From nobody Sat Jul 25 15:53:53 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1784209494; cv=none; d=zohomail.com; s=zohoarc; b=Ihm3ZEg+zt9wLfRt/w+1nS20ziwVuJFemjOlsswOq2Lez3CWY33h/JGyGM3rxv3c1+fth6tn1j8wp5cJbVQQZjSZaW2HaLFAAiQgckAXGp2p4yUSHEfEiSFNnc618ZjFmTsRVXd/O5bGG10mvWNqWdXSuR4YdBmYN3O5FMsQX4E= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1784209494; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=Qd3TNrOnqY8L2J6lvZ814YmXt5L8tWJW+CCI1BK2UIw=; b=IIGKrSxA9gEDQDsrSTAD+gCIC8ITpydsBUNacszPdpH16yb/1CszcSUQ6hj1lfKvF2L+Qpa9eLpUVUX+GIjAQi+mCkt3ScAIscwAmE3qO/AngsGKIB8D9wCqj4YvwUMX1hHFA9biE2eTkvx3lSI5iIMyNV9x7V31pWB0pA0xX+k= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1784209494296945.1716232891425; Thu, 16 Jul 2026 06:44:54 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wkMOG-0002UU-QX; Thu, 16 Jul 2026 09:44:40 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wkMOE-0002U3-Uc for qemu-devel@nongnu.org; Thu, 16 Jul 2026 09:44:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wkMOC-0007N0-Us for qemu-devel@nongnu.org; Thu, 16 Jul 2026 09:44:38 -0400 Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-530-QmfjZb8YORyZyHSQetUFog-1; Thu, 16 Jul 2026 09:44:32 -0400 Received: from mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.95]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C16C41955F31; Thu, 16 Jul 2026 13:44:31 +0000 (UTC) Received: from kdutta-thinkpadp1gen7.bengluru.csb (unknown [10.74.80.216]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id D34EA42E; Thu, 16 Jul 2026 13:44:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1784209476; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Qd3TNrOnqY8L2J6lvZ814YmXt5L8tWJW+CCI1BK2UIw=; b=KsfFLyKgXg2Az6BtA40Rq6HVq4AG9jyCfDvAhUjC4mQQa7WN06TX5151dF7hkjePcSTXMC FW0JHvmWjEolZNKR5J0NNn3rOOvz74GYEE9ZildwrznbMkslnBIiUNPNDTEFQ1IpykSz1j 7iJPuTUuXd9ciDJ70nHBqKDaUlb3EIQ= X-MC-Unique: QmfjZb8YORyZyHSQetUFog-1 X-Mimecast-MFC-AGG-ID: QmfjZb8YORyZyHSQetUFog_1784209472 From: Koushik Dutta To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Eugenio=20P=C3=A9rez?= , "Michael S. Tsirkin" , Stefano Garzarella , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Zhao Liu , Jason Wang Subject: [PATCH v10 1/2] [PATCH 1/2] Introduce virtio_net_handle_tx_dispatch() to unify TX path handling. This dispatcher dynamically selects between timer-based and BH-based TX processing based on configuration. Date: Thu, 16 Jul 2026 19:14:20 +0530 Message-ID: <20260716134421.3765533-2-kdutta@redhat.com> In-Reply-To: <20260716134421.3765533-1-kdutta@redhat.com> References: <20260716134421.3765533-1-kdutta@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: permerror client-ip=170.10.133.124; envelope-from=kdutta@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, T_SPF_PERMERROR=0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1784209496543158500 Content-Type: text/plain; charset="utf-8" Previously, the tx=3Dtimer selected