From patchwork Mon Jul 20 12:22:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Haakon Bugge X-Patchwork-Id: 11673677 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5975717C5 for ; Mon, 20 Jul 2020 12:23:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3DF9E22B4E for ; Mon, 20 Jul 2020 12:23:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="CxSphOvM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728460AbgGTMXN (ORCPT ); Mon, 20 Jul 2020 08:23:13 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:52928 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728791AbgGTMXN (ORCPT ); Mon, 20 Jul 2020 08:23:13 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 06KCIWVO138268; Mon, 20 Jul 2020 12:23:07 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type : content-transfer-encoding; s=corp-2020-01-29; bh=nJUPegOSWINxuKUWZYKo4l3zNYLMoxhXPpc+tGkChwc=; b=CxSphOvM3zxxDXD7pFkjGn9dzfTYzbIxsSFgNrlHmHsbP3hpL6zdoCVg8iusxCdpTvvk ojw/HtQHmK/MWwDxLDDYuZFNFh7Tr5qw4lr7Rq/Os8nJjvgvzzxwo5nZmTsADFZUYOT7 1D56R75Wp31e/lSxbsmazQnX5SvP2/xePUmlxtNK8Tc+l+DwaEdTkO3Te3bRMyRCPI7p t4AVFTLUanpdsVeq5CYoi+odTNJ5FZgTXGBWX7Cm/7+wQi/cJ/GrfVGgt7iyZmL9t3U8 1f8YQ125xlAC4hdaz7iK+wMWPAZHDqlO0jaDm3NmDAMZ7bE3i5avhxgzIXMghGf9vd5P xQ== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by aserp2120.oracle.com with ESMTP id 32bs1m6jpw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 20 Jul 2020 12:23:06 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 06KCDuFF027181; Mon, 20 Jul 2020 12:23:06 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3030.oracle.com with ESMTP id 32d8kyqmp0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 20 Jul 2020 12:23:06 +0000 Received: from abhmp0013.oracle.com (abhmp0013.oracle.com [141.146.116.19]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 06KCN5oN007150; Mon, 20 Jul 2020 12:23:05 GMT Received: from lab02.no.oracle.com (/10.172.144.56) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 20 Jul 2020 05:23:05 -0700 From: =?utf-8?q?H=C3=A5kon_Bugge?= To: Doug Ledford , Jason Gunthorpe Cc: linux-rdma@vger.kernel.org, Yishai Hadas , Jack Morgenstein Subject: [PATCH for-rc 4/5] IB/mlx4: Fix starvation in paravirt mux/demux Date: Mon, 20 Jul 2020 14:22:48 +0200 Message-Id: <20200720122249.487086-5-haakon.bugge@oracle.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200720122249.487086-1-haakon.bugge@oracle.com> References: <20200720122249.487086-1-haakon.bugge@oracle.com> MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9687 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 phishscore=0 mlxscore=0 malwarescore=0 mlxlogscore=999 bulkscore=0 adultscore=0 suspectscore=2 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007200085 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9687 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 bulkscore=0 adultscore=0 lowpriorityscore=0 mlxlogscore=999 malwarescore=0 clxscore=1015 spamscore=0 mlxscore=0 impostorscore=0 phishscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007200085 Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org The mlx4 driver will proxy MAD packets through the PF driver. A VM or an instantiated VF will send its MAD packets to the PF driver using loop-back. The PF driver will be informed by an interrupt, but defer the handling and polling of CQEs to a worker thread running on an ordered work-queue. Consider the following scenario: the VMs will in short proximity in time, for example due to a network event, send many MAD packets to the PF driver. Lets say there are K VMs, each sending N packets. The interrupt from the first VM will start the worker thread, which will poll N CQEs. A common case here is where the PF driver will multiplex the packets received from the VMs out on the wire QP. But before the wire QP has returned a send CQE and associated interrupt, the other K - 1 VMs has sent their N packets. The PF driver will have to multiplex K * N packets out on the wire QP. But the send-queue on the wire QP has a finite capacity. So, in this scenario, if K * N is larger that the send-queue capacity of the wire QP, we will get MAD packets dropped on the floor with this dynamic debug message: mlx4_ib_multiplex_mad: failed sending GSI to wire on behalf of slave 2 (-11) and this despite the fact that the wire send-queue could have capacity, but the PF driver isn't aware, because the wire send CQEs have not yet been polled. We can also have a similar scenario inbound, with a wire recv-queue