* Re: [PATCH 1/1] io_uring/net: introduce IORING_SEND_ZC_REPORT_USAGE flag
2022-10-27 18:34 ` [PATCH 1/1] io_uring/net: introduce IORING_SEND_ZC_REPORT_USAGE flag Stefan Metzmacher
@ 2022-10-28 13:12 ` Pavel Begunkov
2022-11-02 12:33 ` Pavel Begunkov
2022-11-02 14:02 ` Jens Axboe
2 siblings, 0 replies; 4+ messages in thread
From: Pavel Begunkov @ 2022-10-28 13:12 UTC (permalink / raw)
To: Stefan Metzmacher, io-uring
On 10/27/22 19:34, Stefan Metzmacher wrote:
> It might be useful for applications to detect if a zero copy
> transfer with SEND[MSG]_ZC was actually possible or not.
> The application can fallback to plain SEND[MSG] in order
> to avoid the overhead of two cqes per request.
> Or it can generate a log message that could indicate
> to an administrator that no zero copy was possible
> and could explain degraded performance.
From a quick look seems good, I'll test and double check
when I'm back on tuesday
> Link: https://lore.kernel.org/io-uring/[email protected]/T/#m2b0d9df94ce43b0e69e6c089bdff0ce6babbdfaa
> Cc: Pavel Begunkov <[email protected]>
> Signed-off-by: Stefan Metzmacher <[email protected]>
> ---
> include/uapi/linux/io_uring.h | 18 ++++++++++++++++++
> io_uring/net.c | 6 +++++-
> io_uring/notif.c | 12 ++++++++++++
> io_uring/notif.h | 3 +++
> 4 files changed, 38 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index ab7458033ee3..423f98781a20 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -296,10 +296,28 @@ enum io_uring_op {
> *
> * IORING_RECVSEND_FIXED_BUF Use registered buffers, the index is stored in
> * the buf_index field.
> + *
> + * IORING_SEND_ZC_REPORT_USAGE
> + * If set, SEND[MSG]_ZC should report
> + * the zerocopy usage in cqe.res
> + * for the IORING_CQE_F_NOTIF cqe.
> + * 0 is reported if zerocopy was actually possible.
> + * IORING_NOTIF_USAGE_ZC_COPIED if data was copied
> + * (at least partially).
> */
> #define IORING_RECVSEND_POLL_FIRST (1U << 0)
> #define IORING_RECV_MULTISHOT (1U << 1)
> #define IORING_RECVSEND_FIXED_BUF (1U << 2)
> +#define IORING_SEND_ZC_REPORT_USAGE (1U << 3)
> +
> +/*
> + * cqe.res for IORING_CQE_F_NOTIF if
> + * IORING_SEND_ZC_REPORT_USAGE was requested
> + *
> + * It should be treated as a flag, all other
> + * bits of cqe.res should be treated as reserved!
> + */
> +#define IORING_NOTIF_USAGE_ZC_COPIED (1U << 31)
>
> /*
> * accept flags stored in sqe->ioprio
> diff --git a/io_uring/net.c b/io_uring/net.c
> index 15dea91625e2..0a8cdc5ae7af 100644
> --- a/io_uring/net.c
> +++ b/io_uring/net.c
> @@ -939,7 +939,8 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>
> zc->flags = READ_ONCE(sqe->ioprio);
> if (zc->flags & ~(IORING_RECVSEND_POLL_FIRST |
> - IORING_RECVSEND_FIXED_BUF))
> + IORING_RECVSEND_FIXED_BUF |
> + IORING_SEND_ZC_REPORT_USAGE))
> return -EINVAL;
> notif = zc->notif = io_alloc_notif(ctx);
> if (!notif)
> @@ -957,6 +958,9 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> req->imu = READ_ONCE(ctx->user_bufs[idx]);
> io_req_set_rsrc_node(notif, ctx, 0);
> }
> + if (zc->flags & IORING_SEND_ZC_REPORT_USAGE) {
> + io_notif_to_data(notif)->zc_report = true;
> + }
>
> if (req->opcode == IORING_OP_SEND_ZC) {
> if (READ_ONCE(sqe->__pad3[0]))
> diff --git a/io_uring/notif.c b/io_uring/notif.c
> index e37c6569d82e..4bfef10161fa 100644
> --- a/io_uring/notif.c
> +++ b/io_uring/notif.c
> @@ -18,6 +18,10 @@ static void __io_notif_complete_tw(struct io_kiocb *notif, bool *locked)
> __io_unaccount_mem(ctx->user, nd->account_pages);
> nd->account_pages = 0;
> }
> +
> + if (nd->zc_report && (nd->zc_copied || !nd->zc_used))
> + notif->cqe.res |= IORING_NOTIF_USAGE_ZC_COPIED;
