linux-kernel - Re: [PATCH v3 4/7] MIPS: perf: Fix perf with MT counting other threads

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Message-ID: <63a1ca19-6ded-149a-5a61-7464609c691b@mips.com>
Date:   Thu, 17 May 2018 11:35:17 +0100
From:   Matt Redfearn <matt.redfearn@...s.com>
To:     James Hogan <jhogan@...nel.org>
CC:     Ralf Baechle <ralf@...ux-mips.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        <linux-mips@...ux-mips.org>, Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...hat.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: [PATCH v3 4/7] MIPS: perf: Fix perf with MT counting other
 threads

Hi James,

On 16/05/18 18:59, James Hogan wrote:
> On Fri, Apr 20, 2018 at 11:23:06AM +0100, Matt Redfearn wrote:
>> diff --git a/arch/mips/kernel/perf_event_mipsxx.c b/arch/mips/kernel/perf_event_mipsxx.c
>> index 7e2b7d38a774..fe50986e83c6 100644
>> --- a/arch/mips/kernel/perf_event_mipsxx.c
>> +++ b/arch/mips/kernel/perf_event_mipsxx.c
>> @@ -323,7 +323,11 @@ static int mipsxx_pmu_alloc_counter(struct cpu_hw_events *cpuc,
>>   
>>   static void mipsxx_pmu_enable_event(struct hw_perf_event *evt, int idx)
>>   {
>> +	struct perf_event *event = container_of(evt, struct perf_event, hw);
>>   	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
>> +#ifdef CONFIG_MIPS_MT_SMP
>> +	unsigned int range = evt->event_base >> 24;
>> +#endif /* CONFIG_MIPS_MT_SMP */
>>   
>>   	WARN_ON(idx < 0 || idx >= mipspmu.num_counters);
>>   
>> @@ -331,11 +335,37 @@ static void mipsxx_pmu_enable_event(struct hw_perf_event *evt, int idx)
>>   		(evt->config_base & M_PERFCTL_CONFIG_MASK) |
>>   		/* Make sure interrupt enabled. */
>>   		MIPS_PERFCTRL_IE;
>> -	if (IS_ENABLED(CONFIG_CPU_BMIPS5000))
>> +
>> +#ifdef CONFIG_CPU_BMIPS5000
>> +	{
>>   		/* enable the counter for the calling thread */
>>   		cpuc->saved_ctrl[idx] |=
>>   			(1 << (12 + vpe_id())) | BRCM_PERFCTRL_TC;
>> +	}
>> +#else
>> +#ifdef CONFIG_MIPS_MT_SMP
>> +	if (range > V) {
>> +		/* The counter is processor wide. Set it up to count all TCs. */
>> +		pr_debug("Enabling perf counter for all TCs\n");
>> +		cpuc->saved_ctrl[idx] |= M_TC_EN_ALL;
>> +	} else
>> +#endif /* CONFIG_MIPS_MT_SMP */
>> +	{
>> +		unsigned int cpu, ctrl;
>>   
>> +		/*
>> +		 * Set up the counter for a particular CPU when event->cpu is
>> +		 * a valid CPU number. Otherwise set up the counter for the CPU
>> +		 * scheduling this thread.
>> +		 */
>> +		cpu = (event->cpu >= 0) ? event->cpu : smp_processor_id();
>> +
>> +		ctrl = M_PERFCTL_VPEID(cpu_vpe_id(&cpu_data[cpu]));
>> +		ctrl |= M_TC_EN_VPE;
>> +		cpuc->saved_ctrl[idx] |= ctrl;
>> +		pr_debug("Enabling perf counter for CPU%d\n", cpu);
>> +	}
>> +#endif /* CONFIG_CPU_BMIPS5000 */
> 
> I'm not a huge fan of the ifdefery tbh, I don't think it makes it very
> easy to read having a combination of ifs and #ifdefs. I reckon
> IF_ENABLED would be better, perhaps with having the BMIPS5000 case
> return to avoid too much nesting.

OK, I'll try and tidy it up.

Thanks,
Matt

> 
> Otherwise the patch looks okay to me.
> 
> Thanks
> James
>