linux-kernel - Re: [PATCH v2 00/11] perf: Intel Cache QoS Monitoring support

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Message-ID: <20141002065124.GF14343@console-pimps.org>
Date:	Thu, 2 Oct 2014 07:51:24 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
	Matt Fleming <matt.fleming@...el.com>
Subject: Re: [PATCH v2 00/11] perf: Intel Cache QoS Monitoring support

On Wed, 01 Oct, at 02:42:05PM, Andi Kleen wrote:
> Matt Fleming <matt@...sole-pimps.org> writes:
> >
> > Changes in v2:
> >
> >  - Added Jiri Olsa's Acked-by to PATCH 02/11.
> >
> >  - Use x86_match_cpu() in intel_cqm_init() and make sure we grab the
> >    hotplug lock to prevent races as pointed out by Andi Kleen in
> >    PATCH 08/11.
> >
> >  - Delete a stale comment in commit message of PATCH 10/11.
> 
> No support for a modular driver?

I didn't include support for that because none of the other x86 pmu
drivers are buildable as modules. Is there a reason for that?

It's not clear to me that it would be a worthwhile change to make this
buildable as a module, since that would require a Kconfig entry and the
user would be required to make a decision regarding whether or not they
want to build CQM support.

It's much simpler to just build it in and enable it based on
CONFIG_PERF_EVENTS + CONFIG_INTEL_CPU. In fact, that's one of the things
I've always liked about the pmu drivers, if I move to a new machine and
turn on PERF_EVENTS the correct drivers will be run.

-- 
Matt Fleming, Intel Open Source Technology Center
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