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Message-ID: <ff2dd5d9-bf0d-403a-b399-b6ec836ad863@kernel.org>
Date: Tue, 17 Oct 2023 17:35:25 +0900
From: Chanwoo Choi <chanwoo@...nel.org>
To: Sascha Hauer <s.hauer@...gutronix.de>
Cc: linux-rockchip@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org, Heiko Stuebner <heiko@...ech.de>,
Kyungmin Park <kyungmin.park@...sung.com>,
MyungJoo Ham <myungjoo.ham@...sung.com>,
Will Deacon <will@...nel.org>,
Mark Rutland <mark.rutland@....com>, kernel@...gutronix.de,
Michael Riesch <michael.riesch@...fvision.net>,
Robin Murphy <robin.murphy@....com>,
Vincent Legoll <vincent.legoll@...il.com>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
Sebastian Reichel <sebastian.reichel@...labora.com>
Subject: Re: [PATCH v7 16/26] PM / devfreq: rockchip-dfi: Add perf support
On 23. 10. 16. 21:16, Sascha Hauer wrote:
> On Mon, Oct 09, 2023 at 06:48:43AM +0900, Chanwoo Choi wrote:
>> On 23. 7. 4. 18:32, Sascha Hauer wrote:
>>> The DFI is a unit which is suitable for measuring DDR utilization, but
>>> so far it could only be used as an event driver for the DDR frequency
>>> scaling driver. This adds perf support to the DFI driver.
>>>
>>> Usage with the 'perf' tool can look like:
>>>
>>> perf stat -a -e rockchip_ddr/cycles/,\
>>> rockchip_ddr/read-bytes/,\
>>> rockchip_ddr/write-bytes/,\
>>> rockchip_ddr/bytes/ sleep 1
>>>
>>> Performance counter stats for 'system wide':
>>>
>>> 1582524826 rockchip_ddr/cycles/
>>> 1802.25 MB rockchip_ddr/read-bytes/
>>> 1793.72 MB rockchip_ddr/write-bytes/
>>> 3595.90 MB rockchip_ddr/bytes/
>>>
>>> 1.014369709 seconds time elapsed
>>>
>>> perf support has been tested on a RK3568 and a RK3399, the latter with
>>> dual channel DDR.
>>>
>>> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
>>> Reviewed-by: Sebastian Reichel <sebastian.reichel@...labora.com>
>>> ---
>>>
>>> Notes:
>>> Changes since v5:
>>> - Add missing initialization of &dfi->last_perf_count
>>>
>>> Changes since v4:
>>>
>>> - use __stringify to ensure event type definitions and event numbers in sysfs are consistent
>>> - only use 64bit values in structs holding counters
>>> - support monitoring individual DDR channels
>>> - fix return value in rockchip_ddr_perf_event_init(): -EOPNOTSUPP -> -EINVAL
>>> - check for invalid event->attr.config values
>>> - start hrtimer to trigger in one second, not immediately
>>> - use devm_add_action_or_reset()
>>> - add suppress_bind_attrs
>>> - enable DDRMON during probe when perf is enabled
>>> - use a seqlock to protect perf reading the counters from the hrtimer callback modifying them
>>>
>>> drivers/devfreq/event/rockchip-dfi.c | 442 ++++++++++++++++++++++++++-
>>> include/soc/rockchip/rk3399_grf.h | 2 +
>>> include/soc/rockchip/rk3568_grf.h | 1 +
>>> 3 files changed, 440 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/devfreq/event/rockchip-dfi.c b/drivers/devfreq/event/rockchip-dfi.c
>>> index 50e497455dc69..969b62f071b83 100644