between two completely separate code paths at queue creation time. This refactoring introduces a runtime dispatch mechanism while maintaining identical behavior. This is a preparatory patch with no functional changes, making it easier to add dynamic TX notification coalescing in a subsequent patch. Signed-off-by: Koushik Dutta --- hw/net/virtio-net.c | 41 ++++++++++++++++++++++------------ include/hw/virtio/virtio-net.h | 1 + 2 files changed, 28 insertions(+), 14 deletions(-) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 2a5d642a64..e7f05956a5 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -2973,6 +2973,22 @@ static void virtio_net_tx_bh(void *opaque) } } =20 +static void virtio_net_handle_tx_dispatch(VirtIODevice *vdev, VirtQueue *v= q) +{ + VirtIONet *n =3D VIRTIO_NET(vdev); + VirtIONetQueue *q =3D &n->vqs[vq2q(virtio_get_queue_index(vq))]; + + if (n->tx_timer_activate) { + if (q->tx_timer =3D=3D NULL) { + q->tx_timer =3D timer_new_ns(QEMU_CLOCK_VIRTUAL, + virtio_net_tx_timer, q); + } + virtio_net_handle_tx_timer(vdev, vq); + } else { + virtio_net_handle_tx_bh(vdev, vq); + } +} + static void virtio_net_add_queue(VirtIONet *n, int index) { VirtIODevice *vdev =3D VIRTIO_DEVICE(n); @@ -2980,20 +2996,13 @@ static void virtio_net_add_queue(VirtIONet *n, int = index) n->vqs[index].rx_vq =3D virtio_add_queue(vdev, n->net_conf.rx_queue_si= ze, virtio_net_handle_rx); =20 - if (n->net_conf.tx && !strcmp(n->net_conf.tx, "timer")) { - n->vqs[index].tx_vq =3D - virtio_add_queue(vdev, n->net_conf.tx_queue_size, - virtio_net_handle_tx_timer); - n->vqs[index].tx_timer =3D timer_new_ns(QEMU_CLOCK_VIRTUAL, - virtio_net_tx_timer, - &n->vqs[index]); - } else { - n->vqs[index].tx_vq =3D - virtio_add_queue(vdev, n->net_conf.tx_queue_size, - virtio_net_handle_tx_bh); - n->vqs[index].tx_bh =3D qemu_bh_new_guarded(virtio_net_tx_bh, &n->= vqs[index], - &DEVICE(vdev)->mem_reent= rancy_guard); - } + n->vqs[index].tx_vq =3D + virtio_add_queue(vdev, n->net_conf.tx_queue_size, + virtio_net_handle_tx_dispatch); + + n->vqs[index].tx_bh =3D + qemu_bh_new_guarded(virtio_net_tx_bh, &n->vqs[index], + &DEVICE(vdev)->mem_reentrancy_guard); =20 n->vqs[index].tx_waiting =3D 0; n->vqs[index].n =3D n; @@ -3970,6 +3979,10 @@ static void virtio_net_device_realize(DeviceState *d= ev, Error **errp) error_printf("Defaulting to \"bh\""); } =20 + if (n->net_conf.tx && strcmp(n->net_conf.tx, "timer") =3D=3D 0) { + n->tx_timer_activate =3D true; + } + n->net_conf.tx_queue_size =3D MIN(virtio_net_max_tx_queue_size(n), n->net_conf.tx_queue_size); =20 diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h index 371e376428..a4eb3f407e 100644 --- a/include/hw/virtio/virtio-net.h +++ b/include/hw/virtio/virtio-net.h @@ -230,6 +230,7 @@ struct VirtIONet { struct EBPFRSSContext ebpf_rss; uint32_t nr_ebpf_rss_fds; char **ebpf_rss_fds; + bool tx_timer_activate; }; =20 size_t virtio_net_handle_ctrl_iov(VirtIODevice *vdev, --=20 2.53.0 From