linux-kernel - Re: [PATCH 2/3] perf/x86/intel: Add a distinct name for Granite Rapids

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Message-ID: <20240709095647.GH27299@noisy.programming.kicks-ass.net>
Date: Tue, 9 Jul 2024 11:56:47 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: kan.liang@...ux.intel.com
Cc: mingo@...nel.org, acme@...nel.org, namhyung@...nel.org,
	irogers@...gle.com, adrian.hunter@...el.com,
	alexander.shishkin@...ux.intel.com, linux-kernel@...r.kernel.org,
	ak@...ux.intel.com, eranian@...gle.com,
	Ahmad Yasin <ahmad.yasin@...el.com>, stable@...r.kernel.org
Subject: Re: [PATCH 2/3] perf/x86/intel: Add a distinct name for Granite
 Rapids

On Mon, Jul 08, 2024 at 12:33:35PM -0700, kan.liang@...ux.intel.com wrote:
> From: Kan Liang <kan.liang@...ux.intel.com>
> 
> Currently, the Sapphire Rapids and Granite Rapids share the same PMU
> name, sapphire_rapids. Because from the kernel’s perspective, GNR is
> similar to SPR. The only key difference is that they support different
> extra MSRs. The code path and the PMU name are shared.
> 
> However, from end users' perspective, they are quite different. Besides
> the extra MSRs, GNR has a newer PEBS format, supports Retire Latency,
> supports new CPUID enumeration architecture, doesn't required the
> load-latency AUX event, has additional TMA Level 1 Architectural Events,
> etc. The differences can be enumerated by CPUID or the PERF_CAPABILITIES
> MSR. They weren't reflected in the model-specific kernel setup.
> But it is worth to have a distinct PMU name for GNR.
> 
> Fixes: a6742cb90b56 ("perf/x86/intel: Fix the FRONTEND encoding on GNR and MTL")
> Suggested-by: Ahmad Yasin <ahmad.yasin@...el.com>
> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
> Cc: stable@...r.kernel.org
> ---
>  arch/x86/events/intel/core.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index b61367991a16..7a9f931a1f48 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -6943,12 +6943,17 @@ __init int intel_pmu_init(void)
>  	case INTEL_EMERALDRAPIDS_X:
>  		x86_pmu.flags |= PMU_FL_MEM_LOADS_AUX;
>  		x86_pmu.extra_regs = intel_glc_extra_regs;
> +		pr_cont("Sapphire Rapids events, ");
> +		name = "sapphire_rapids";
>  		fallthrough;
>  	case INTEL_GRANITERAPIDS_X:
>  	case INTEL_GRANITERAPIDS_D:
>  		intel_pmu_init_glc(NULL);
> -		if (!x86_pmu.extra_regs)
> +		if (!x86_pmu.extra_regs) {
>  			x86_pmu.extra_regs = intel_rwc_extra_regs;
> +			pr_cont("Granite Rapids events, ");
> +			name = "granite_rapids";
> +		}
>  		x86_pmu.pebs_ept = 1;
>  		x86_pmu.hw_config = hsw_hw_config;
>  		x86_pmu.get_event_constraints = glc_get_event_constraints;
> @@ -6959,8 +6964,6 @@ __init int intel_pmu_init(void)
>  		td_attr = glc_td_events_attrs;
>  		tsx_attr = glc_tsx_events_attrs;
>  		intel_pmu_pebs_data_source_skl(true);
> -		pr_cont("Sapphire Rapids events, ");
> -		name = "sapphire_rapids";
>  		break;

For some reason this didn't want to apply cleanly (something trivial),
but since I had to edit it, my fingers slipped and I ended up with the
below. That ok?

---
Subject: perf/x86/intel: Add a distinct name for Granite Rapids
From: Kan Liang <kan.liang@...ux.intel.com>
Date: Mon, 8 Jul 2024 12:33:35 -0700

From: Kan Liang <kan.liang@...ux.intel.com>

Currently, the Sapphire Rapids and Granite Rapids share the same PMU
name, sapphire_rapids. Because from the kernel’s perspective, GNR is
similar to SPR. The only key difference is that they support different
extra MSRs. The code path and the PMU name are shared.

However, from end users' perspective, they are quite different. Besides
the extra MSRs, GNR has a newer PEBS format, supports Retire Latency,
supports new CPUID enumeration architecture, doesn't required the
load-latency AUX event, has additional TMA Level 1 Architectural Events,
etc. The differences can be enumerated by CPUID or the PERF_CAPABILITIES
MSR. They weren't reflected in the model-specific kernel setup.
But it is worth to have a distinct PMU name for GNR.

Fixes: a6742cb90b56 ("perf/x86/intel: Fix the FRONTEND encoding on GNR and MTL")
Suggested-by: Ahmad Yasin <ahmad.yasin@...el.com>
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: stable@...r.kernel.org
Link: https://lkml.kernel.org/r/20240708193336.1192217-3-kan.liang@linux.intel.com
---
 arch/x86/events/intel/core.c |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -6788,12 +6788,18 @@ __init int intel_pmu_init(void)
 	case INTEL_FAM6_EMERALDRAPIDS_X:
 		x86_pmu.flags |= PMU_FL_MEM_LOADS_AUX;
 		x86_pmu.extra_regs = intel_glc_extra_regs;
-		fallthrough;
+		pr_cont("Sapphire Rapids events, ");
+		name = "sapphire_rapids";
+		goto glc_common;
+
 	case INTEL_FAM6_GRANITERAPIDS_X:
 	case INTEL_FAM6_GRANITERAPIDS_D:
+		x86_pmu.extra_regs = intel_rwc_extra_regs;
+		pr_cont("Granite Rapids events, ");
+		name = "granite_rapids";
+
+	glc_common:
 		intel_pmu_init_glc(NULL);
-		if (!x86_pmu.extra_regs)
-			x86_pmu.extra_regs = intel_rwc_extra_regs;
 		x86_pmu.pebs_ept = 1;
 		x86_pmu.hw_config = hsw_hw_config;
 		x86_pmu.get_event_constraints = glc_get_event_constraints;
@@ -6804,8 +6810,6 @@ __init int intel_pmu_init(void)
 		td_attr = glc_td_events_attrs;
 		tsx_attr = glc_tsx_events_attrs;
 		intel_pmu_pebs_data_source_skl(true);
-		pr_cont("Sapphire Rapids events, ");
-		name = "sapphire_rapids";
 		break;
 
 	case INTEL_FAM6_ALDERLAKE: