(cc'ing Christoph)

On Mon, Aug 22, 2016 at 06:03:48PM +0530, Parav Pandit wrote:

rdmacg: IB/core: rdma controller support

Patch is generated and tested against below Doug's linux-rdma
git tree.

URL: git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma.git
Branch: master

Patchset is also compiled and tested against below Tejun's cgroup tree
using cgroup v2 mode.
URL: git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git
Branch: master

Overview:
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 results into service unavailibility.

RDMA cgroup addresses this issue by allowing resource accounting,
limit enforcement on per cgroup, per rdma device basis.

RDMA uverbs layer will enforce limits on well defined RDMA verb
resources without any HCA vendor device driver involvement.

RDMA uverbs layer will not do limit enforcement of HCA hw vendor
specific resources. Instead rdma cgroup provides set of APIs
through which vendor specific drivers can do resource accounting
by making use of rdma cgroup.

Resource limit enforcement is hierarchical.

When process is migrated with active RDMA resources, rdma cgroup
continues to uncharge original cgroup for allocated resource. New resource
is charged to current process's cgroup, which means if the process is
migrated with active resources, for new resources it will be charged to
new cgroup and old resources will be correctly uncharged from old cgroup.

Changes from v10:
  * (To address comments from Tejun, Christoph)
   1. Removed unused rpool_list_lock from rdma_cgroup structure.
   2. Moved rdma resource definition to rdma cgroup instead of IB stack
   3. Added prefix rdmacg to static instances
   4. Simplified locking with single mutex for all operations
   5. Following approach of atomically allocating object and
      charging resource in hirerchy
   6. Code simplification due to single lock
   7. Using for_each_set_bit API for bit operation
   8. Renamed list heads as Objects instead of _head
   9. Renamed list entries as _node instead of _list.
  10. Made usage_num to 64 bit to avoid overflow and to avoid 
      additional code to track non zero number of usage counts.
  * (To address comments from Doug)
   1. Added copyright and GPLv2 license

Looks good to me.  I just have a nit in the documentation.  Christoph,
what do you think?

Thanks.

-- 
tejun