linux-kernel - Re: [PATCH 1/2] arm64: perf: Move ARMv8 PMU perf event definitions to asm/perf

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Message-ID: <20161110152946.GG4418@leverpostej>
Date:   Thu, 10 Nov 2016 15:29:47 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Wei Huang <wei@...hat.com>
Cc:     Marc Zyngier <marc.zyngier@....com>, kvmarm@...ts.cs.columbia.edu,
        linux-arm-kernel@...ts.infradead.org, shannon.zhao@...aro.org,
        kvm@...r.kernel.org, christoffer.dall@...aro.org,
        drjones@...hat.com, cov@...eaurora.org, will.deacon@....com,
        catalin.marinas@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] arm64: perf: Move ARMv8 PMU perf event definitions
 to asm/perf_event.h

On Thu, Nov 10, 2016 at 09:12:35AM -0600, Wei Huang wrote:
> On 11/10/2016 03:10 AM, Marc Zyngier wrote:
> > On 09/11/16 19:57, Wei Huang wrote:
> >> diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/perf_event.h

> >> +/*
> >> + * ARMv8 PMUv3 Performance Events handling code.
> >> + * Common event types.
> >> + */
> >> +
> >> +/* Required events. */
> >> +#define ARMV8_PMUV3_PERFCTR_SW_INCR				0x00
> >> +#define ARMV8_PMUV3_PERFCTR_L1D_CACHE_REFILL			0x03
> >> +#define ARMV8_PMUV3_PERFCTR_L1D_CACHE				0x04
> >> +#define ARMV8_PMUV3_PERFCTR_BR_MIS_PRED				0x10
> >> +#define ARMV8_PMUV3_PERFCTR_CPU_CYCLES				0x11
> >> +#define ARMV8_PMUV3_PERFCTR_BR_PRED				0x12
> > 
> > In my initial review, I asked for the "required" events to be moved to a
> > shared location. What's the rational for moving absolutely everything?
> 
> I did notice the phrase "required" in the original email. However I
> think it is weird to have two places for a same set of PMU definitions.
> Other developers might think these two are missing if they don't search
> kernel files carefully.
> 
> If Will Deacon and you insist, I can move only two defs to perf_event.h,
> consolidated with the 2nd patch into a single one.

FWIW, my personal preference would be for all the definitions (or at
least all of the ARMV8_PMUV3_* ones) to be in one place.

That said, I don't feel particularly strongly either way, and I'll defer
to Will.

Thanks,
Mark.