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Date: Thu, 11 Nov 2010 20:36:37 +0100
From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
To: Andi Kleen <andi@...stfloor.org>
Cc: linux-kernel@...r.kernel.org, fweisbec@...il.com, mingo@...e.hu,
acme@...hat.com, eranian@...gle.com,
Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 1/3] perf-events: Add support for supplementary event
registers
On Thu, 2010-11-11 at 20:25 +0100, Andi Kleen wrote:
> On Thu, Nov 11, 2010 at 08:09:14PM +0100, Peter Zijlstra wrote:
> > > + int percore_used;
> > > + struct intel_percore *per_core;
> >
> > Either per_core != NULL implies percore_used or it should be state
> > inside the struct.
>
> It does not, I'll clarify.
Can we make it so, that is, move that int inside the intel_percore
struct?
> > > +++ b/arch/x86/kernel/cpu/perf_event_intel.c
> > > @@ -1,5 +1,14 @@
> > > #ifdef CONFIG_CPU_SUP_INTEL
> > >
> > > +struct intel_percore {
> > > + raw_spinlock_t lock;
> > > + int ref;
> > > + u64 config;
> > > + unsigned extra_reg;
> > > + u64 extra_config;
> > > +};
> > > +static DEFINE_PER_CPU(struct intel_percore, intel_percore);
> >
> > Please dynamically allocate these when needed, just like the AMD
> > north-bridge structure.
>
> Fully dynamic is difficult because the topology discovery does not
> really handle that nicely.
>
> I can allocate at boot, but it will not save a lot of memory
> (just one entry per core)
>
> To be honest I would prefer not to do that change, are you sure
> you want it?
Hrm,.. but we only need to do this on nhm/wsm init, we already have code
detecting the cpu model. And I'm quite sure you know where to poke to
see if HT is enabled.
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