From patchwork Tue Mar 1 19:05:37 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Parav Pandit X-Patchwork-Id: 8469291 Return-Path: X-Original-To: patchwork-linux-rdma@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id EE869C0553 for ; Tue, 1 Mar 2016 19:07:56 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id CA83820304 for ; Tue, 1 Mar 2016 19:07:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82672202B8 for ; Tue, 1 Mar 2016 19:07:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752237AbcCATHX (ORCPT ); Tue, 1 Mar 2016 14:07:23 -0500 Received: from mail-pa0-f51.google.com ([209.85.220.51]:35818 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753582AbcCATHH (ORCPT ); Tue, 1 Mar 2016 14:07:07 -0500 Received: by mail-pa0-f51.google.com with SMTP id bj10so48140185pad.2; Tue, 01 Mar 2016 11:07:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=+NgjnkLFzve7cyU3lUrhLsPTbERTBPYFUn9taKJ0UVw=; b=jTwnL6EsqVFVhy1TlO9ptbISyb2tCUOYmvyHgMLnmwJSNIl94B7/Pvy8sgN7Ox9X4M RyTh5dqxaiOJZpRT/qjT34gY99qpMHk0ZhLmGYNW1da+lZnTcgL4RmhNr53OWqo4/M9S Az8PjrP8GWT0QtwWKue+4PbppB/BcDZ0dQ+NH5aWYje+SRoanK3CRP494+ohR75hvAmY LagbFmcUTWZpIEjgRti5lojH2oBk3yffQzcq+OY2T4NtOQfpoMJn2NJ17/GM1kcNIlbC DP3keVuw6RKrcuaKnAtisaxMMCxZERqf92VcND483LtOI7uSda4CiOdYQiuw+QAmmbWm 2BQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=+NgjnkLFzve7cyU3lUrhLsPTbERTBPYFUn9taKJ0UVw=; b=f7H2FX2cDHHYOFJ8soolvRoFBIVTkp3oN+J20UYAHRWwRTmj8/4M9RRG7uHib1nzUW UHfPjv5hK3WG1B5UKMp8nqB5jUU4WXSudELB03i9LPJR5anIS3AX7urVEiZOHbfZwVAQ 0zV/7EC6EpIwgLo+ITt9XFtZ6ar3YvNSZ1Rjldl6WnjLKsDtXaU5tpygXHdQnhroY5n1 leZdT+CfSbLsDYiXmTdGdt/P4X0KUk19TGuwGKGm/5MHmdcBUzCC2whlxAdvZyRPcWa+ ubDEiUtQX9Ng4uoO2s7cyWexonemPWm8EhtJU+6eB3EHZ5QRgKYbM6+4lRcNh9qG3TWB yS7A== X-Gm-Message-State: AD7BkJL6i+Ut8Ofon0FvIQstOBE+0TRhgsf7k5lBqLbWc+hb4yPXIyKQKXSnNxrllzs/Wg== X-Received: by 10.66.157.161 with SMTP id wn1mr32703806pab.146.1456859226445; Tue, 01 Mar 2016 11:07:06 -0800 (PST) Received: from server1.localdomain ([106.216.175.216]) by smtp.gmail.com with ESMTPSA id tn5sm47374928pac.32.2016.03.01.11.06.59 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 01 Mar 2016 11:07:05 -0800 (PST) From: Parav Pandit To: cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, tj@kernel.org, lizefan@huawei.com, hannes@cmpxchg.org, dledford@redhat.com, liranl@mellanox.com, sean.hefty@intel.com, jgunthorpe@obsidianresearch.com, haggaie@mellanox.com Cc: corbet@lwn.net, james.l.morris@oracle.com, serge@hallyn.com, ogerlitz@mellanox.com, matanb@mellanox.com, raindel@mellanox.com, akpm@linux-foundation.org, linux-security-module@vger.kernel.org, pandit.parav@gmail.com Subject: [PATCHv9 3/3] rdmacg: Added documentation for rdmacg Date: Wed, 2 Mar 2016 00:35:37 +0530 Message-Id: <1456859137-13646-4-git-send-email-pandit.parav@gmail.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1456859137-13646-1-git-send-email-pandit.parav@gmail.com> References: <1456859137-13646-1-git-send-email-pandit.parav@gmail.com> MIME-Version: 1.0 Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Added documentation for v1 and v2 version describing high level design and usage examples on using rdma controller. Signed-off-by: Parav Pandit Reviewed-by: Haggai Eran --- Documentation/cgroup-v1/rdma.txt | 111 +++++++++++++++++++++++++++++++++++++++ Documentation/cgroup-v2.txt | 33 ++++++++++++ 2 files changed, 144 insertions(+) create mode 100644 Documentation/cgroup-v1/rdma.txt diff --git a/Documentation/cgroup-v1/rdma.txt b/Documentation/cgroup-v1/rdma.txt new file mode 100644 index 0000000..1973502 --- /dev/null +++ b/Documentation/cgroup-v1/rdma.txt @@ -0,0 +1,111 @@ + RDMA Controller + ---------------- + +Contents +-------- + +1. Overview + 1-1. What is RDMA controller? + 1-2. Why RDMA controller needed? + 1-3. How is RDMA controller implemented? +2. Usage Examples + +1. Overview + +1-1. What is RDMA controller? +----------------------------- + +RDMA controller allows user to limit RDMA/IB specific resources +that a given set of processes can use. These processes are grouped using +RDMA controller. + +RDMA controller allows operating on resources defined by the IB stack +which are mainly IB verb resources and in future hardware specific +well defined resources. + +1-2. Why RDMA controller needed? +-------------------------------- + +Currently user space applications can easily take away all the rdma device +specific resources such as AH, CQ, QP, MR etc. Due to which other applications +in other cgroup or kernel space ULPs may not even get chance to allocate any +rdma resources. This leads to service unavailability. + +Therefore RDMA controller is needed through which resource consumption +of processes can be limited. Through this controller various different rdma +resources described by IB stack can be accounted. + +1-3. How is RDMA controller implemented? +---------------------------------------- + +RDMA