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From: Will Deacon <will@kernel.org>
To: Jiucheng Xu <jiucheng.xu@amlogic.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Jianxin Pan <jianxin.pan@amlogic.com>,
	Kelvin Zhang <kelvin.zhang@amlogic.com>,
	Chris Healy <cphealy@gmail.com>, Chris Healy <healych@amazon.com>,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] perf/amlogic: Fix large number of counter issue
Date: Mon, 27 Mar 2023 15:10:55 +0100	[thread overview]
Message-ID: <20230327141054.GC31752@willie-the-truck> (raw)
In-Reply-To: <20230209115403.521868-2-jiucheng.xu@amlogic.com>

On Thu, Feb 09, 2023 at 07:54:02PM +0800, Jiucheng Xu wrote:
> When use 1ms interval, very large number of counter happens
> once in a while as below:
> 
> 25.968654513 281474976710655.84 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/
> 26.118657346 281474976710655.88 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/
> 26.180137180 281474976710655.66 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/
> 
> Root cause is the race between irq handler
> and pmu.read callback. Use spin lock to protect the sw&hw
> counters.
> 
> Signed-off-by: Jiucheng Xu <jiucheng.xu@amlogic.com>
> ---
>  drivers/perf/amlogic/meson_ddr_pmu_core.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/perf/amlogic/meson_ddr_pmu_core.c b/drivers/perf/amlogic/meson_ddr_pmu_core.c
> index 0b24dee1ed3c..9b2e5d5c0626 100644
> --- a/drivers/perf/amlogic/meson_ddr_pmu_core.c
> +++ b/drivers/perf/amlogic/meson_ddr_pmu_core.c
> @@ -14,6 +14,7 @@
>  #include <linux/perf_event.h>
>  #include <linux/platform_device.h>
>  #include <linux/printk.h>
> +#include <linux/spinlock.h>
>  #include <linux/sysfs.h>
>  #include <linux/types.h>
>  
> @@ -23,6 +24,7 @@ struct ddr_pmu {
>  	struct pmu pmu;
>  	struct dmc_info info;
>  	struct dmc_counter counters;	/* save counters from hw */
> +	spinlock_t lock;		/* protect hw/sw counter */
>  	bool pmu_enabled;
>  	struct device *dev;
>  	char *name;
> @@ -92,10 +94,12 @@ static void meson_ddr_perf_event_update(struct perf_event *event)
>  	int idx;
>  	int chann_nr = pmu->info.hw_info->chann_nr;
>  
> +	spin_lock(&pmu->lock);

Why doesn't this need the _irqsave() variant if we're racing with the irq
handler?

Will

_______________________________________________
linux-amlogic mailing list
linux-amlogic@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-amlogic

WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org>
To: Jiucheng Xu <jiucheng.xu@amlogic.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Jianxin Pan <jianxin.pan@amlogic.com>,
	Kelvin Zhang <kelvin.zhang@amlogic.com>,
	Chris Healy <cphealy@gmail.com>, Chris Healy <healych@amazon.com>,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] perf/amlogic: Fix large number of counter issue
Date: Mon, 27 Mar 2023 15:10:55 +0100	[thread overview]
Message-ID: <20230327141054.GC31752@willie-the-truck> (raw)
In-Reply-To: <20230209115403.521868-2-jiucheng.xu@amlogic.com>

On Thu, Feb 09, 2023 at 07:54:02PM +0800, Jiucheng Xu wrote:
> When use 1ms interval, very large number of counter happens
> once in a while as below:
> 
> 25.968654513 281474976710655.84 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/
> 26.118657346 281474976710655.88 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/
> 26.180137180 281474976710655.66 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/
> 
> Root cause is the race between irq handler
> and pmu.read callback. Use spin lock to protect the sw&hw
> counters.
> 
> Signed-off-by: Jiucheng Xu <jiucheng.xu@amlogic.com>
> ---
>  drivers/perf/amlogic/meson_ddr_pmu_core.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/perf/amlogic/meson_ddr_pmu_core.c b/drivers/perf/amlogic/meson_ddr_pmu_core.c
> index 0b24dee1ed3c..9b2e5d5c0626 100644
> --- a/drivers/perf/amlogic/meson_ddr_pmu_core.c
> +++ b/drivers/perf/amlogic/meson_ddr_pmu_core.c
> @@ -14,6 +14,7 @@
>  #include <linux/perf_event.h>
>  #include <linux/platform_device.h>
>  #include <linux/printk.h>
> +#include <linux/spinlock.h>
>  #include <linux/sysfs.h>
>  #include <linux/types.h>
>  
> @@ -23,6 +24,7 @@ struct ddr_pmu {
>  	struct pmu pmu;
>  	struct dmc_info info;
>  	struct dmc_counter counters;	/* save counters from hw */
> +	spinlock_t lock;		/* protect hw/sw counter */
>  	bool pmu_enabled;
>  	struct device *dev;
>  	char *name;
> @@ -92,10 +94,12 @@ static void meson_ddr_perf_event_update(struct perf_event *event)
>  	int idx;
>  	int chann_nr = pmu->info.hw_info->chann_nr;
>  
> +	spin_lock(&pmu->lock);

Why doesn't this need the _irqsave() variant if we're racing with the irq
handler?

