On 12/6/2024 7:23 AM, Keith Busch wrote:
> From: Keith Busch <kbusch@xxxxxxxxxx>
>
> Adds a new attribute type to specify a write stream per-IO.
>
> Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
> ---
> include/uapi/linux/io_uring.h | 9 ++++++++-
> io_uring/rw.c | 28 +++++++++++++++++++++++++++-
> 2 files changed, 35 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index 5fa38467d6070..263cd57aae72d 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -123,7 +123,14 @@ struct io_uring_attr_pi {
> __u64 rsvd;
> };
>
> -#define IORING_RW_ATTR_FLAGS_SUPPORTED (IORING_RW_ATTR_FLAG_PI)
> +#define IORING_RW_ATTR_FLAG_WRITE_STREAM (1U << 1)
> +struct io_uring_write_stream {
> + __u16 write_stream;
> + __u8 rsvd[6];
> +};
So this needs 8 bytes. Maybe passing just 'u16 write_stream' is better?
Or do you expect future additions here (to keep rsvd).
Optimization is possible (now or in future) if it's 4 bytes or smaller,
as that can be placed in SQE along with a new RW attribute flag that
says it's placed inline. Like this -
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -92,6 +92,10 @@ struct io_uring_sqe {
__u16 addr_len;
__u16 __pad3[1];
};
+ struct {
+ __u16 write_hint;
+ __u16 __rsvd[1];
+ };
};
union {
struct {
@@ -113,6 +117,7 @@ struct io_uring_sqe {
/* sqe->attr_type_mask flags */
#define IORING_RW_ATTR_FLAG_PI (1U << 0)
+#define IORING_RW_ATTR_FLAG_WRITE_STREAM_INLINE (1U << 1)