larger than the tunnel QP's recv queue. If many remote peers sends MAD packets to the very same VM, the tunnel send-queue destined to the VM could overflow. This starvation is fixed by introducing separate work queues for the wire QPs vs. the tunnel QPs With this fix, using a dual ported HCA, 8 VFs instantiated, we could run cmtime on each of the 18 interfaces towards a similar configured peer, each cmtime instance with 800 QPs (all in all 14400 QPs) without a single CM packet getting lost. Signed-off-by: Håkon Bugge --- drivers/infiniband/hw/mlx4/mad.c | 34 +++++++++++++++++++++++++--- drivers/infiniband/hw/mlx4/mlx4_ib.h | 2 ++ 2 files changed, 33 insertions(+), 3 deletions(-) diff --git a/drivers/infiniband/hw/mlx4/mad.c b/drivers/infiniband/hw/mlx4/mad.c index 336b894de7cf..28bf8ddb019e 100644 --- a/drivers/infiniband/hw/mlx4/mad.c +++ b/drivers/infiniband/hw/mlx4/mad.c @@ -1278,6 +1278,18 @@ static void mlx4_ib_tunnel_comp_handler(struct ib_cq *cq, void *arg) spin_unlock_irqrestore(&dev->sriov.going_down_lock, flags); } +static void mlx4_ib_wire_comp_handler(struct ib_cq *cq, void *arg) +{ + unsigned long flags; + struct mlx4_ib_demux_pv_ctx *ctx = cq->cq_context; + struct mlx4_ib_dev *dev = to_mdev(ctx->ib_dev); + + spin_lock_irqsave(&dev->sriov.going_down_lock, flags); + if (!dev->sriov.is_going_down && ctx->state == DEMUX_PV_STATE_ACTIVE) + queue_work(ctx->wi_wq, &ctx->work); + spin_unlock_irqrestore(&dev->sriov.going_down_lock, flags); +} + static int mlx4_ib_post_pv_qp_buf(struct mlx4_ib_demux_pv_ctx *ctx, struct mlx4_ib_demux_pv_qp *tun_qp, int index) @@ -1986,7 +1998,8 @@ static int create_pv_resources(struct ib_device *ibdev, int slave, int port, cq_size *= 2; cq_attr.cqe = cq_size; - ctx->cq = ib_create_cq(ctx->ib_dev, mlx4_ib_tunnel_comp_handler, + ctx->cq = ib_create_cq(ctx->ib_dev, + create_tun ? mlx4_ib_tunnel_comp_handler : mlx4_ib_wire_comp_handler, NULL, ctx, &cq_attr); if (IS_ERR(ctx->cq)) { ret = PTR_ERR(ctx->cq); @@ -2023,6 +2036,7 @@ static int create_pv_resources(struct ib_device *ibdev, int slave, int port, INIT_WORK(&ctx->work, mlx4_ib_sqp_comp_worker); ctx->wq = to_mdev(ibdev)->sriov.demux[port - 1].wq; + ctx->wi_wq = to_mdev(ibdev)->sriov.demux[port - 1].wi_wq; ret = ib_req_notify_cq(ctx->cq, IB_CQ_NEXT_COMP); if (ret) { @@ -2166,7 +2180,7 @@ static int mlx4_ib_alloc_demux_ctx(struct mlx4_ib_dev *dev, goto err_mcg; } - snprintf(name, sizeof name, "mlx4_ibt%d", port); + snprintf(name, sizeof(name), "mlx4_ibt%d", port); ctx->wq = alloc_ordered_workqueue(name, WQ_MEM_RECLAIM); if (!ctx->wq) { pr_err("Failed to create tunnelling WQ for port %d\n", port); @@ -2174,7 +2188,15 @@ static int mlx4_ib_alloc_demux_ctx(struct mlx4_ib_dev *dev, goto err_wq; } - snprintf(name, sizeof name, "mlx4_ibud%d", port); + snprintf(name, sizeof(name), "mlx4_ibwi%d", port); + ctx->wi_wq = alloc_ordered_workqueue(name, WQ_MEM_RECLAIM); + if (!ctx->wi_wq) { + pr_err("Failed to create wire WQ for port %d\n", port); + ret = -ENOMEM; + goto err_wiwq; + } + + snprintf(name, sizeof(name), "mlx4_ibud%d", port); ctx->ud_wq = alloc_ordered_workqueue(name, WQ_MEM_RECLAIM); if (!ctx->ud_wq) { pr_err("Failed to create up/down WQ for port %d\n", port); @@ -2185,6 +2207,10 @@ static int mlx4_ib_alloc_demux_ctx(struct mlx4_ib_dev *dev, return 0; err_udwq: + destroy_workqueue(ctx->wi_wq); + ctx->wi_wq = NULL; + +err_wiwq: destroy_workqueue(ctx->wq); ctx->wq = NULL; @@ -2232,12 +2258,14 @@ static void mlx4_ib_free_demux_ctx(struct mlx4_ib_demux_ctx *ctx) ctx->tun[i]->state = DEMUX_PV_STATE_DOWNING; } flush_workqueue(ctx->wq); + flush_workqueue(ctx->wi_wq); for (i = 0; i < dev->dev->caps.sqp_demux; i++) { destroy_pv_resources(dev, i, ctx->port, ctx->tun[i], 0); free_pv_object(dev, i, ctx->port); } kfree(ctx->tun); destroy_workqueue(ctx->ud_wq); + destroy_workqueue(ctx->wi_wq); destroy_workqueue(ctx->wq); } } diff --git a/drivers/infiniband/hw/mlx4/mlx4_ib.h b/drivers/infiniband/hw/mlx4/mlx4_ib.h index 8999fecb045b..20cfa69d0aed 100644 --- a/drivers/infiniband/hw/mlx4/mlx4_ib.h +++ b/drivers/infiniband/hw/mlx4/mlx4_ib.h @@ -455,6 +455,7 @@ struct mlx4_ib_demux_pv_ctx { struct ib_pd *pd; struct work_struct work; struct workqueue_struct *wq; + struct workqueue_struct *wi_wq; struct mlx4_ib_demux_pv_qp qp[2]; }; @@ -462,6 +463,7 @@ struct mlx4_ib_demux_ctx { struct ib_device *ib_dev; int port; struct workqueue_struct *wq; + struct workqueue_struct *wi_wq; struct workqueue_struct *ud_wq; spinlock_t ud_lock; atomic64_t subnet_prefix;