>>> --- a/drivers/devfreq/event/rockchip-dfi.c
>>> +++ b/drivers/devfreq/event/rockchip-dfi.c
>>> @@ -16,10 +16,12 @@
>>> #include <linux/regmap.h>
>>> #include <linux/slab.h>
>>> #include <linux/list.h>
>>> +#include <linux/seqlock.h>
>>> #include <linux/of.h>
>>> #include <linux/of_device.h>
>>> #include <linux/bitfield.h>
>>> #include <linux/bits.h>
>>> +#include <linux/perf_event.h>
>>>
>>> #include <soc/rockchip/rockchip_grf.h>
>>> #include <soc/rockchip/rk3399_grf.h>
>>> @@ -41,19 +43,39 @@
>>> DDRMON_CTRL_LPDDR4 | \
>>> DDRMON_CTRL_LPDDR23)
>>>
>>> +#define DDRMON_CH0_WR_NUM 0x20
>>> +#define DDRMON_CH0_RD_NUM 0x24
>>> #define DDRMON_CH0_COUNT_NUM 0x28
>>> #define DDRMON_CH0_DFI_ACCESS_NUM 0x2c
>>> #define DDRMON_CH1_COUNT_NUM 0x3c
>>> #define DDRMON_CH1_DFI_ACCESS_NUM 0x40
>>>
>>> +#define PERF_EVENT_CYCLES 0x0
>>> +#define PERF_EVENT_READ_BYTES 0x1
>>> +#define PERF_EVENT_WRITE_BYTES 0x2
>>> +#define PERF_EVENT_READ_BYTES0 0x3
>>> +#define PERF_EVENT_WRITE_BYTES0 0x4
>>> +#define PERF_EVENT_READ_BYTES1 0x5
>>> +#define PERF_EVENT_WRITE_BYTES1 0x6
>>> +#define PERF_EVENT_READ_BYTES2 0x7
>>> +#define PERF_EVENT_WRITE_BYTES2 0x8
>>> +#define PERF_EVENT_READ_BYTES3 0x9
>>> +#define PERF_EVENT_WRITE_BYTES3 0xa
>>> +#define PERF_EVENT_BYTES 0xb
>>> +#define PERF_ACCESS_TYPE_MAX 0xc
>>> +
>>> /**
>>> * struct dmc_count_channel - structure to hold counter values from the DDR controller
>>> * @access: Number of read and write accesses
>>> * @clock_cycles: DDR clock cycles
>>> + * @read_access: number of read accesses
>>> + * @write_acccess: number of write accesses
>>> */
>>> struct dmc_count_channel {
>>> - u32 access;
>>> - u32 clock_cycles;
>>> + u64 access;
>>> + u64 clock_cycles;
>>> + u64 read_access;
>>> + u64 write_access;
>>> };
>>>
>>> struct dmc_count {
>>> @@ -69,6 +91,11 @@ struct rockchip_dfi {
>>> struct devfreq_event_dev *edev;
>>> struct devfreq_event_desc desc;
>>> struct dmc_count last_event_count;
>>> +
>>> + struct dmc_count last_perf_count;
>>> + struct dmc_count total_count;
>>> + seqlock_t count_seqlock; /* protects last_perf_count and total_count */
>>> +
>>> struct device *dev;
>>> void __iomem *regs;
>>> struct regmap *regmap_pmu;
>>> @@ -77,6 +104,14 @@ struct rockchip_dfi {
>>> struct mutex mutex;
>>> u32 ddr_type;
>>> unsigned int channel_mask;
>>> + enum cpuhp_state cpuhp_state;
>>> + struct hlist_node node;
>>> + struct pmu pmu;
>>> + struct hrtimer timer;
>>> + unsigned int cpu;
>>> + int active_events;
>>> + int burst_len;
>>> + int buswidth[DMC_MAX_CHANNELS];
>>> };
>>>
>>> static int rockchip_dfi_enable(struct rockchip_dfi *dfi)
>>> @@ -145,7 +180,7 @@ static void rockchip_dfi_disable(struct rockchip_dfi *dfi)
>>> mutex_unlock(&dfi->mutex);
>>> }
>>>
>>> -static void rockchip_dfi_read_counters(struct rockchip_dfi *dfi, struct dmc_count *count)
>>> +static void rockchip_dfi_read_counters(struct rockchip_dfi *dfi, struct dmc_count *c)
>>
>> Actually, this change is not related to the patch's role which supports perf.