> +
> io_req_task_complete(notif, locked);
> }
>
> @@ -28,6 +32,13 @@ static void io_uring_tx_zerocopy_callback(struct sk_buff *skb,
> struct io_notif_data *nd = container_of(uarg, struct io_notif_data, uarg);
> struct io_kiocb *notif = cmd_to_io_kiocb(nd);
>
> + if (nd->zc_report) {
> + if (success && !nd->zc_used && skb)
> + WRITE_ONCE(nd->zc_used, true);
> + else if (!success && !nd->zc_copied)
> + WRITE_ONCE(nd->zc_copied, true);
> + }
> +
> if (refcount_dec_and_test(&uarg->refcnt)) {
> notif->io_task_work.func = __io_notif_complete_tw;
> io_req_task_work_add(notif);
> @@ -55,6 +66,7 @@ struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx)
> nd->account_pages = 0;
> nd->uarg.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
> nd->uarg.callback = io_uring_tx_zerocopy_callback;
> + nd->zc_report = nd->zc_used = nd->zc_copied = false;
> refcount_set(&nd->uarg.refcnt, 1);
> return notif;
> }
> diff --git a/io_uring/notif.h b/io_uring/notif.h
> index 5b4d710c8ca5..4ae696273c78 100644
> --- a/io_uring/notif.h
> +++ b/io_uring/notif.h
> @@ -13,6 +13,9 @@ struct io_notif_data {
> struct file *file;
> struct ubuf_info uarg;
> unsigned long account_pages;
> + bool zc_report;
> + bool zc_used;
> + bool zc_copied;
> };
>
> void io_notif_flush(struct io_kiocb *notif);
--
Pavel Begunkov
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/1] io_uring/net: introduce IORING_SEND_ZC_REPORT_USAGE flag
2022-10-27 18:34 ` [PATCH 1/1] io_uring/net: introduce IORING_SEND_ZC_REPORT_USAGE flag Stefan Metzmacher
2022-10-28 13:12 ` Pavel Begunkov
@ 2022-11-02 12:33 ` Pavel Begunkov
2022-11-02 14:02 ` Jens Axboe
2 siblings, 0 replies; 4+ messages in thread
From: Pavel Begunkov @ 2022-11-02 12:33 UTC (permalink / raw)
To: Stefan Metzmacher, io-uring
On 10/27/22 19:34, Stefan Metzmacher wrote:
> It might be useful for applications to detect if a zero copy
> transfer with SEND[MSG]_ZC was actually possible or not.
> The application can fallback to plain SEND[MSG] in order
> to avoid the overhead of two cqes per request.
> Or it can generate a log message that could indicate
> to an administrator that no zero copy was possible
> and could explain degraded performance.
Looks good,
Reviewed-by: Pavel Begunkov <[email protected]>
> Link: https://lore.kernel.org/io-uring/[email protected]/T/#m2b0d9df94ce43b0e69e6c089bdff0ce6babbdfaa
> Cc: Pavel Begunkov <[email protected]>
> Signed-off-by: Stefan Metzmacher <[email protected]>
> ---
> include/uapi/linux/io_uring.h | 18 ++++++++++++++++++
> io_uring/net.c | 6 +++++-
> io_uring/notif.c | 12 ++++++++++++
> io_uring/notif.h | 3 +++
> 4 files changed, 38 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index ab7458033ee3..423f98781a20 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -296,10 +296,28 @@ enum io_uring_op {
> *
> * IORING_RECVSEND_FIXED_BUF Use registered buffers, the index is stored in
> * the buf_index field.
> + *
> + * IORING_SEND_ZC_REPORT_USAGE
> + * If set, SEND[MSG]_ZC should report
> + * the zerocopy usage in cqe.res
> + * for the IORING_CQE_F_NOTIF cqe.
> + * 0 is reported if zerocopy was actually possible.
> + * IORING_NOTIF_USAGE_ZC_COPIED if data was copied
> + * (at least partially).
> */
> #define IORING_RECVSEND_POLL_FIRST (1U << 0)
> #define IORING_RECV_MULTISHOT (1U << 1)
> #define IORING_RECVSEND_FIXED_BUF (1U << 2)
> +#define IORING_SEND_ZC_REPORT_USAGE (1U << 3)
> +
> +/*
> + * cqe.res for IORING_CQE_F_NOTIF if
> + * IORING_SEND_ZC_REPORT_USAGE was requested
> + *
> + * It should be treated as a flag, all other
> + * bits of cqe.res should be treated as reserved!
