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

[Matt Redfearn]

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