From patchwork Thu Jul 11 14:58:47 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luigi Leonardi via B4 Relay X-Patchwork-Id: 13730801 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D315416A959; Thu, 11 Jul 2024 14:58:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720709937; cv=none; b=Uo458HWKqXSGwumpvOvJP2inoRTM5u9OcX/tOyvsMLVxJP2QMG9x8wp+p4fzzY0x93Zd9YMnAgeFcHsfqE/EYQZpOwegp7zbaQmtavxRUox5kNL2a0zrCjTx9scuYjg676PcmjBfQY/snh/dT+qI7i9h5noAKROLbQMRun2AS+g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720709937; c=relaxed/simple; bh=qhrnhHTcxp4T6MXoVbfRMMZfLqgKWmxtfnbbImsicDY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=tkGFnqc4azG9WvZiolea9v9x/QJVf9cF/qJAHJN0T4tYRfy6/gWRFCHtFtvPkhxlonkn01L1JFIJ0Q4hTVh8tDYem+mBOjjNpStVdgujcKZ8dRs20ZiiaeOE7eD2UCRbFbBBBYTQ/dBWnuoNY6wFQsedkxlmwZCUifpOdqHCRDI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EILGikFH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EILGikFH" Received: by smtp.kernel.org (Postfix) with ESMTPS id 79549C4AF0A; Thu, 11 Jul 2024 14:58:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720709937; bh=qhrnhHTcxp4T6MXoVbfRMMZfLqgKWmxtfnbbImsicDY=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=EILGikFHho0uV8PyHBDvYj8ll2Dx6KH5IDLHaJ5k16Xx7ehSeHgGdtSf8QoGqRQyA JHVplMBNkQ8twokoVLpqsS+G/UFNnzQoWntH5AE+YPom10Y4V9buJNtMw+48kzmjjT 4DTz8zmDcttFPhSq1enoA0LWo2xEUY/aI/hnrD4p3J/07sb4561oePa0gUmiTRlXvz AmZ5nprwkDaHhx7P9NYk32DUxW6gD64UsXX7cM0/63lN1nHcKgQ77kcNFdqo752wfM 9g2lR46BKlMBDi8orEjegbe4AkxReuwLxLqXejkdXcXh/fjjCsVoYHp/YDVskUds5J VYxGFtpzRgg0A== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B72FC3DA4E; Thu, 11 Jul 2024 14:58:57 +0000 (UTC) From: Luigi Leonardi via B4 Relay Date: Thu, 11 Jul 2024 16:58:47 +0200 Subject: [PATCH net-next v3 2/2] vsock/virtio: avoid queuing packets when work queue is empty Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240711-pinna-v3-2-697d4164fe80@outlook.com> References: <20240711-pinna-v3-0-697d4164fe80@outlook.com> In-Reply-To: <20240711-pinna-v3-0-697d4164fe80@outlook.com> To: Stefan Hajnoczi , Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: kvm@vger.kernel.org, virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Luigi Leonardi , Marco Pinna X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1720709936; l=3561; i=luigi.leonardi@outlook.com; s=20240626; h=from:subject:message-id; bh=l638VLzyzZ3I1aI8lPsDMG/usnFXIqhwGjTbGe9Tv7I=; b=DR4Cm+5TRSB/dUyBv/HfqjrwXGSLbFkVIM5oXx/s8ziijZhYilonRc84awoQ+U23YVu9pQHPf Un0RHiSrG5+B3/ldGuqDzy1+BxdPcB9LRw442gLcooE8+RNs10fdufs X-Developer-Key: i=luigi.leonardi@outlook.com; a=ed25519; pk=RYXD8JyCxGnx/izNc/6b3g3pgpohJMAI0LJ7ynxXzi8= X-Endpoint-Received: by B4 Relay for luigi.leonardi@outlook.com/20240626 with auth_id=177 X-Original-From: Luigi Leonardi Reply-To: luigi.leonardi@outlook.com From: Luigi Leonardi Introduce an optimization in virtio_transport_send_pkt: when the work queue (send_pkt_queue) is empty the packet is put directly in the virtqueue increasing the throughput. In the following benchmark (pingpong mode) the host sends a payload to the guest and waits for the same payload back. All vCPUs pinned individually to pCPUs. vhost process pinned to a pCPU fio process pinned both inside the host and the guest system. Host CPU: Intel i7-10700KF CPU @ 3.80GHz Tool: Fio version 3.37-56 Env: Phys host + L1 Guest Runtime-per-test: 50s Mode: pingpong (h-g-h) Test runs: 50 Type: SOCK_STREAM Before: Linux 6.9.7 Payload 512B: 1st perc. overall 99th perc. Before 370 810.15 8656 ns After 374 780.29 8741 ns Payload 4K: 1st perc. overall 99th perc. Before 460 1720.23 42752 ns After 460 1520.84 36096 ns The performance improvement is related to this optimization, I used ebpf to check that each packet was sent directly to the virtqueue. Throughput: iperf-vsock The size represents the buffer length (-l) to read/write P represents the number parallel streams P=1 4K 64K 128K Before 6.87 29.3 29.5 Gb/s After 10.5 39.4 39.9 Gb/s P=2 4K 64K 128K Before 10.5 32.8 33.2 Gb/s After 17.8 47.7 48.5 Gb/s P=4 4K 64K 128K Before 12.7 33.6 34.2 Gb/s After 16.9 48.1 50.5 Gb/s Co-developed-by: Marco Pinna Signed-off-by: Marco Pinna Signed-off-by: Luigi Leonardi --- net/vmw_vsock/virtio_transport.c | 38 ++++++++++++++++++++++++++++++++++---- 1 file changed, 34 insertions(+), 4 deletions(-) diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c index c4205c22f40b..d75727fdc35f 100644 --- a/net/vmw_vsock/virtio_transport.c +++ b/net/vmw_vsock/virtio_transport.c @@ -208,6 +208,29 @@ virtio_transport_send_pkt_work(struct work_struct *work) queue_work(virtio_vsock_workqueue, &vsock->rx_work); } +/* Caller need to hold RCU for vsock. + * Returns 0 if the packet is successfully put on the vq. + */ +static int virtio_transport_send_skb_fast_path(struct virtio_vsock *vsock, struct sk_buff *skb) +{ + struct virtqueue *vq = vsock->vqs[VSOCK_VQ_TX]; + int ret; + + /* Inside RCU, can't sleep! */ + ret = mutex_trylock(&vsock->tx_lock); + if (unlikely(ret == 0)) + return -EBUSY; + + ret = virtio_transport_send_skb(skb, vq, vsock); + + mutex_unlock(&vsock->tx_lock); + + /* Kick if virtio_transport_send_skb succeeded */ + if (ret == 0) + virtqueue_kick(vq); + return ret; +} + static int virtio_transport_send_pkt(struct sk_buff *skb) { @@ -231,11 +254,18 @@ virtio_transport_send_pkt(struct sk_buff *skb) goto out_rcu; } - if (virtio_vsock_skb_reply(skb)) - atomic_inc(&vsock->queued_replies); + /* If the workqueue (send_pkt_queue) is empty there is no need to enqueue the packet. + * Just put it on the virtqueue using virtio_transport_send_skb_fast_path. + */ - virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb); - queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work); + if (!skb_queue_empty_lockless(&vsock->send_pkt_queue) || + virtio_transport_send_skb_fast_path(vsock, skb)) { + /* Packet must be queued */ + if (virtio_vsock_skb_reply(skb)) + atomic_inc(&vsock->queued_replies); + virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb); + queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work); + } out_rcu: rcu_read_unlock();