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From: Ganapatrao Prabhakerrao Kulkarni <gkulkarni@marvell.com>
To: "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Cc: "peterz@infradead.org" <peterz@infradead.org>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"will@kernel.org" <will@kernel.org>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"corbet@lwn.net" <corbet@lwn.net>,
	"gklkml16@gmail.com" <gklkml16@gmail.com>
Subject: [PATCH 2/2] Thunderx2, uncore: Add workaround for ThunderX2 erratum 221
Date: Wed, 6 Nov 2019 01:01:41 +0000	[thread overview]
Message-ID: <1573002091-9744-3-git-send-email-gkulkarni@marvell.com> (raw)
In-Reply-To: <1573002091-9744-1-git-send-email-gkulkarni@marvell.com>

When perf tried with more events than the PMU supported counters, the perf
core uses event multiplexing to accommodate all events. This results in
burst of PMU register read and writes and causes the system hang, when
executed along with the CPU intensive applications.

Adding software workaround by disabling event multiplexing.

Signed-off-by: Ganapatrao Prabhakerrao Kulkarni <gkulkarni@marvell.com>
---
 Documentation/admin-guide/perf/thunderx2-pmu.rst | 9 +++++++++
 drivers/perf/thunderx2_pmu.c                     | 3 ++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/perf/thunderx2-pmu.rst b/Documentation/admin-guide/perf/thunderx2-pmu.rst
index 08e33675853a..fff65382c887 100644
--- a/Documentation/admin-guide/perf/thunderx2-pmu.rst
+++ b/Documentation/admin-guide/perf/thunderx2-pmu.rst
@@ -40,3 +40,12 @@ Examples::
   uncore_l3c_0/read_hit/,\
   uncore_l3c_0/inv_request/,\
   uncore_l3c_0/inv_hit/ sleep 1
+
+ThunderX2 erratum 221:
+When perf tried with more events than the PMU supported counters, the perf core
+uses event multiplexing to accommodate all events. This results in burst of PMU
+registers read and write and leading to system hang when executed along with
+CPU intensive applications.
+
+
+Disabling PMUs event multiplexing capability.
diff --git a/drivers/perf/thunderx2_pmu.c b/drivers/perf/thunderx2_pmu.c
index 43d76c85da56..c443be8bd449 100644
--- a/drivers/perf/thunderx2_pmu.c
+++ b/drivers/perf/thunderx2_pmu.c
@@ -563,7 +563,8 @@ static int tx2_uncore_pmu_register(
 		.start		= tx2_uncore_event_start,
 		.stop		= tx2_uncore_event_stop,
 		.read		= tx2_uncore_event_read,
-		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
+		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE |
+					PERF_PMU_CAP_NO_MUX_EVENTS,
 	};
 
 	tx2_pmu->pmu.name = devm_kasprintf(dev, GFP_KERNEL,
-- 
2.17.1


WARNING: multiple messages have this Message-ID (diff)
From: Ganapatrao Prabhakerrao Kulkarni <gkulkarni@marvell.com>
To: "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
	"corbet@lwn.net" <corbet@lwn.net>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"gklkml16@gmail.com" <gklkml16@gmail.com>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"will@kernel.org" <will@kernel.org>
Subject: [PATCH 2/2] Thunderx2, uncore: Add workaround for ThunderX2 erratum 221
Date: Wed, 6 Nov 2019 01:01:41 +0000	[thread overview]
Message-ID: <1573002091-9744-3-git-send-email-gkulkarni@marvell.com> (raw)
In-Reply-To: <1573002091-9744-1-git-send-email-gkulkarni@marvell.com>

When perf tried with more events than the PMU supported counters, the perf
core uses event multiplexing to accommodate all events. This results in
burst of PMU register read and writes and causes the system hang, when
executed along with the CPU intensive applications.

Adding software workaround by disabling event multiplexing.

