From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755266AbcHVMgJ (ORCPT ); Mon, 22 Aug 2016 08:36:09 -0400 Received: from mail-pa0-f66.google.com ([209.85.220.66]:34360 "EHLO mail-pa0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754724AbcHVMgC (ORCPT ); Mon, 22 Aug 2016 08:36:02 -0400 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, akpm@linux-foundation.org, linux-security-module@vger.kernel.org, pandit.parav@gmail.com Subject: [PATCHv11 3/3] rdmacg: Added documentation for rdmacg Date: Mon, 22 Aug 2016 18:03:51 +0530 Message-Id: <1471869231-15576-4-git-send-email-pandit.parav@gmail.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1471869231-15576-1-git-send-email-pandit.parav@gmail.com> References: <1471869231-15576-1-git-send-email-pandit.parav@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Added documentation for v1 and v2 version describing high level design and usage examples on using rdma controller. Signed-off-by: Parav Pandit --- Documentation/cgroup-v1/rdma.txt | 117 +++++++++++++++++++++++++++++++++++++++ Documentation/cgroup-v2.txt | 44 +++++++++++++++ 2 files changed, 161 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..7b78678 --- /dev/null +++ b/Documentation/cgroup-v1/rdma.txt @@ -0,0 +1,117 @@ + 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 defines well defined verb resources which can be limited for +processes of a cgroup. + +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 can 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 can be accounted. + +1-3. How is RDMA controller implemented? +---------------------------------------- + +RDMA cgroup allows limit configuration of resources. 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 or requirement 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 is not a 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 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. + +Following resources can be accounted by rdma controller. + uctx Maximum number of User Contexts + pd Maximum number of Protection domains + ah Maximum number of Address handles + mr Maximum number of Memory Regions + mw Maximum number of Memory Windows + cq Maximum number of Completion Queues + srq Maximum number of Shared Receive Queues + qp Maximum number of Queue Pairs + flow Maximum number of Flows + + +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 uctx=max pd=max ah=2 mr=100 mw=max cq=max srq=max qp=10 flow=max +ocrdma1 uctx=1 pd=5 ah=1 mr=10 cq=10 srq=max qp=20 flow=max flow=max + +(c) Query current usage: +cat /sys/fs/cgroup/rdma/2/rdma.current +#Output: +mlx4_0 uctx=1 pd=2 ah=2 mr=95 mw=0 cq=2 srq=0 qp=8 flow=0 +ocrdma1 uctx=1 pd=6 ah=9 mr=20 mw=0 cq=1 srq=0 qp=2 flow=0 + +(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 4cc07ce..cf5a3d3 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 6. Namespace 6-1. Basics 6-2. The Root and Views @@ -1119,6 +1121,48 @@ writeback as follows. vm.dirty[_background]_ratio. +5-4. RDMA + +The "rdma" controller regulates the distribution and accounting of +of RDMA resources. + +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. + + Following keys are defined. + + uctx Maximum number of User Contexts + pd Maximum number of Protection domains + ah Maximum number of Address handles + mr Maximum number of Memory Regions + mw Maximum number of Memory Windows + cq Maximum number of Completion Queues + srq Maximum number of Shared Receive Queues + qp Maximum number of Queue Pairs + flow Maximum number of Flows + + An example for mlx4 and ocrdma device follows. + + mlx4_0 uctx=max pd=4 ah=2 mr=10 mw=max cq=1 srq=1 qp=10 flow=10 + ocrdma1 uctx=2 pd=2 ah=2 mr=20 mw=max cq=1 srq=1 qp=10 flow=10 + + 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_1 uctx=1 ah=0 pd=1 cq=4 qp=4 mr=100 srq=0 flow=10 + ocrdma1 uctx=2 pd=2 ah=2 mr=20 mw=max cq=1 srq=1 qp=10 flow=10 + + 6. Namespace 6-1. Basics -- 1.8.3.1