From e307e6698165ca6508ed42c69cb1be76c8eb6a3c Mon Sep 17 00:00:00 2001 From: Stefan Metzmacher Date: Thu, 27 Oct 2022 20:34:45 +0200 Subject: io_uring/net: introduce IORING_SEND_ZC_REPORT_USAGE flag 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. Cc: stable@vger.kernel.org # 6.1 Link: https://lore.kernel.org/io-uring/fb6a7599-8a9b-15e5-9b64-6cd9d01c6ff4@gmail.com/T/#m2b0d9df94ce43b0e69e6c089bdff0ce6babbdfaa Signed-off-by: Stefan Metzmacher Reviewed-by: Pavel Begunkov Link: https://lore.kernel.org/r/8945b01756d902f5d5b0667f20b957ad3f742e5e.1666895626.git.metze@samba.org Signed-off-by: Jens Axboe --- io_uring/net.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'io_uring/net.c') diff --git a/io_uring/net.c b/io_uring/net.c index ab83da7e80f0..03825b043afe 100644 --- a/io_uring/net.c +++ b/io_uring/net.c @@ -937,7 +937,8 @@ 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) @@ -955,6 +956,9 @@ 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])) -- cgit v1.2.3