linux-kernel - Re: [PATCH v2 4/4] perf/x86/uncore: modularize Intel uncore driver

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Message-ID: <20140424081408.GA7709@gmail.com>
Date:	Thu, 24 Apr 2014 10:14:08 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	"Yan, Zheng" <zheng.z.yan@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH v2 4/4] perf/x86/uncore: modularize Intel uncore driver


* Stephane Eranian <eranian@...gle.com> wrote:

> >> Most of the codes without comments are hardware specific codes. 
> >> The corresponding contents in Intel uncore documents are big 
> >> tables/lists, nothing tricky/interesting. I really don't know how 
> >> to comment these code.
> >
> > Have a look at other PMU drivers, such as
> > arch/x86/kernel/cpu/perf_event_intel_rapl.c, which begin with a
> > general explanation attached below.
>
> I think a more useful modularization would be to split that huge 
> file (perf_event_intel_uncore.c) into smaller files like we do for 
> the core PMU. There is just too much stuff in this file for my own 
> taste. Hard to navigate and I spend quite some time looking at it 
> and modifying it!
> 
> You could follow the model of the core PMU support files.
> You'd have a "core" file with the common routines, and then
> a file perf processor:
>     - perf_event_intel_uncore.c
>     - perf_event_intel_snbep_uncore.c
>     - perf_event_intel_nhmex_uncore.c
>     - perf_event_intel_ivt_uncore.c
>     - ...
> 
> Each processor specific module, would be a kernel module. The core 
> could be one too. Note that this would not alleviate the need for 
> some basic descriptions at the beginning of each file outlining the 
> PMU boxes exported to a minimum.

This structure you outline sounds like a good first step, I like it.

To simplify this restructuring, initially we could even keep the core 
uncore bits in the core (ha!), to not have module-on-module 
dependencies.

Thanks,

	Ingo
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