nobody Sat Jul 25 15:53:53 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1784209510; cv=none; d=zohomail.com; s=zohoarc; b=jtIAwd7GPgyy17572KdwsI0u/jkL3khSYeIo7NxyTEmjsfqWoawkupBeYdX0zD4WYEpmnm7HHHwNnry2c8XRLn3DK5H4PUroVbUAhz/vIAOS5KI7aoSlHVu9UmyeVMS18aSVHmAjgK9gm3+A0wzGwKLlLIaZdN9o2p3f563+YTw= ARC-Message-Signature: i=1; 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Thu, 16 Jul 2026 13:44:35 +0000 (UTC) Received: from kdutta-thinkpadp1gen7.bengluru.csb (unknown [10.74.80.216]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6EB0A42E; Thu, 16 Jul 2026 13:44:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1784209482; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=bGprAAMhsBLm/djvyAE64mSKdfRYnPPY8PLAUIwi0ck=; b=UNG9ck820cIWZSkDsMwqSp+m/OwcImtMzZ8Xv+DoGyTSWh+nNJnBWUBYH4BgCixJ4l8mCt HeZEbipTyzqSmP0hsqaQ43dHAiCqEt+LPt9bvDMQMzk9by/S2YYYUZDt31P9rHIzw9EcuI gvL/C/2pAroN/ATz7mBFgn3SZ7ql32M= X-MC-Unique: -WmaCfzSOZu347vAmeEKFw-1 X-Mimecast-MFC-AGG-ID: -WmaCfzSOZu347vAmeEKFw_1784209475 From: Koushik Dutta To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Eugenio=20P=C3=A9rez?= , "Michael S. Tsirkin" , Stefano Garzarella , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Zhao Liu , Jason Wang Subject: [PATCH v10 2/2] [PATCH 2/2] Implement VirtIO Network Notification Coalescing (VIRTIO_NET_F_NOTF_COAL). This allows guests to reduce interrupt overhead by configuring coalescing parameters via ethtool -C for both RX and TX paths. Date: Thu, 16 Jul 2026 19:14:21 +0530 Message-ID: <20260716134421.3765533-3-kdutta@redhat.com> In-Reply-To: <20260716134421.3765533-1-kdutta@redhat.com> References: <20260716134421.3765533-1-kdutta@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: permerror client-ip=170.10.129.124; envelope-from=kdutta@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.01, SPF_HELO_PASS=-0.001, T_SPF_PERMERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1784209512415158500 The feature supports two coalescing modes: - Time-based: delay notifications up to N microseconds - Count-based: delay until N packets are processed Implementation details: - Added VIRTIO_NET_CTRL_NOTF_COAL class handling in control virtqueue - RX path: batches notifications based on packet count or timeout - TX path: leverages the unified dispatcher to dynamically enable timer-based coalescing when guest configures it via ethtool - Coalescing parameters persist across live migration Note: When tx=3Dtimer is configured at VM launch, the coalescing feature is automatically disabled because tx=3Dtimer already introduces a fixed 150=C2=B5s delay for packet batching, making notification coalescing redund= ant. Adds the `x-vq_notf_coal=3Don` device parameter to dynamically enable virtqueue notification coalescing at VM startup. Performance metrics (Moderate Coalescing vs Without Coalescing): - RX parameters: 1000=C2=B5s, 10 frames - TX parameters: 2000=C2=B5s, 20 frames - Results: 20% drop in