cgroup allows limit configuration of resources. These resources are not +defined by the rdma controller. Instead they are defined by the IB stack. +This provides great flexibility to allow IB stack to define new resources, +without any changes to rdma cgroup. +Rdma cgroup maintains resource accounting per cgroup, per device using +resource pool structure. Each such resource pool is limited up to +64 resources in given resource pool by rdma cgroup, which can be extended +later if required. + +This resource pool object is linked to the cgroup css. Typically there +are 0 to 4 resource pool instances per cgroup, per device in most use cases. +But nothing limits to have it more. At present hundreds of RDMA devices per +single cgroup may not be handled optimally, however there is no +known use case for such configuration either. + +Since RDMA resources can be allocated from any process and can be freed by any +of the child processes which shares the address space, rdma resources are +always owned by the creator cgroup css. This allows process migration from one +to other cgroup without major complexity of transferring resource ownership; +because such ownership is not really present due to shared nature of +rdma resources. Linking resources around css also ensures that cgroups can be +deleted after processes migrated. This allow progress migration as well with +active resources, even though that’s not the primary use case. + +Whenever RDMA resource charing occurs, owner rdma cgroup is returned to +the caller. Same rdma cgroup should be passed while uncharging the resource. +This also allows process migrated with active RDMA resource to charge +to new owner cgroup for new resource. It also allows to uncharge resource of +a process from previously charged cgroup which is migrated to new cgroup, +even though that is not a primary use case. + +Resource pool object is created in following situations. +(a) User sets the limit and no previous resource pool exist for the device +of interest for the cgroup. +(b) No resource limits were configured, but IB/RDMA stack tries to +charge the resource. So that it correctly uncharge them when applications are +running without limits and later on when limits are enforced during uncharging, +otherwise usage count will drop to negative. + +Resource pool is destroyed if it all the resource limits are set to max +and it is the last resource getting deallocated. + +User should set all the limit to max value if it intents to remove/unconfigure +the resource pool for a particular device. + +IB stack honors limits enforced by the rdma controller. When application +query about maximum resource limits of IB device, it returns minimum of +what is configured by user for a given cgroup and what is supported by +IB device. + +2. Usage Examples +----------------- + +(a) Configure resource limit: +echo mlx4_0 mr=100 qp=10 ah=2 > /sys/fs/cgroup/rdma/1/rdma.max +echo ocrdma1 mr=120 qp=20 cq=10 > /sys/fs/cgroup/rdma/2/rdma.max + +(b) Query resource limit: +cat /sys/fs/cgroup/rdma/2/rdma.max +#Output: +mlx4_0 mr=100 qp=10 ah=2 pd=max +ocrdma1 mr=120 qp=20 cq=10 pd=max ah=max + +(c) Query current usage: +cat /sys/fs/cgroup/rdma/2/rdma.current +#Output: +mlx4_0 mr=95 qp=8 ah=2 +ocrdma1 mr=0 qp=20 cq=10 + +(d) Delete resource limit: +echo mlx4_0 mr=max qp=max ah=max > /sys/fs/cgroup/rdma/1/rdma.max diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt index ff49cf9..0ec4605 100644 --- a/Documentation/cgroup-v2.txt +++ b/Documentation/cgroup-v2.txt @@ -47,6 +47,8 @@ CONTENTS 5-3. IO 5-3-1. IO Interface Files 5-3-2. Writeback + 5-4. RDMA + 5-4-1. RDMA Interface Files P. Information on Kernel Programming P-1. Filesystem Support for Writeback D. Deprecated v1 Core Features @@ -1088,6 +1090,37 @@ writeback as follows. total available memory and applied the same way as vm.dirty[_background]_ratio. +5-4. RDMA + +The "rdma" controller regulates the distribution of RDMA resources. +This controller implements resource accounting of resources defined +by IB stack. + +5-4-1. RDMA Interface Files + + rdma.max + A readwrite file that exists for all the cgroups except root that + describes current configured resource limit for a RDMA/IB device. + + Lines are keyed by device name and are not ordered. + Each line contains space separated resource name and its configured + limit that can be distributed. + + An example for mlx4 and ocrdma device follows. + + mlx4_0 ah=2 mr=1000 qp=104 + ocrdma1 cq=10 mr=900 qp=89 + mlx4_1 uctx=max ah=max pd=max cq=max qp=max + + rdma.current + A read-only file that describes current resource usage. + It exists for all the cgroup except root. + + An example for mlx4 and ocrdma device follows. + + mlx4_0 mr=1000 qp=102 ah=2 flow=10 srq=0 + ocrdma1 mr=900 qp=79 cq=10 flow=0 srq=0 + mlx4_1 uctx=max ah=max pd=max cq=max qp=max P. Information on Kernel Programming