linux-kernel - [PATCH] perf/x86/intel/uncore: Fix the scale of the IMC free-running events

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Date:   Mon, 28 Sep 2020 06:32:40 -0700
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Cc:     ak@...ux.intel.com, Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH] perf/x86/intel/uncore: Fix the scale of the IMC free-running events

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

The "MiB" result of the IMC free-running bandwidth events,
uncore_imc_free_running/read/ and uncore_imc_free_running/write/ are 16
times too small.

The "MiB" value equals the raw IMC free-running bandwidth counter value
times a "scale" which is inaccurate.

The IMC free-running bandwidth events should be incremented per 64B
cache line, not DWs (4 bytes). The "scale" should be 6.103515625e-5.
Fix the "scale" for both Snow Ridge and Ice Lake.

Fixes: 2b3b76b5ec67 ("perf/x86/intel/uncore: Add Ice Lake server uncore support")
Fixes: ee49532b38dd ("perf/x86/intel/uncore: Add IMC uncore support for Snow Ridge")
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 arch/x86/events/intel/uncore_snbep.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 495056fbc273..c3818bfc66a9 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -4804,10 +4804,10 @@ static struct uncore_event_desc snr_uncore_imc_freerunning_events[] = {
 	INTEL_UNCORE_EVENT_DESC(dclk,		"event=0xff,umask=0x10"),
 
 	INTEL_UNCORE_EVENT_DESC(read,		"event=0xff,umask=0x20"),
-	INTEL_UNCORE_EVENT_DESC(read.scale,	"3.814697266e-6"),
+	INTEL_UNCORE_EVENT_DESC(read.scale,	"6.103515625e-5"),
 	INTEL_UNCORE_EVENT_DESC(read.unit,	"MiB"),
 	INTEL_UNCORE_EVENT_DESC(write,		"event=0xff,umask=0x21"),
-	INTEL_UNCORE_EVENT_DESC(write.scale,	"3.814697266e-6"),
+	INTEL_UNCORE_EVENT_DESC(write.scale,	"6.103515625e-5"),
 	INTEL_UNCORE_EVENT_DESC(write.unit,	"MiB"),
 	{ /* end: all zeroes */ },
 };
@@ -5265,17 +5265,17 @@ static struct uncore_event_desc icx_uncore_imc_freerunning_events[] = {
 	INTEL_UNCORE_EVENT_DESC(dclk,			"event=0xff,umask=0x10"),
 
 	INTEL_UNCORE_EVENT_DESC(read,			"event=0xff,umask=0x20"),
-	INTEL_UNCORE_EVENT_DESC(read.scale,		"3.814697266e-6"),
+	INTEL_UNCORE_EVENT_DESC(read.scale,		"6.103515625e-5"),
 	INTEL_UNCORE_EVENT_DESC(read.unit,		"MiB"),
 	INTEL_UNCORE_EVENT_DESC(write,			"event=0xff,umask=0x21"),
-	INTEL_UNCORE_EVENT_DESC(write.scale,		"3.814697266e-6"),
+	INTEL_UNCORE_EVENT_DESC(write.scale,		"6.103515625e-5"),
 	INTEL_UNCORE_EVENT_DESC(write.unit,		"MiB"),
 
 	INTEL_UNCORE_EVENT_DESC(ddrt_read,		"event=0xff,umask=0x30"),
-	INTEL_UNCORE_EVENT_DESC(ddrt_read.scale,	"3.814697266e-6"),
+	INTEL_UNCORE_EVENT_DESC(ddrt_read.scale,	"6.103515625e-5"),
 	INTEL_UNCORE_EVENT_DESC(ddrt_read.unit,		"MiB"),
 	INTEL_UNCORE_EVENT_DESC(ddrt_write,		"event=0xff,umask=0x31"),
-	INTEL_UNCORE_EVENT_DESC(ddrt_write.scale,	"3.814697266e-6"),
+	INTEL_UNCORE_EVENT_DESC(ddrt_write.scale,	"6.103515625e-5"),
 	INTEL_UNCORE_EVENT_DESC(ddrt_write.unit,	"MiB"),
 	{ /* end: all zeroes */ },
 };
-- 
2.17.1