CPU overhead and a 30% reduction in interrupts. Signed-off-by: Koushik Dutta --- hw/net/virtio-net.c | 203 ++++++++++++++++++++++++++++++++- include/hw/virtio/virtio-net.h | 10 ++ net/passt.c | 1 + net/tap.c | 1 + net/vhost-user.c | 1 + net/vhost-vdpa.c | 1 + 6 files changed, 213 insertions(+), 4 deletions(-) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index e7f05956a5..fac1013d47 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -157,6 +157,16 @@ static void flush_or_purge_queued_packets(NetClientSta= te *nc) * - we could suppress RX interrupt if we were so inclined. */ =20 +static void virtio_net_rx_notify(void *opaque) +{ + VirtIONetQueue *q =3D opaque; + VirtIONet *n =3D q->n; + VirtIODevice *vdev =3D VIRTIO_DEVICE(n); + + q->rx_coal.pkt_cnt =3D 0; + virtio_notify(vdev, q->rx_vq); +} + static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config) { VirtIONet *n =3D VIRTIO_NET(vdev); @@ -1002,6 +1012,87 @@ static void virtio_net_set_features(VirtIODevice *vd= ev, } } =20 +static void virtio_net_tx_notification_timer(void *opaque) +{ + VirtIONetQueue *q =3D opaque; + VirtIONet *n =3D q->n; + VirtIODevice *vdev =3D VIRTIO_DEVICE(n); + + q->tx_coal.pkt_cnt =3D 0; + virtio_notify(vdev, q->tx_vq); +} + +static bool virtio_net_tx_should_notify(VirtIONetQueue *q) +{ + if (q->tx_coal.usecs =3D=3D 0 || !q->tx_coal.timer) { + return true; + } + + q->tx_coal.pkt_cnt++; + + if (q->tx_coal.packets > 0 && q->tx_coal.pkt_cnt >=3D q->tx_coal.packe= ts) { + q->tx_coal.pkt_cnt =3D 0; + timer_del(q->tx_coal.timer); + return true; + } + + if (!timer_pending(q->tx_coal.timer)) { + timer_mod(q->tx_coal.timer, + qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + + q->tx_coal.usecs * 1000); /* Converted to ns */ + } + + return false; +} + +static int virtio_net_handle_coal(VirtIONet *n, uint8_t cmd, + struct iovec *iov, unsigned int iov_cnt) +{ + struct virtio_net_ctrl_coal coal; + VirtIONetQueue *q; + size_t s; + int i; + + s =3D iov_to_buf(iov, iov_cnt, 0, &coal, sizeof(coal)); + if (s !=3D sizeof(coal)) { + return VIRTIO_NET_ERR; + } + + if (cmd =3D=3D VIRTIO_NET_CTRL_NOTF_COAL_RX_SET) { + for (i =3D 0; i < n->max_queue_pairs; i++) { + q =3D &n->vqs[i]; + q->rx_coal.usecs =3D le32_to_cpu(coal.max_usecs); + q->rx_coal.packets =3D le32_to_cpu(coal.max_packets); + q->rx_coal.pkt_cnt =3D 0; + if (q->rx_coal.usecs > 0) { + /* Delete old timer if exists, then create new one */ + g_clear_pointer(&q->rx_coal.timer, timer_free); + q->rx_coal.timer =3D timer_new_ns(QEMU_CLOCK_VIRTUAL, + virtio_net_rx_notify, + q); + } else { + g_clear_pointer(&q->rx_coal.timer, timer_free); + } + } + } else if (cmd =3D=3D VIRTIO_NET_CTRL_NOTF_COAL_TX_SET) { + for (i =3D 0; i < n->max_queue_pairs; i++) { + q =3D &n->vqs[i]; + q->tx_coal.usecs =3D le32_to_cpu(coal.max_usecs); + q->tx_coal.packets =3D le32_to_cpu(coal.max_packets); + q->tx_coal.pkt_cnt =3D 0; + if (q->tx_coal.usecs > 0) { + g_clear_pointer(&q->tx_coal.timer, timer_free); + q->tx_coal.timer =3D timer_new_ns(QEMU_CLOCK_VIRTUAL, + virtio_net_tx_notification= _timer, + q); + } else { + g_clear_pointer(&q->tx_coal.timer, timer_free); + } + } + } + return VIRTIO_NET_OK; +} + static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd, struct iovec *iov, unsigned int iov_c= nt) { @@ -1581,6 +1672,8 @@ size_t virtio_net_handle_ctrl_iov(VirtIODevice *vdev, status =3D virtio_net_handle_mq(n, ctrl.cmd, iov, out_num); } else if (ctrl.class =3D=3D VIRTIO_NET_CTRL_GUEST_OFFLOADS) { status =3D virtio_net_handle_offloads(n, ctrl.cmd, iov, out_num); + } else if (ctrl.class =3D=3D VIRTIO_NET_CTRL_NOTF_COAL) { + status =3D virtio_net_handle_coal(n, ctrl.cmd, iov, out_num); } =20 s =3D iov_from_buf(in_sg, in_num, 0, &status, sizeof(status)); @@ -2040,7 +2133,23 @@ static ssize_t virtio_net_receive_rcu(NetClientState= *nc, const uint8_t *buf, } =20 virtqueue_flush(q->rx_vq, i); - virtio_notify(vdev, q->rx_vq); + + /* rx coalescing */ + q->rx_coal.pkt_cnt +=3D i; + if (q->rx_coal.usecs =3D=3D 0 || q->rx_coal.pkt_cnt >=3D q->rx_coal.pa= ckets) { + if (q->rx_coal.timer) { + timer_del(q->rx_coal.timer); + } + virtio_net_rx_notify(q); + } else { + if (q->rx_coal.timer) { + if (!timer_pending(q->rx_coal.timer)) { + timer_mod(q->rx_coal.timer, + qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + + q->rx_coal.usecs * 1000); /* Converted to ns */ + } + } + } =20 return size; =20 @@ -2690,7 +2799,9 @@ static void virtio_net_tx_complete(NetClientState *nc= , ssize_t len) int ret; =20 virtqueue_push(q->tx_vq, q->async_tx.elem, 0); - virtio_notify(vdev, q->tx_vq); + if (virtio_net_tx_should_notify(q)) { + virtio_notify(vdev, q->tx_vq); + } =20 g_free(q->async_tx.elem); q->async_tx.elem =3D NULL; @@ -2802,7 +2913,10 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) =20 drop: virtqueue_push(q->tx_vq, elem, 0); - virtio_notify(vdev, q->tx_vq); + if (virtio_net_tx_should_notify(q)) { + virtio_notify(vdev, q->tx_vq); + } + g_free(elem); =20 if (++num_packets >=3D n->tx_burst) { @@ -2899,6 +3013,7 @@ static void virtio_net_tx_timer(void *opaque) if (ret =3D=3D -EBUSY || ret =3D=3D -EINVAL) { return; } + /* * If we flush a full burst of packets, assume there are * more coming and immediately rearm @@ -3005,6 +3120,12 @@ static void virtio_net_add_queue(VirtIONet *n, int i= ndex) &DEVICE(vdev)->mem_reentrancy_guard); =20 n->vqs[index].tx_waiting =3D 0; + n->vqs[index].rx_coal.pkt_cnt =3D 0; + n->vqs[index].tx_coal.pkt_cnt =3D 0; + n->vqs[index].rx_coal.usecs =3D 0; + n->vqs[index].tx_coal.usecs =3D 0; + n->vqs[index].rx_coal.packets =3D 0; + n->vqs[index].tx_coal.packets =3D 0; n->vqs[index].n =3D n; } =20 @@ -3017,6 +3138,11 @@ static void virtio_net_del_queue(VirtIONet *n, int i= ndex) qemu_purge_queued_packets(nc); =20 virtio_del_queue(vdev, index * 2); + + /* Cleanup coalescing timers */ + g_clear_pointer(&q->rx_coal.timer, timer_free); + g_clear_pointer(&q->tx_coal.timer, timer_free); + if (q->tx_timer) { timer_free(q->tx_timer); q->tx_timer =3D NULL; @@ -3097,6 +3223,13 @@ static void virtio_net_get_features(VirtIODevice *vd= ev, uint64_t *features, virtio_features_or(features, features, n->host_features_ex); =20 virtio_add_feature_ex(features, VIRTIO_NET_F_MAC); + if (n->tx_timer_activate) { + virtio_clear_feature_ex(features, VIRTIO_NET_F_NOTF_COAL); + } else { + if (!virtio_has_feature(*features, VIRTIO_NET_F_NOTF_COAL)) { + *features &=3D ~(1ULL << VIRTIO_NET_F_NOTF_COAL); + } + } =20 if (!peer_has_vnet_hdr(n)) { virtio_clear_feature_ex(features, VIRTIO_NET_F_CSUM); @@ -3251,6 +3384,26 @@ static int virtio_net_post_load_device(void *opaque,= int version_id) } =20 virtio_net_commit_rss_config(n); + + for (i =3D 0; i < n->max_queue_pairs; i++) { + VirtIONetQueue *q =3D &n->vqs[i]; + if (q->rx_coal.usecs > 0) { + if (!q->rx_coal.timer) { + q->rx_coal.timer =3D timer_new_ns(QEMU_CLOCK_VIRTUAL, + virtio_net_rx_notify, + q); + } + } + + if (q->tx_coal.usecs > 0) { + if (!q->tx_coal.timer) { + q->tx_coal.timer =3D timer_new_ns(QEMU_CLOCK_VIRTUAL, + virtio_net_tx_notification= _timer, + q); + } + } + } + return 0; } =20 @@ -3270,13 +3423,49 @@ static int virtio_net_post_load_virtio(VirtIODevice= *vdev) return 0; } =20 +static const VMStateDescription vmstate_virtio_net_coal =3D { + .name =3D "virtio-net-coal", + .version_id =3D 1, + .minimum_version_id =3D 1, + .fields =3D (const VMStateField[]) { + VMSTATE_UINT32(usecs, VirtIONetCoal), + VMSTATE_UINT32(packets, VirtIONetCoal), + VMSTATE_UINT32(pkt_cnt, VirtIONetCoal), + VMSTATE_END_OF_LIST() + }, +}; + +static bool virtio_net_queue_notf_coal_needed(void *opaque) +{ + VirtIONetQueue *q =3D opaque; + return q->rx_coal.usecs > 0 || q->tx_coal.usecs > 0; +} + +static const VMStateDescription vmstate_virtio_net_queue_notf_coal =3D { + .name =3D "virtio-net-queue-tx_waiting/notf-coal", + .version_id =3D 1, + .minimum_version_id =3D 1, + .needed =3D virtio_net_queue_notf_coal_needed, + .fields =3D (const VMStateField[]) { + VMSTATE_STRUCT(rx_coal, VirtIONetQueue, 0, + vmstate_virtio_net_coal, VirtIONetCoal), + VMSTATE_STRUCT(tx_coal, VirtIONetQueue, 0, + vmstate_virtio_net_coal, VirtIONetCoal), + VMSTATE_END_OF_LIST() + }, +}; + /* tx_waiting field of a VirtIONetQueue */ static const VMStateDescription vmstate_virtio_net_queue_tx_waiting =3D { .name =3D "virtio-net-queue-tx_waiting", .fields =3D (const VMStateField[]) { VMSTATE_UINT32(tx_waiting, VirtIONetQueue), VMSTATE_END_OF_LIST() - }, + }, + .subsections =3D (const VMStateDescription * const []) { + &vmstate_virtio_net_queue_notf_coal, + NULL + } }; =20 static bool max_queue_pairs_gt_1(void *opaque, int version_id) @@ -3981,6 +4170,10 @@ static void virtio_net_device_realize(DeviceState *d= ev, Error **errp) =20 if (n->net_conf.tx && strcmp(n->net_conf.tx, "timer") =3D=3D 0) { n->tx_timer_activate =3D true; + if (n->host_features & (1ULL << VIRTIO_NET_F_NOTF_COAL)) { + warn_report("virtio-net: 