linux-kernel - Re: [PATCH V2 04/23] perf/x86/intel: Support adaptive PEBSv4

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Date:   Thu, 21 Mar 2019 22:13:55 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     kan.liang@...ux.intel.com
Cc:     acme@...nel.org, mingo@...hat.com, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, jolsa@...nel.org, eranian@...gle.com,
        alexander.shishkin@...ux.intel.com, ak@...ux.intel.com
Subject: Re: [PATCH V2 04/23] perf/x86/intel: Support adaptive PEBSv4

On Thu, Mar 21, 2019 at 01:56:44PM -0700, kan.liang@...ux.intel.com wrote:
> @@ -1434,20 +1692,20 @@ static void __intel_pmu_pebs_event(struct perf_event *event,
>  		return;
>  
>  	while (count > 1) {
> -		setup_pebs_sample_data(event, iregs, at, &data, &regs);
> -		perf_event_output(event, &data, &regs);
> -		at += x86_pmu.pebs_record_size;
> +		x86_pmu.setup_pebs_sample_data(event, iregs, at, &data, regs);
> +		perf_event_output(event, &data, regs);
> +		at = next_pebs_record(at);
>  		at = get_next_pebs_record_by_bit(at, top, bit);
>  		count--;
>  	}
>  
> -	setup_pebs_sample_data(event, iregs, at, &data, &regs);
> +	x86_pmu.setup_pebs_sample_data(event, iregs, at, &data, regs);

If you make the setup_pebs_sample_data() a function pointer argument of
this function.

>  
>  	/*
>  	 * All but the last records are processed.
>  	 * The last one is left to be able to call the overflow handler.
>  	 */
> -	if (perf_event_overflow(event, &data, &regs)) {
> +	if (perf_event_overflow(event, &data, regs)) {
>  		x86_pmu_stop(event, 0);
>  		return;
>  	}
> @@ -1626,6 +1884,59 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
>  	}
>  }
>  
> +static void intel_pmu_drain_pebs_icl(struct pt_regs *iregs)
> +{
> +	short counts[INTEL_PMC_IDX_FIXED + MAX_FIXED_PEBS_EVENTS] = {};
> +	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
> +	struct debug_store *ds = cpuc->ds;
> +	struct perf_event *event;
> +	void *base, *at, *top;
> +	int bit, size;
> +	u64 mask;
> +
> +	if (!x86_pmu.pebs_active)
> +		return;
> +
> +	base = (struct pebs_basic *)(unsigned long)ds->pebs_buffer_base;
> +	top = (struct pebs_basic *)(unsigned long)ds->pebs_index;
> +
> +	ds->pebs_index = ds->pebs_buffer_base;
> +
> +	mask = ((1ULL << x86_pmu.max_pebs_events) - 1) |
> +	       (((1ULL << x86_pmu.num_counters_fixed) - 1) << INTEL_PMC_IDX_FIXED);
> +	size = INTEL_PMC_IDX_FIXED + x86_pmu.num_counters_fixed;
> +
> +	if (unlikely(base >= top)) {
> +		intel_pmu_pebs_event_update_no_drain(cpuc, size);
> +		return;
> +	}
> +
> +	for (at = base; at < top; at = next_pebs_record(at)) {
> +		u64 pebs_status;
> +
> +		pebs_status = get_pebs_status(at) & cpuc->pebs_enabled;
> +		pebs_status &= mask;
> +
> +		for_each_set_bit(bit, (unsigned long *)&pebs_status, size)
> +			counts[bit]++;
> +	}
> +
> +	for (bit = 0; bit < size; bit++) {
> +		if (counts[bit] == 0)
> +			continue;
> +
> +		event = cpuc->events[bit];
> +		if (WARN_ON_ONCE(!event))
> +			continue;
> +
> +		if (WARN_ON_ONCE(!event->attr.precise_ip))
> +			continue;
> +
> +		__intel_pmu_pebs_event(event, iregs, base,
> +				       top, bit, counts[bit]);

		__intel_pmu_pebs_event(event, iregs, base, top, bit,
				       count[bits], setup_adaptibe_pebs_sample_data);

> +	}
> +}

And we can do away with that x86_pmu method..