From patchwork Mon Feb 8 18:55:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Willem de Bruijn X-Patchwork-Id: 379896 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F6B3C433E6 for ; Mon, 8 Feb 2021 18:59:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0235564E84 for ; Mon, 8 Feb 2021 18:59:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236008AbhBHS7d (ORCPT ); Mon, 8 Feb 2021 13:59:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235875AbhBHS5V (ORCPT ); Mon, 8 Feb 2021 13:57:21 -0500 Received: from mail-qk1-x735.google.com (mail-qk1-x735.google.com [IPv6:2607:f8b0:4864:20::735]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E06DC0617A7 for ; Mon, 8 Feb 2021 10:56:07 -0800 (PST) Received: by mail-qk1-x735.google.com with SMTP id l27so15474420qki.9 for ; Mon, 08 Feb 2021 10:56:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=V5SXxqRn9iChNkelA4Lz5t2Lq5FsheIFJl6lMmqNafs=; b=k1RlK0+rIiwKwfG+r9ciIyMYKAWET+IcMxexNzwQ+6z4uvYmVm0UL9tmzMKzLCn0r5 MENfN1EXiEQTscopjRumoVdOW1lKWWj4fEVTwe2Hqrf9FD08Cp6diJio+rxvIxngxUCC m6pes9Awe+fNvUqENRRffwYQHGecfMZ4Qmn46xJvm+oFVCGJrZlnfHj9RLogA5D0ZQEz onLIh5gMZg5ENRcaSB5EcFMY0OIoMLlmgFhBl8NWczXYnHyCNPfiARsRf1wlTIXDs1rt CYuyUQgOa2xHtTfCgnCzjNDo1hiiLpBXscWeJQV5KOrUgPLho2xqhVhXRizC9D+VJMma cJYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=V5SXxqRn9iChNkelA4Lz5t2Lq5FsheIFJl6lMmqNafs=; b=Vo4Sph7PmKvsqJdN8O3HT37XEDm/B9giDTUrHMqc0ZAiK65Jee3dzhkkedCCBi2Pwb sXJL2XuZP/kIlZF0wfv7rW/v0AM/xFYjcfI3kJgBCrHn1wqlMG+dtCQuSahV9Ll/IX+X Puy1iY48P4YmOs5wC72fOGy8v8IaUFUZTp6dd60RkIKLyP2lUMbfmaey7552y9Pb2u7A 12RQ9zLruwI+iYXvD96ftxap4S/px2z0YPnBRkdx3TkxlgFmssL8iIgGFECGlK2fxeOg HL27YM+BbOchebqJoKVtkt+88TzBJFoI6iS+WA3P0nRX7eWrqc5ysouFfkAXjgTTlFmd cgDg== X-Gm-Message-State: AOAM533SJZ9UrRrEWG+8cHxzafu2FFpub6KyxZMN2Rx0Pn9UXbSgldkH bqp6yL7CeQVoxrb9GuTvh0+VN6dFVBQ= X-Google-Smtp-Source: ABdhPJx2Vzz3BN3fufrvFs0gfLszLO304XiNcsw2UEPhzqYAxQtPHMyuALjvbbug6pZAp9GoEaItqw== X-Received: by 2002:a05:620a:8dc:: with SMTP id z28mr1023748qkz.404.1612810566558; Mon, 08 Feb 2021 10:56:06 -0800 (PST) Received: from willemb.nyc.corp.google.com ([2620:0:1003:312:f109:45d3:805f:3b83]) by smtp.gmail.com with ESMTPSA id q25sm17370744qkq.32.2021.02.08.10.56.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Feb 2021 10:56:05 -0800 (PST) From: Willem de Bruijn To: virtualization@lists.linux-foundation.org Cc: netdev@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, richardcochran@gmail.com, Willem de Bruijn Subject: [PATCH RFC v2 4/4] virtio-net: support future packet transmit time Date: Mon, 8 Feb 2021 13:55:58 -0500 Message-Id: <20210208185558.995292-5-willemdebruijn.kernel@gmail.com> X-Mailer: git-send-email 2.30.0.478.g8a0d178c01-goog In-Reply-To: <20210208185558.995292-1-willemdebruijn.kernel@gmail.com> References: <20210208185558.995292-1-willemdebruijn.kernel@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Willem de Bruijn Add optional transmit time (SO_TXTIME) offload for virtio-net. The Linux TCP/IP