void *arg1, void *arg2, void *ret_ptr,
+ unsigned long flags, void *priv,struct syslet_uatom *next)
+{
+ atom->flags = flags;
+ atom->nr = nr;
+ atom->ret_ptr = ret_ptr;
+ atom->next = next;
+ atom->arg_ptr[0] = arg0;
+ atom->arg_ptr[1] = arg1;
+ atom->arg_ptr[2] = arg2;
+ atom->arg_ptr[3] = atom->arg_ptr[4] = atom->arg_ptr[5] = NULL;
+ atom->private = priv;
+}
+
+/*
+ * Use seek atom for sync
+ */
+static void fio_syslet_prep_sync(struct io_u *io_u, struct fio_file *f)
+{
+ init_atom(&io_u->seek_atom.atom, __NR_fsync, &f->fd, NULL, NULL,
+ &io_u->seek_atom.ret, SYSLET_STOP_ON_NEGATIVE, io_u, NULL);
+}
+
+static void fio_syslet_prep_rw(struct io_u *io_u, struct fio_file *f)
+{
+ int nr;
+
+ /*
+ * prepare seek
+ */
+ io_u->seek_atom.cmd = SEEK_SET;
+ init_atom(&io_u->seek_atom.atom, __NR_lseek, &f->fd, &io_u->offset,
+ &io_u->seek_atom.cmd, &io_u->seek_atom.ret,
+ SYSLET_STOP_ON_NEGATIVE | SYSLET_NO_COMPLETE |
+ SYSLET_SKIP_TO_NEXT_ON_STOP,
+ NULL, &io_u->rw_atom.atom);
+
+ /*
+ * prepare rw
+ */
+ if (io_u->ddir == DDIR_READ)
+ nr = __NR_read;
+ else
+ nr = __NR_write;
+
+ init_atom(&io_u->rw_atom.atom, nr, &f->fd, &io_u->xfer_buf,
+ &io_u->xfer_buflen, &io_u->rw_atom.ret,
+ SYSLET_STOP_ON_NEGATIVE | SYSLET_SKIP_TO_NEXT_ON_STOP,
+ io_u, NULL);
+}
+
+static int fio_syslet_prep(struct thread_data fio_unused *td, struct io_u *io_u)
+{
+ struct fio_file *f = io_u->file;
+
+ if (io_u->ddir == DDIR_SYNC)
+ fio_syslet_prep_sync(io_u, f);
+ else
+ fio_syslet_prep_rw(io_u, f);
+
+ return 0;
+}
+
+static int fio_syslet_queue(struct thread_data *td, struct io_u *io_u)
+{
+ struct syslet_data *sd = td->io_ops->data;
+ struct syslet_uatom *done;
+ long ret;
+
+ done = async_exec(&io_u->seek_atom.atom);
+ if (!done)
+ return 0;
+
+ /*
+ * completed sync
+ */
+ ret = io_u->rw_atom.ret;
+ if (ret != (long) io_u->xfer_buflen) {
+ if (ret > 0) {
+ io_u->resid = io_u->xfer_buflen - ret;
+ io_u->error = 0;
+ return ret;
+ } else
+ io_u->error = errno;
+ }
+
+ if (!io_u->error)
+ sd->events[sd->nr_events++] = io_u;
+ else
+ td_verror(td, io_u->error);
+
+ return io_u->error;
+}
+
+static void async_head_init(struct syslet_data *sd, unsigned int depth)
+{
+ struct async_head_user ahu;
+ unsigned long ring_size;
+
+ ring_size = sizeof(struct syslet_uatom *) * depth;
+ sd->ring = malloc(ring_size);
+ memset(sd->ring, 0, ring_size);
+
+ memset(&ahu, 0, sizeof(ahu));
+ ahu.completion_ring = sd->ring;
+ ahu.ring_size_bytes = ring_size;
+ ahu.max_nr_threads = -1;
+
+ if (async_register(&ahu, sizeof(ahu)) < 0)
+ perror("async_register");
+}
+
+static void async_head_exit(struct syslet_data *sd, unsigned int depth)
+{
+ struct async_head_user ahu;
+
+ memset(&ahu, 0, sizeof(ahu));
+ ahu.completion_ring = sd->ring;
+ ahu.ring_size_bytes = sizeof(struct syslet_uatom *) * depth;
+
+ if (async_unregister(&ahu, sizeof(ahu)) < 0)
+ perror("async_register");
+}
+
+static void fio_syslet_cleanup(struct thread_data *td)
+{
+ struct syslet_data *sd = td->io_ops->data;
+
+ if (sd) {
+ async_head_exit(sd, td->iodepth);
+ free(sd->events);
+ free(sd);
+ td->io_ops->data = NULL;
+ }
+}
+
+static int fio_syslet_init(struct thread_data *td)
+{
+ struct syslet_data *sd;
+
+ sd = malloc(sizeof(*sd));
+ memset(sd, 0, sizeof(*sd));
+ sd->events = malloc(sizeof(struct io_u *) * td->iodepth);
+ memset(sd->events, 0, sizeof(struct io_u *) * td->iodepth);
+ td->io_ops->data = sd;
+ async_head_init(sd, td->iodepth);
+ return 0;
+}
+
+static struct ioengine_ops ioengine = {
+ .name = "syslet-rw",
+ .version = FIO_IOOPS_VERSION,
+ .init = fio_syslet_init,
+ .prep = fio_syslet_prep,
+ .queue = fio_syslet_queue,
+ .getevents = fio_syslet_getevents,
+ .event = fio_syslet_event,
+ .cleanup = fio_syslet_cleanup,
+};
+
+#else /* FIO_HAVE_SYSLET */
+
+/*
+ * When we have a proper configure system in place, we simply wont build
+ * and install this io engine. For now install a crippled version that
+ * just complains and fails to load.
+ */
+static int fio_syslet_init(struct thread_data fio_unused *td)
+{
+ fprintf(stderr, "fio: syslet not available\n");
+ return 1;
+}
+
+static struct ioengine_ops ioengine = {
+ .name = "syslet-rw",
+ .version = FIO_IOOPS_VERSION,
+ .init = fio_syslet_init,
+};
+
+#endif /* FIO_HAVE_SYSLET */
+
+static void fio_init fio_syslet_register(void)
+{
+ register_ioengine(&ioengine);
+}
+
+static void fio_exit fio_syslet_unregister(void)
+{
+ unregister_ioengine(&ioengine);
+}