linux-kernel - Re: [PATCH 08/11] perf/x86/intel: Add Intel Cache QoS Monitoring support

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Message-ID: <20140929185140.GA14343@console-pimps.org>
Date:	Mon, 29 Sep 2014 19:51:40 +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>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 08/11] perf/x86/intel: Add Intel Cache QoS Monitoring
 support

On Wed, 24 Sep, at 10:39:37PM, Andi Kleen wrote:
> On Wed, Sep 24, 2014 at 09:27:39PM +0100, Matt Fleming wrote:
> > > > +static int __init intel_cqm_init(void)
> > > > +{
> > > > +	int i, cpu, ret;
> > > > +
> > > > +	if (!cpu_has(&boot_cpu_data, X86_FEATURE_CQM_OCCUP_LLC))
> > > > +		return -ENODEV;
> > > 
> > > This should use cpufeature.h
> >  
> > What? Please be more explicit.
> 
> Using x86_match_cpu and friends, then it would work for module
> auto loading too.
 
OK, I'll take a look at that, thanks.

> > > But in fact what good is the test then if you only
> > > every likely check cpu #0?
> > 
> > We don't, we check every online cpu, not just cpu 0.
> 
> There are no other cpus online at this point?

There are definitely other cpus online at this point, smp_init() gets
called before do_initcalls().

-- 
Matt Fleming, Intel Open Source Technology Center
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