linux-kernel - Re: [PATCH 02/10] x86, perf: Support sysfs files depending on SMT status

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Message-ID: <20160509143420.GA3408@twins.programming.kicks-ass.net>
Date:	Mon, 9 May 2016 16:34:20 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Andi Kleen <ak@...ux.intel.com>
Cc:	Andi Kleen <andi@...stfloor.org>, acme@...nel.org,
	jolsa@...nel.org, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org
Subject: Re: [PATCH 02/10] x86, perf: Support sysfs files depending on SMT
 status

On Mon, May 09, 2016 at 07:27:41AM -0700, Andi Kleen wrote:
> On Mon, May 09, 2016 at 11:42:19AM +0200, Peter Zijlstra wrote:
> > On Thu, May 05, 2016 at 04:03:59PM -0700, Andi Kleen wrote:
> > > From: Andi Kleen <ak@...ux.intel.com>
> > > 
> > > Add a way to show different sysfs events attributes depending on
> > > HyperThreading is on or off. This is difficult to determine
> > > early at boot, so we just do it dynamically when the sysfs
> > > attribute is read.
> > > 
> > > v2:
> > > Compute HT status only once in CPU online/offline hooks.
> > > v3: Use topology_max_smt_threads()
> > > Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> > > ---
> > >  arch/x86/events/core.c       | 24 ++++++++++++++++++++++++
> > >  arch/x86/events/perf_event.h | 14 ++++++++++++++
> > >  include/linux/perf_event.h   |  7 +++++++
> > >  3 files changed, 45 insertions(+)
> > > 
> > 
> > Should this not now live in /sys/devices/system/cpu/ ? Thomas?
> 
> This would be incompatible to all previous perf tools.
> 
> Also not clear why you would want to move such events, just
> because they depend on SMT.

Durr, my bad; I read the patch wrong. I'll go have another look.

Thanks