> + */
> +#define IORING_NOTIF_USAGE_ZC_COPIED (1U << 31)
>
> /*
> * accept flags stored in sqe->ioprio
> diff --git a/io_uring/net.c b/io_uring/net.c
> index 15dea91625e2..0a8cdc5ae7af 100644
> --- a/io_uring/net.c
> +++ b/io_uring/net.c
> @@ -939,7 +939,8 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>
> zc->flags = READ_ONCE(sqe->ioprio);
> if (zc->flags & ~(IORING_RECVSEND_POLL_FIRST |
> - IORING_RECVSEND_FIXED_BUF))
> + IORING_RECVSEND_FIXED_BUF |
> + IORING_SEND_ZC_REPORT_USAGE))
> return -EINVAL;
> notif = zc->notif = io_alloc_notif(ctx);
> if (!notif)
> @@ -957,6 +958,9 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> req->imu = READ_ONCE(ctx->user_bufs[idx]);
> io_req_set_rsrc_node(notif, ctx, 0);
> }
> + if (zc->flags & IORING_SEND_ZC_REPORT_USAGE) {
> + io_notif_to_data(notif)->zc_report = true;
> + }
>
> if (req->opcode == IORING_OP_SEND_ZC) {
> if (READ_ONCE(sqe->__pad3[0]))
> diff --git a/io_uring/notif.c b/io_uring/notif.c
> index e37c6569d82e..4bfef10161fa 100644
> --- a/io_uring/notif.c
> +++ b/io_uring/notif.c
> @@ -18,6 +18,10 @@ static void __io_notif_complete_tw(struct io_kiocb *notif, bool *locked)
> __io_unaccount_mem(ctx->user, nd->account_pages);
> nd->account_pages = 0;
> }
> +
> + if (nd->zc_report && (nd->zc_copied || !nd->zc_used))
> + notif->cqe.res |= IORING_NOTIF_USAGE_ZC_COPIED;
> +
> io_req_task_complete(notif, locked);
> }
>
> @@ -28,6 +32,13 @@ static void io_uring_tx_zerocopy_callback(struct sk_buff *skb,
> struct io_notif_data *nd = container_of(uarg, struct io_notif_data, uarg);
> struct io_kiocb *notif = cmd_to_io_kiocb(nd);
>
> + if (nd->zc_report) {
> + if (success && !nd->zc_used && skb)
> + WRITE_ONCE(nd->zc_used, true);
> + else if (!success && !nd->zc_copied)
> + WRITE_ONCE(nd->zc_copied, true);
> + }
> +
> if (refcount_dec_and_test(&uarg->refcnt)) {
> notif->io_task_work.func = __io_notif_complete_tw;
> io_req_task_work_add(notif);
> @@ -55,6 +66,7 @@ struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx)
> nd->account_pages = 0;
> nd->uarg.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
> nd->uarg.callback = io_uring_tx_zerocopy_callback;
> + nd->zc_report = nd->zc_used = nd->zc_copied = false;
> refcount_set(&nd->uarg.refcnt, 1);
> return notif;
> }
> diff --git a/io_uring/notif.h b/io_uring/notif.h
> index 5b4d710c8ca5..4ae696273c78 100644
> --- a/io_uring/notif.h
> +++ b/io_uring/notif.h
> @@ -13,6 +13,9 @@ struct io_notif_data {
> struct file *file;
> struct ubuf_info uarg;
> unsigned long account_pages;
> + bool zc_report;
> + bool zc_used;
> + bool zc_copied;
> };
>
> void io_notif_flush(struct io_kiocb *notif);
--
Pavel Begunkov
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/1] io_uring/net: introduce IORING_SEND_ZC_REPORT_USAGE flag
2022-10-27 18:34 ` [PATCH 1/1] io_uring/net: introduce IORING_SEND_ZC_REPORT_USAGE flag Stefan Metzmacher
2022-10-28 13:12 ` Pavel Begunkov
2022-11-02 12:33 ` Pavel Begunkov
@ 2022-11-02 14:02 ` Jens Axboe
2 siblings, 0 replies; 4+ messages in thread
From: Jens Axboe @ 2022-11-02 14:02 UTC (permalink / raw)
To: Stefan Metzmacher, io-uring; +Cc: Pavel Begunkov
On Thu, 27 Oct 2022 20:34:45 +0200, Stefan Metzmacher wrote:
> It might be useful for applications to detect if a zero copy
> transfer with SEND[MSG]_ZC was actually possible or not.
> The application can fallback to plain SEND[MSG] in order
> to avoid the overhead of two cqes per request.
> Or it can generate a log message that could indicate
> to an administrator that no zero copy was possible
> and could explain degraded performance.
>
> [...]
Applied, thanks!
[1/1] io_uring/net: introduce IORING_SEND_ZC_REPORT_USAGE flag
commit: 4847a0eae62976ac27f192cd59b9de72b390eff3
Best regards,
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread