Re: [PATCH 00/12] Cqm2: Intel Cache quality monitoring fixes

[Shivappa Vikas]

Hello Peterz,

On Wed, 18 Jan 2017, Peter Zijlstra wrote:

> On Wed, Jan 18, 2017 at 09:53:02AM +0100, Thomas Gleixner wrote:
> > The whole approach you and David have taken is to whack some desired cgroup
> > functionality and whatever into CQM without rethinking the overall
> > design. And that's fundamentaly broken because it does not take cache (and
> > memory bandwidth) allocation into account.
> >
> > I seriously doubt, that the existing CQM/MBM code can be refactored in any
> > useful way. As Peter Zijlstra said before: Remove the existing cruft
> > completely and start with completely new design from scratch.
> >
> > And this new design should start from the allocation angle and then add the
> > whole other muck on top so far its possible. Allocation related monitoring
> > must be the primary focus, everything else is just tinkering.
>
> Agreed, the little I have seen of these patches is quite horrible. And
> there seems to be a definite lack of design; or at the very least an
> utter lack of communication of it.

the 1/12 Documentation patch describes the interface. Basically we are just 
trying to support the task and cgroup monitoring.

By the design document, do you want a document describing how we enable the 
cgroup for cqm since its a special case?
(which would include all the arch_info in the perf_cgroup we add to keep track 
of hierarchy in the driver , etc ..)

Thanks,
Vikas

> The approach, in so far that I could make sense of it, seems to utterly
> rape perf-cgroup. I think Thomas makes a sensible point in trying to
> match it to the CAT stuffs.