stack tries to avoid bursty transmission and network congestion through pacing: computing an skb delivery time based on congestion information. Userspace protocol implementations can achieve the same with SO_TXTIME. This may also reduce scheduling jitter and improve RTT estimation. Pacing can be implemented in ETF or FQ qdiscs or offloaded to NIC hardware. Allow virtio-net driver to offload for the same reasons. The timestamp straddles (virtual) hardware domains. Like PTP, use international atomic time (CLOCK_TAI) as global clock base. The driver must sync with the device, e.g., through kvm-clock. Changes RFC - RFCv2 - rename from transmit timestamp to future packet transmit time - convert cpu_to_virtioXX to cpu_to_leXX Signed-off-by: Willem de Bruijn --- drivers/net/virtio_net.c | 13 ++++++++++++- include/uapi/linux/virtio_net.h | 1 + 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index fc8ecd3a333a..c09d19b97f42 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -216,6 +216,9 @@ struct virtnet_info { /* Device will pass tx timestamp. Requires has_tx_tstamp */ bool enable_tx_tstamp; + /* Driver will pass CLOCK_TAI delivery time to the device */ + bool has_tx_time; + /* Has control virtqueue */ bool has_cvq; @@ -1616,6 +1619,8 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb) } if (vi->enable_tx_tstamp && skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) ht->hdr.flags |= VIRTIO_NET_HDR_F_TSTAMP; + if (vi->has_tx_time && skb->tstamp) + ht->tstamp = cpu_to_le64(skb->tstamp); sg_init_table(sq->sg, skb_shinfo(skb)->nr_frags + (can_push ? 1 : 2)); if (can_push) { @@ -3221,6 +3226,11 @@ static int virtnet_probe(struct virtio_device *vdev) vi->hdr_len = sizeof(struct virtio_net_hdr_hash_ts); } + if (virtio_has_feature(vdev, VIRTIO_NET_F_TX_TIME)) { + vi->has_tx_time = true; + vi->hdr_len = sizeof(struct virtio_net_hdr_hash_ts); + } + if (virtio_has_feature(vdev, VIRTIO_F_ANY_LAYOUT) || virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) vi->any_header_sg = true; @@ -3412,7 +3422,8 @@ static struct virtio_device_id id_table[] = { VIRTIO_NET_F_CTRL_MAC_ADDR, \ VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \ VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY, \ - VIRTIO_NET_F_TX_HASH, VIRTIO_NET_F_RX_TSTAMP, VIRTIO_NET_F_TX_TSTAMP + VIRTIO_NET_F_TX_HASH, VIRTIO_NET_F_RX_TSTAMP, VIRTIO_NET_F_TX_TSTAMP, \ + VIRTIO_NET_F_TX_TIME static unsigned int features[] = { VIRTNET_FEATURES, diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h index b5d6f0c6cead..7ca99a2ee1a3 100644 --- a/include/uapi/linux/virtio_net.h +++ b/include/uapi/linux/virtio_net.h @@ -57,6 +57,7 @@ * Steering */ #define VIRTIO_NET_F_CTRL_MAC_ADDR 23 /* Set MAC address */ +#define VIRTIO_NET_F_TX_TIME 53 /* Driver sets TAI delivery time */ #define VIRTIO_NET_F_TX_TSTAMP 54 /* Device sends TAI transmit time */ #define VIRTIO_NET_F_RX_TSTAMP 55 /* Device sends TAI receive time */ #define VIRTIO_NET_F_TX_HASH 56 /* Driver sends hash report */