linux-kernel - Re: [PATCH -tip] perf, x86: P4 PMU - check for INSTR

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Date:	Thu, 19 Aug 2010 10:19:00 +0400
From:	Cyrill Gorcunov <gorcunov@...nvz.org>
To:	Lin Ming <ming.m.lin@...el.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Stephane Eranian <eranian@...gle.com>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -tip] perf, x86: P4 PMU - check for INSTR_COMPLETED being
 supported by cpu

On 8/19/10, Lin Ming <ming.m.lin@...el.com> wrote:
> On Thu, 2010-08-19 at 02:54 +0800, Cyrill Gorcunov wrote:
>> INSTR_COMPLETED is supported on particular cpu models of Netburst family,
>> add a check for that.
>>
>> Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
>> CC: Lin Ming <ming.m.lin@...el.com>
>> CC: Stephane Eranian <eranian@...gle.com>
>> CC: Ingo Molnar <mingo@...e.hu>
>> CC: Frédéric Weisbecker <fweisbec@...il.com>
>> CC: Arnaldo Carvalho de Melo <acme@...hat.com>
>> CC: Peter Zijlstra <peterz@...radead.org>
>> ---
>>
>> Hi Ming, please review this patch, and if you happened to have this
>> cpu models give it a try please (if you manage to find some spare time
>> of course). To test it we need RAW event P4_EVENT_INSTR_COMPLETED passed
>> on any model not mentioned in p4_event_match_cpu_model, and reverse ;)
>
> I have model 2 and 6.
>
> int main(int argc, char *argv[])
> {
>         u64 config = ((((P4_EVENT_INSTR_COMPLETED) << 25)   |
>                         ((1ULL) << 9)) << 32)                      |
>                         (0); /* no CCCR needed */
>
> 	printf("%llx\n", config);
> }
>
> Use above code to get the raw config value 5a00020000000000.
>
> 1. Test on model 2 p4, it falls into the check correctly.
>
> # perf top -e r5a00020000000000
>
>   Error: perfcounter syscall returned with -1 (Invalid argument)
>
>   Fatal: No CONFIG_PERF_EVENTS=y kernel support configured?
>
> #dmesg
> P4 PMU: Unsupported event: INSTR_COMPLETED
>
> 2. Test on model 6 p4,
>
> PerfTop:       0 irqs/sec  kernel: nan%  exact:  nan% [1000Hz raw
> 0x5a00020000000000],  (all, 16 CPUs)
>
> It has problem, no data is collected.
>
> I will check this.
>

Thanks Ming, try to set both bogus and bogus bits in event mask
> Lin Ming
>
>>
>>  arch/x86/kernel/cpu/perf_event_p4.c |   30 ++++++++++++++++++++++++++++++
>>  1 file changed, 30 insertions(+)
>>
>> Index: linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c
>> =====================================================================
>> --- linux-2.6.git.orig/arch/x86/kernel/cpu/perf_event_p4.c
>> +++ linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c
>> @@ -350,6 +350,11 @@ static __initconst const u64 p4_hw_cache
>>   },
>>  };
>>
>> +/*
>> + * If general events will ever have a reference to the
>> + * P4_EVENT_INSTR_COMPLETED we would ought to check for
>> + * cpu model match (see how it's done for RAW events)
>> + */
>>  static u64 p4_general_events[PERF_COUNT_HW_MAX] = {
>>    /* non-halted CPU clocks */
>>    [PERF_COUNT_HW_CPU_CYCLES] =
>> @@ -428,6 +433,27 @@ static u64 p4_pmu_event_map(int hw_event
>>  	return config;
>>  }
>>
>> +/* check cpu model specifics */
>> +static bool p4_event_match_cpu_model(unsigned int event_idx)
>> +{
>> +	/* INSTR_COMPLETED event only exist for model 3, 4, 6 (Prescott) */
>> +	if (event_idx == P4_EVENT_INSTR_COMPLETED) {
>> +		if (boot_cpu_data.x86_model	!= 3 &&
>> +			boot_cpu_data.x86_model	!= 4 &&
>> +			boot_cpu_data.x86_model	!= 6) {
>> +			pr_warning("P4 PMU: Unsupported event: INSTR_COMPLETED\n");
>> +			return false;
>> +		}
>> +	}
>> +
>> +	/*
>> +	 * note the IQ_ESCR0, IQ_ESCR1 are available on models 1 and 2
>> +	 * only but since we don't use them at moment -- no check
>> +	 */
>> +
>> +	return true;
>> +}
>> +
>>  static int p4_validate_raw_event(struct perf_event *event)
>>  {
>>  	unsigned int v;
>> @@ -439,6 +465,10 @@ static int p4_validate_raw_event(struct
>>  		return -EINVAL;
>>  	}
>>
>> +	/* it may be unsupported */
>> +	if (!p4_event_match_cpu_model(v))
>> +		return -EINVAL;
>> +
>>  	/*
>>  	 * it may have some screwed PEBS bits
>>  	 */
>
>
>
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