linux-kernel - Re: [PATCH] perf/x86/intel: Export mem events only if there's PEBs support

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Message-ID: <20180828081232.GI24124@hirez.programming.kicks-ass.net>
Date:   Tue, 28 Aug 2018 10:12:32 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Jiri Olsa <jolsa@...nel.org>, lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH] perf/x86/intel: Export mem events only if there's PEBs
 support

On Mon, Aug 27, 2018 at 11:06:24AM +0200, Jiri Olsa wrote:
> +static __init struct attribute **get_hsw_events_attrs(bool *alloc)
>  {
> +	if (boot_cpu_has(X86_FEATURE_RTM)) {
> +		*alloc = true;
> +		return merge_attr(hsw_events_attrs, hsw_tsx_events_attrs);
> +	}
> +	return hsw_events_attrs;
>  }



> @@ -4357,6 +4374,15 @@ __init int intel_pmu_init(void)
>  		WARN_ON(!x86_pmu.format_attrs);
>  	}
>  
> +	if (x86_pmu.pebs && mem_attr) {
> +		struct attribute **attr = x86_pmu.cpu_events;
> +
> +		x86_pmu.cpu_events = merge_attr(x86_pmu.cpu_events, mem_attr);
> +
> +		if (alloc_events)
> +			kfree(attr);
> +	}
> +
>  	if (x86_pmu.num_counters > INTEL_PMC_MAX_GENERIC) {
>  		WARN(1, KERN_ERR "hw perf events %d > max(%d), clipping!",
>  		     x86_pmu.num_counters, INTEL_PMC_MAX_GENERIC);


static __init struct attribute **
get_events_attrs(struct attribute **base,
		 struct attribute **mem,
		 struct attribute **tsx)
{
	struct attribute **attrs = base;
	struct attribute **old;

	if (mem) {
		old = attrs;
		attrs = merge_attrs(attrs, mem);
		if (old != base)
			kfree(old);
	}

	if (tsx && boot_cpu_has(X86_FEATURE_RTM)) {
		old = attrs;
		attrs = merge_attrs(attrs, tsx);
		if (old != base)
			kfree(old);
	}

	return attrs;
}

Would that not help to concentrate things a little more?