linux-kernel - Re: [perf] enable raw OFFCORE_EVENTS for non-perf userspace

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Message-ID: <alpine.DEB.2.00.1108042221450.3022@cl320.eecs.utk.edu>
Date:	Thu, 4 Aug 2011 22:24:58 -0400
From:	Vince Weaver <vweaver1@...s.utk.edu>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC:	<linux-kernel@...r.kernel.org>, Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Stephane Eranian <eranian@...il.com>
Subject: Re: [perf] enable raw OFFCORE_EVENTS for non-perf userspace

On Thu, 4 Aug 2011, Peter Zijlstra wrote:

> On Wed, 2011-08-03 at 12:05 -0400, Vince Weaver wrote:
> 
> > diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
> > index 4ee3abf..28f9ca9 100644
> > --- a/arch/x86/kernel/cpu/perf_event.c
> > +++ b/arch/x86/kernel/cpu/perf_event.c
> > @@ -604,12 +604,8 @@ static int x86_setup_perfctr(struct perf_event *event)
> >  			return -EOPNOTSUPP;
> >  	}
> >  
> > -	/*
> > -	 * Do not allow config1 (extended registers) to propagate,
> > -	 * there's no sane user-space generalization yet:
> > -	 */
> >  	if (attr->type == PERF_TYPE_RAW)
> > -		return 0;
> > +		return x86_pmu_extra_regs(event->attr.config, event);
> >  
> >  	if (attr->type == PERF_TYPE_HW_CACHE)
> >  		return set_ext_hw_attr(hwc, event);
> 
> 
> I'm inclined to merge this, aside from snb, the offcore stuff is
> actually quite usable now. Ingo can we somehow persuade you?

This would make me happy.  The patch is more or less a revert of the patch 
that disabled support in the first place, but if you need my signed-off-by 
(I forgot it before) here it is

Signed-off-by: Vince Weaver <vweaver1@...s.utk.edu>

> Anybody who knows how to program the snb offcore please tell. I mean we
> have all the code to poke at the right registers, and the SDM lists all
> the various bits that go where and a few constraints on how to combine
> said bits, but I've really no idea what any of it means.

I've added Stephane as I think he did some work on SandyBridge offcore.

Vince

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