[PATCH v2 05/10] engines/libblkio: Add option libblkio_vectored

[Alberto Faria <afaria@redhat.com>]

When enabled, read and write requests are submitted as vectored requests
using blkioq_{readv,writev}(), instead of using blkioq_{read,write}().

Signed-off-by: Alberto Faria <afaria@redhat.com>
---
 HOWTO.rst          |  4 ++++
 engines/libblkio.c | 46 +++++++++++++++++++++++++++++++++++++++++-----
 fio.1              |  3 +++
 3 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/HOWTO.rst b/HOWTO.rst
index 2b3fe9c2..f77d76cc 100644
--- a/HOWTO.rst
+++ b/HOWTO.rst
@@ -2887,6 +2887,10 @@ with the caveat that when used on the command line, they must come after the
 	and are listed at
 	https://libblkio.gitlab.io/libblkio/blkio.html#properties
 
+.. option:: libblkio_vectored : [libblkio]
+
+	Submit vectored read and write requests.
+
 I/O depth
 ~~~~~~~~~
 
diff --git a/engines/libblkio.c b/engines/libblkio.c
index 6decfd39..219bb0dc 100644
--- a/engines/libblkio.c
+++ b/engines/libblkio.c
@@ -28,6 +28,7 @@ struct fio_blkio_data {
 	bool has_mem_region; /* whether mem_region is valid */
 	struct blkio_mem_region mem_region; /* only if allocated by libblkio */
 
+	struct iovec *iovecs; /* for vectored requests */
 	struct blkio_completion *completions;
 };
 
@@ -39,6 +40,7 @@ struct fio_blkio_options {
 	char *pre_start_props;
 
 	unsigned int hipri;
+	unsigned int vectored;
 };
 
 static struct fio_option options[] = {
@@ -78,6 +80,15 @@ static struct fio_option options[] = {
 		.category = FIO_OPT_C_ENGINE,
 		.group	= FIO_OPT_G_LIBBLKIO,
 	},
+	{
+		.name	= "libblkio_vectored",
+		.lname	= "Use blkioq_{readv,writev}()",
+		.type	= FIO_OPT_STR_SET,
+		.off1	= offsetof(struct fio_blkio_options, vectored),
+		.help	= "Use blkioq_{readv,writev}() instead of blkioq_{read,write}()",
+		.category = FIO_OPT_C_ENGINE,
+		.group	= FIO_OPT_G_LIBBLKIO,
+	},
 	{
 		.name = NULL,
 	},
@@ -249,8 +260,9 @@ static int fio_blkio_init(struct thread_data *td)
 		return 1;
 	}
 
+	data->iovecs = calloc(td->o.iodepth, sizeof(data->iovecs[0]));
 	data->completions = calloc(td->o.iodepth, sizeof(data->completions[0]));
-	if (!data->completions) {
+	if (!data->iovecs || !data->completions) {
 		log_err("fio: calloc() failed\n");
 		goto err_free;
 	}
@@ -288,6 +300,7 @@ err_blkio_destroy:
 	blkio_destroy(&data->b);
 err_free:
 	free(data->completions);
+	free(data->iovecs);
 	free(data);
 	return 1;
 }
@@ -340,6 +353,7 @@ static void fio_blkio_cleanup(struct thread_data *td)
 	if (data) {
 		blkio_destroy(&data->b);
 		free(data->completions);
+		free(data->iovecs);
 		free(data);
 	}
 }
@@ -405,18 +419,40 @@ static int fio_blkio_open_file(struct thread_data *td, struct fio_file *f)
 static enum fio_q_status fio_blkio_queue(struct thread_data *td,
 					 struct io_u *io_u)
 {
+	const struct fio_blkio_options *options = td->eo;
 	struct fio_blkio_data *data = td->io_ops_data;
 
 	fio_ro_check(td, io_u);
 
 	switch (io_u->ddir) {
 		case DDIR_READ:
-			blkioq_read(data->q, io_u->offset, io_u->xfer_buf,
-				    (size_t)io_u->xfer_buflen, io_u, 0);
+			if (options->vectored) {
+				struct iovec *iov = &data->iovecs[io_u->index];
+				iov->iov_base = io_u->xfer_buf;
+				iov->iov_len = (size_t)io_u->xfer_buflen;
+
+				blkioq_readv(data->q, io_u->offset, iov, 1,
+					     io_u, 0);
+			} else {
+				blkioq_read(data->q, io_u->offset,
+					    io_u->xfer_buf,
+					    (size_t)io_u->xfer_buflen, io_u, 0);
+			}
 			break;
 		case DDIR_WRITE:
-			blkioq_write(data->q, io_u->offset, io_u->xfer_buf,
-				     (size_t)io_u->xfer_buflen, io_u, 0);
+			if (options->vectored) {
+				struct iovec *iov = &data->iovecs[io_u->index];
+				iov->iov_base = io_u->xfer_buf;
+				iov->iov_len = (size_t)io_u->xfer_buflen;
+
+				blkioq_writev(data->q, io_u->offset, iov, 1,
+					      io_u, 0);
+			} else {
+				blkioq_write(data->q, io_u->offset,
+					     io_u->xfer_buf,
+					     (size_t)io_u->xfer_buflen, io_u,
+					     0);
+			}
 			break;
 		case DDIR_TRIM:
 			blkioq_discard(data->q, io_u->offset, io_u->xfer_buflen,
diff --git a/fio.1 b/fio.1
index 7f97e940..9b8995b5 100644
--- a/fio.1
+++ b/fio.1
@@ -2634,6 +2634,9 @@ properties depend on the libblkio version in use and are listed at
 .TP
 .BI (libblkio)hipri
 Use poll queues.
+.TP
+.BI (libblkio)libblkio_vectored
+Submit vectored read and write requests.
 .SS "I/O depth"
 .TP
 .BI iodepth \fR=\fPint
-- 
2.38.1