linux-kernel - Re: [PATCH 04/10] perf, x86: Making hardware events translations available in sysfs

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Message-ID: <1341397738.2507.92.camel@laptop>
Date:	Wed, 04 Jul 2012 12:28:58 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	acme@...hat.com, mingo@...e.hu, paulus@...ba.org,
	cjashfor@...ux.vnet.ibm.com, fweisbec@...il.com,
	eranian@...gle.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/10] perf, x86: Making hardware events translations
 available in sysfs

On Wed, 2012-07-04 at 12:24 +0200, Peter Zijlstra wrote:
> On Wed, 2012-07-04 at 00:00 +0200, Jiri Olsa wrote:
> > +static struct attribute *events_attr[] = {
> > +       &event_attr_cycles.attr,
> > +       &event_attr_instructions.attr,
> > +       &event_attr_cache_references.attr,
> > +       &event_attr_cache_misses.attr,
> > +       &event_attr_branch_instructions.attr,
> > +       &event_attr_branch_misses.attr,
> > +       &event_attr_bus_cycles.attr,
> > +       &event_attr_stalled_cycles_frontend.attr,
> > +       &event_attr_stalled_cycles_backend.attr,
> > +       &event_attr_ref_cycles.attr,
> > +       NULL,
> > +}; 
> 
> Hmm, should we do:
> 
>   if (!config)
>     return -EINVAL;
> 
> or somesuch to clearly indicate an event isn't supported?
> 
> Its currently a bit of a mixed bag between 0 and -1.. we might want to
> clean that up too.

Alternatively, we'd do something like:

  for (i = 0; events_attr[i]; i++) {
    if (x86_pmu.event_map(i))
      continue;

    for (j = i; events_attr[j]; j++)
      events_attr[j] = events_attr[j+1];
  }

On init to filter out all unset events so they don't even show up in
sysfs.
      

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