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

[Vincent Fu <vincentfu@gmail.com>]

On 11/21/22 13:28, Alberto Faria wrote:
> 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 cdea3258..b9c7c8df 100644
> --- a/HOWTO.rst
> +++ b/HOWTO.rst
> @@ -2875,6 +2875,10 @@ with the caveat that when used on the command line, they must come after the
>   	set after the engine sets any other properties, so those can be
>   	overriden.
>   
> +.. option:: libblkio_vectored=bool : [libblkio]

See my response to the hipri patch regarding the difference between 
booleans and FIO_OPT_STR_SET. I don't have strong feelings regarding 
whether this should be a boolean or FIO_OPT_STR_SET but if the type 
listed in the HOWTO and manpage is boolean then the type in the options 
struct should be FIO_OPT_BOOL. No type should be listed when it's 
FIO_OPT_STR_SET.

> +
> +	Submit vectored read and write requests. Default is 0.
> +
>   I/O depth
>   ~~~~~~~~~
>   
> diff --git a/engines/libblkio.c b/engines/libblkio.c
> index d2ade3f1..dcf701ad 100644
> --- a/engines/libblkio.c
> +++ b/engines/libblkio.c
> @@ -28,6 +28,7 @@ struct fio_blkio_options {
>   	char *pre_start_props;
>   
>   	unsigned int hipri;
> +	unsigned int vectored;
>   };
>   
>   static struct fio_option options[] = {
> @@ -68,6 +69,15 @@ 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,
> @@ -251,6 +261,7 @@ 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;
>   };
>   
> @@ -267,8 +278,9 @@ static int fio_blkio_init(struct thread_data *td)
>   		goto err_free;
>   	}
>   
> +	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;
>   	}
> @@ -310,6 +322,7 @@ err_blkio_destroy:
>   	blkio_destroy(&data->b);
>   err_free:
>   	free(data->completions);
> +	free(data->iovecs);
>   	free(data);
>   	return 1;
>   }
> @@ -362,6 +375,7 @@ static void fio_blkio_cleanup(struct thread_data *td)
>   	if (data) {
>   		blkio_destroy(&data->b);
>   		free(data->completions);
> +		free(data->iovecs);
>   		free(data);
>   	}
>   }
> @@ -432,19 +446,41 @@ 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:
> diff --git a/fio.1 b/fio.1
> index 7c1b315a..a403b415 100644
> --- a/fio.1
> +++ b/fio.1
> @@ -2623,6 +2623,9 @@ the engine sets any other properties, so those can be overriden.
>   .TP
>   .BI (libblkio)hipri \fR=\fPbool
>   Use poll queues.
> +.TP
> +.BI (libblkio)libblkio_vectored \fR=\fPbool
> +Submit vectored read and write requests. Default is 0.
>   .SS "I/O depth"
>   .TP
>   .BI iodepth \fR=\fPint