Signed-off-by: Ganapatrao Prabhakerrao Kulkarni <gkulkarni@marvell.com>
---
 Documentation/admin-guide/perf/thunderx2-pmu.rst | 9 +++++++++
 drivers/perf/thunderx2_pmu.c                     | 3 ++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/perf/thunderx2-pmu.rst b/Documentation/admin-guide/perf/thunderx2-pmu.rst
index 08e33675853a..fff65382c887 100644
--- a/Documentation/admin-guide/perf/thunderx2-pmu.rst
+++ b/Documentation/admin-guide/perf/thunderx2-pmu.rst
@@ -40,3 +40,12 @@ Examples::
   uncore_l3c_0/read_hit/,\
   uncore_l3c_0/inv_request/,\
   uncore_l3c_0/inv_hit/ sleep 1
+
+ThunderX2 erratum 221:
+When perf tried with more events than the PMU supported counters, the perf core
+uses event multiplexing to accommodate all events. This results in burst of PMU
+registers read and write and leading to system hang when executed along with
+CPU intensive applications.
+
+
+Disabling PMUs event multiplexing capability.
diff --git a/drivers/perf/thunderx2_pmu.c b/drivers/perf/thunderx2_pmu.c
index 43d76c85da56..c443be8bd449 100644
--- a/drivers/perf/thunderx2_pmu.c
+++ b/drivers/perf/thunderx2_pmu.c
@@ -563,7 +563,8 @@ static int tx2_uncore_pmu_register(
 		.start		= tx2_uncore_event_start,
 		.stop		= tx2_uncore_event_stop,
 		.read		= tx2_uncore_event_read,
-		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
+		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE |
+					PERF_PMU_CAP_NO_MUX_EVENTS,
 	};
 
 	tx2_pmu->pmu.name = devm_kasprintf(dev, GFP_KERNEL,
-- 
2.17.1


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  parent reply	other threads:[~2019-11-06  1:02 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06  1:01 [PATCH 0/2] Workaround for ThunderX2 erratum 221 Ganapatrao Prabhakerrao Kulkarni
2019-11-06  1:01 ` Ganapatrao Prabhakerrao Kulkarni
2019-11-06  1:01 ` [PATCH 1/2] perf/core: Adding capability to disable PMUs event multiplexing Ganapatrao Prabhakerrao Kulkarni
2019-11-06  1:01   ` Ganapatrao Prabhakerrao Kulkarni
2019-11-06  9:40   ` Peter Zijlstra
2019-11-06  9:40     ` Peter Zijlstra
2019-11-06  9:58     ` Peter Zijlstra
2019-11-06  9:58       ` Peter Zijlstra
2019-11-06 11:28   ` Mark Rutland
2019-11-06 11:28     ` Mark Rutland
2019-11-06 23:28     ` Ganapatrao Kulkarni
2019-11-06 23:28       ` Ganapatrao Kulkarni
2019-11-07 14:35       ` Ganapatrao Kulkarni
2019-11-07 14:35         ` Ganapatrao Kulkarni
2019-11-07 14:52       ` Mark Rutland
2019-11-07 14:52         ` Mark Rutland
2019-11-07 15:45         ` Ganapatrao Kulkarni
2019-11-07 15:45           ` Ganapatrao Kulkarni
2019-11-07 15:54           ` Mark Rutland
2019-11-07 15:54             ` Mark Rutland
2019-11-07 15:04       ` Peter Zijlstra
2019-11-07 15:04         ` Peter Zijlstra
2019-11-07 23:17   ` kbuild test robot
2019-11-07 23:17     ` kbuild test robot
2019-11-07 23:17     ` kbuild test robot
2019-11-06  1:01 ` Ganapatrao Prabhakerrao Kulkarni [this message]
2019-11-06  1:01   ` [PATCH 2/2] Thunderx2, uncore: Add workaround for ThunderX2 erratum 221 Ganapatrao Prabhakerrao Kulkarni
2019-11-06 11:37   ` Mark Rutland
2019-11-06 11:37     ` Mark Rutland

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