linux-kernel - Re: [PATCHv1 3/6] rdmacg: implements rdma cgroup

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Message-ID: <20160107202818.GF1898@mtj.duckdns.org>
Date:	Thu, 7 Jan 2016 15:28:18 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Parav Pandit <pandit.parav@...il.com>
Cc:	cgroups@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
	lizefan@...wei.com, Johannes Weiner <hannes@...xchg.org>,
	Doug Ledford <dledford@...hat.com>,
	Liran Liss <liranl@...lanox.com>,
	"Hefty, Sean" <sean.hefty@...el.com>,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
	Haggai Eran <haggaie@...lanox.com>,
	Jonathan Corbet <corbet@....net>, james.l.morris@...cle.com,
	serge@...lyn.com, Or Gerlitz <ogerlitz@...lanox.com>,
	Matan Barak <matanb@...lanox.com>, raindel@...lanox.com,
	akpm@...ux-foundation.org, linux-security-module@...r.kernel.org
Subject: Re: [PATCHv1 3/6] rdmacg: implements rdma cgroup

Hello, Parav.

On Fri, Jan 08, 2016 at 01:55:09AM +0530, Parav Pandit wrote:
...
> Above functionality is achieved, by maintaining the map this tgid and
> associated original cgroup at try_charge(), uncharge() time.

Hmmm, what happens after the following?

1. A process allocates some rdma resources and get registered on the
   hash table.

2. The process gets migrated to a different cgroup.

3. The process allocates more rdma resources.

Which cgroup would the resources from #3 be attributed to?

> In alternate method,
> Its simple to store the pointer of rdma_cgroup structure in the IB
> resource structure and hold on reference count to rdma_cgroup.
> so that when its freed, uncharge_resource can accept rdma_cgroup
> structure pointer.

That'd be a lot more in line with how other controllers behave.

Thanks.

-- 
tejun