'vq_notf_coal' is incompatible with '= tx=3Dtimer'," + "disabling notification coalescing"); + } } =20 n->net_conf.tx_queue_size =3D MIN(virtio_net_max_tx_queue_size(n), @@ -4271,6 +4464,8 @@ static const Property virtio_net_properties[] =3D { VIRTIO_NET_F_GUEST_USO6, true), DEFINE_PROP_BIT64("host_uso", VirtIONet, host_features, VIRTIO_NET_F_HOST_USO, true), + DEFINE_PROP_BIT64("x-vq_notf_coal", VirtIONet, host_features, + VIRTIO_NET_F_NOTF_COAL, false), DEFINE_PROP_ON_OFF_AUTO_BIT64("hash-ipv4", VirtIONet, rss_data.specified_hash_types, VIRTIO_NET_HASH_REPORT_IPv4 - 1, diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h index a4eb3f407e..244c8a0224 100644 --- a/include/hw/virtio/virtio-net.h +++ b/include/hw/virtio/virtio-net.h @@ -155,6 +155,14 @@ typedef struct VirtioNetRssData { uint16_t default_queue; } VirtioNetRssData; =20 +/* Interrupt notification coalescing parameters */ +typedef struct VirtIONetCoal { + uint32_t usecs; /* Timeout in microseconds */ + uint32_t packets; /* Packet count threshold */ + uint32_t pkt_cnt; /* Current packet count since last notification */ + QEMUTimer *timer; /* Coalescing timer */ +} VirtIONetCoal; + typedef struct VirtIONetQueue { VirtQueue *rx_vq; VirtQueue *tx_vq; @@ -165,6 +173,8 @@ typedef struct VirtIONetQueue { VirtQueueElement *elem; } async_tx; struct VirtIONet *n; + VirtIONetCoal rx_coal; + VirtIONetCoal tx_coal; } VirtIONetQueue; =20 struct VirtIONet { diff --git a/net/passt.c b/net/passt.c index 45440c399b..43b36ed8c5 100644 --- a/net/passt.c +++ b/net/passt.c @@ -52,6 +52,7 @@ static const int user_feature_bits[] =3D { VIRTIO_NET_F_GUEST_USO4, VIRTIO_NET_F_GUEST_USO6, VIRTIO_NET_F_HOST_USO, + VIRTIO_NET_F_NOTF_COAL, =20 /* This bit implies RARP isn't sent by QEMU out of band */ VIRTIO_NET_F_GUEST_ANNOUNCE, diff --git a/net/tap.c b/net/tap.c index 57ffb09885..e6ddbc1eb1 100644 --- a/net/tap.c +++ b/net/tap.c @@ -63,6 +63,7 @@ static const int kernel_feature_bits[] =3D { VIRTIO_F_NOTIFICATION_DATA, VIRTIO_NET_F_RSC_EXT, VIRTIO_NET_F_HASH_REPORT, + VIRTIO_NET_F_NOTF_COAL, VIRTIO_NET_F_GUEST_UDP_TUNNEL_GSO, VIRTIO_NET_F_HOST_UDP_TUNNEL_GSO, VHOST_INVALID_FEATURE_BIT diff --git a/net/vhost-user.c b/net/vhost-user.c index 2d0fc49b4d..f1e9b7a038 100644 --- a/net/vhost-user.c +++ b/net/vhost-user.c @@ -54,6 +54,7 @@ static const int user_feature_bits[] =3D { VIRTIO_NET_F_GUEST_USO4, VIRTIO_NET_F_GUEST_USO6, VIRTIO_NET_F_HOST_USO, + VIRTIO_NET_F_NOTF_COAL, =20 /* This bit implies RARP isn't sent by QEMU out of band */ VIRTIO_NET_F_GUEST_ANNOUNCE, diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c index f1523697e2..0dcd6fb9f1 100644 --- a/net/vhost-vdpa.c +++ b/net/vhost-vdpa.c @@ -70,6 +70,7 @@ static const int vdpa_feature_bits[] =3D { VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_RX_EXTRA, VIRTIO_NET_F_CTRL_VLAN, + VIRTIO_NET_F_NOTF_COAL, VIRTIO_NET_F_CTRL_VQ, VIRTIO_NET_F_GSO, VIRTIO_NET_F_GUEST_CSUM, --=20 2.53.0