Will

WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org>
To: Jiucheng Xu <jiucheng.xu@amlogic.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Jianxin Pan <jianxin.pan@amlogic.com>,
	Kelvin Zhang <kelvin.zhang@amlogic.com>,
	Chris Healy <cphealy@gmail.com>, Chris Healy <healych@amazon.com>,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] perf/amlogic: Fix large number of counter issue
Date: Mon, 27 Mar 2023 15:10:55 +0100	[thread overview]
Message-ID: <20230327141054.GC31752@willie-the-truck> (raw)
In-Reply-To: <20230209115403.521868-2-jiucheng.xu@amlogic.com>

On Thu, Feb 09, 2023 at 07:54:02PM +0800, Jiucheng Xu wrote:
> When use 1ms interval, very large number of counter happens
> once in a while as below:
> 
> 25.968654513 281474976710655.84 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/
> 26.118657346 281474976710655.88 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/
> 26.180137180 281474976710655.66 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/
> 
> Root cause is the race between irq handler
> and pmu.read callback. Use spin lock to protect the sw&hw
> counters.
> 
> Signed-off-by: Jiucheng Xu <jiucheng.xu@amlogic.com>
> ---
>  drivers/perf/amlogic/meson_ddr_pmu_core.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/perf/amlogic/meson_ddr_pmu_core.c b/drivers/perf/amlogic/meson_ddr_pmu_core.c
> index 0b24dee1ed3c..9b2e5d5c0626 100644
> --- a/drivers/perf/amlogic/meson_ddr_pmu_core.c
> +++ b/drivers/perf/amlogic/meson_ddr_pmu_core.c
> @@ -14,6 +14,7 @@
>  #include <linux/perf_event.h>
>  #include <linux/platform_device.h>
>  #include <linux/printk.h>
> +#include <linux/spinlock.h>
>  #include <linux/sysfs.h>
>  #include <linux/types.h>
>  
> @@ -23,6 +24,7 @@ struct ddr_pmu {
>  	struct pmu pmu;
>  	struct dmc_info info;
>  	struct dmc_counter counters;	/* save counters from hw */
> +	spinlock_t lock;		/* protect hw/sw counter */
>  	bool pmu_enabled;
>  	struct device *dev;
>  	char *name;
> @@ -92,10 +94,12 @@ static void meson_ddr_perf_event_update(struct perf_event *event)
>  	int idx;
>  	int chann_nr = pmu->info.hw_info->chann_nr;
>  
> +	spin_lock(&pmu->lock);

Why doesn't this need the _irqsave() variant if we're racing with the irq
handler?

Will

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2023-03-27 14:11 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-09 11:54 [PATCH 1/3] perf/amlogic: Fix config1/config2 parsing issue Jiucheng Xu
2023-02-09 11:54 ` Jiucheng Xu
2023-02-09 11:54 ` Jiucheng Xu
2023-02-09 11:54 ` [PATCH 2/3] perf/amlogic: Fix large number of counter issue Jiucheng Xu
2023-02-09 11:54   ` Jiucheng Xu
2023-02-09 11:54   ` Jiucheng Xu
2023-03-27 14:10   ` Will Deacon [this message]
2023-03-27 14:10     ` Will Deacon
2023-03-27 14:10     ` Will Deacon
2023-03-28  2:29     ` Jiucheng Xu
2023-03-28  2:29       ` Jiucheng Xu
2023-03-28  2:29       ` Jiucheng Xu
2023-03-28 11:55       ` Will Deacon
2023-03-28 11:55         ` Will Deacon
2023-03-28 11:55         ` Will Deacon
2023-02-09 11:54 ` [PATCH 3/3] arm64: defconfig: Add Meson DDR PMU as build-in Jiucheng Xu
2023-02-09 11:54   ` Jiucheng Xu
2023-02-09 11:54   ` Jiucheng Xu
2023-02-10 15:58   ` Chris Healy
2023-02-10 15:58     ` Chris Healy
2023-02-10 15:58     ` Chris Healy
2023-03-27 15:01 ` [PATCH 1/3] perf/amlogic: Fix config1/config2 parsing issue Will Deacon
2023-03-27 15:01   ` Will Deacon
2023-03-27 15:01   ` Will Deacon

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