Date: Sat, 4 Jan 2014 11:10:50 -0500
From: Tejun Heo <tj@kernel.org>
To: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Li Zefan <lizefan@huawei.com>,
        containers@lists.linux-foundation.org, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/4] x86: Add Cache QoS Monitoring (CQM) support
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Hello,

On Fri, Jan 03, 2014 at 12:34:41PM -0800, Peter P Waskiewicz Jr wrote:
> The CPU features themselves are relatively straight-forward, but
> the presentation of the data is less straight-forward.  Since this
> tracks cache usage and occupancy per process (by swapping Resource
> Monitor IDs, or RMIDs, when processes are rescheduled), perf would
> not be a good fit for this data, which does not report on a
> per-process level.  Therefore, a new cgroup subsystem, cacheqos, has
> been added.  This operates very similarly to the cpu and cpuacct
> cgroup subsystems, where tasks can be grouped into sub-leaves of the
> root-level cgroup.

I don't really understand why this is implemented as part of cgroup.
There doesn't seem to be anything which requires cgroup.  Wouldn't
just doing it per-process make more sense?  Even grouping would be
better done along the traditional process hierarchy, no?  And
per-cgroup accounting can be trivially achieved from userland by just
accumulating the stats according to the process's cgroup membership.
What am I missing here?

Thanks.

-- 
tejun
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