>> Also, it is better to use 'res' argument name because rockchip_ddr_perf_counters_add()
>> used the 'struct dmc_count *res' argument name.
>
> Indeed the variable rename is not required here and for consistency
> with rockchip_ddr_perf_counters_add() 'res' would be a better name.
>
> Are you fine with renaming 'c' to 'res' in this patch or do you want me
> to make a separate patch from the renaming?
>
>>
>>
>>> {
>>> u32 i;
>>> void __iomem *dfi_regs = dfi->regs;
>>> @@ -153,13 +188,36 @@ static void rockchip_dfi_read_counters(struct rockchip_dfi *dfi, struct dmc_coun
>>> for (i = 0; i < DMC_MAX_CHANNELS; i++) {
>>> if (!(dfi->channel_mask & BIT(i)))
>>> continue;
>>> - count->c[i].access = readl_relaxed(dfi_regs +
>>> + c->c[i].read_access = readl_relaxed(dfi_regs +
>>> + DDRMON_CH0_RD_NUM + i * 20);
>>> + c->c[i].write_access = readl_relaxed(dfi_regs +
>>> + DDRMON_CH0_WR_NUM + i * 20);
>>> + c->c[i].access = readl_relaxed(dfi_regs +
>>> DDRMON_CH0_DFI_ACCESS_NUM + i * 20);
>>> - count->c[i].clock_cycles = readl_relaxed(dfi_regs +
>>> + c->c[i].clock_cycles = readl_relaxed(dfi_regs +
>>> DDRMON_CH0_COUNT_NUM + i * 20);
>>> }
>>> }
>>>
>>> +static void rockchip_ddr_perf_counters_add(struct rockchip_dfi *dfi,
>>> + const struct dmc_count *now,
>>> + struct dmc_count *res)
>>> +{
>>> + const struct dmc_count *last = &dfi->last_perf_count;
>>> + int i;
>>> +
>>> + for (i = 0; i < DMC_MAX_CHANNELS; i++) {
>>> + res->c[i].read_access = dfi->total_count.c[i].read_access +
>>> + (u32)(now->c[i].read_access - last->c[i].read_access);
>>> + res->c[i].write_access = dfi->total_count.c[i].write_access +
>>> + (u32)(now->c[i].write_access - last->c[i].write_access);
>>> + res->c[i].access = dfi->total_count.c[i].access +
>>> + (u32)(now->c[i].access - last->c[i].access);
>>> + res->c[i].clock_cycles = dfi->total_count.c[i].clock_cycles +
>>> + (u32)(now->c[i].clock_cycles - last->c[i].clock_cycles);
>>> + }
>>> +}
>>> +
>>> static int rockchip_dfi_event_disable(struct devfreq_event_dev *edev)
>>> {
>>> struct rockchip_dfi *dfi = devfreq_event_get_drvdata(edev);
>>> @@ -223,6 +281,370 @@ static const struct devfreq_event_ops rockchip_dfi_ops = {
>>> .set_event = rockchip_dfi_set_event,
>>> };
>>>
>
> [...]
>
>>> +static u64 rockchip_ddr_perf_event_get_count(struct perf_event *event)
>>> +{
>>> + struct rockchip_dfi *dfi = container_of(event->pmu, struct rockchip_dfi, pmu);
>>> + int blen = dfi->burst_len;
>>> + struct dmc_count total, now;
>>> + unsigned int seq;
>>> + u64 c = 0;
>>
>> Actually, it is difficult to understand the meaning of 'c' local variable name.
>> Need to use the more clear vairable name instead of 'c'.
>
> 'c' is short for 'count' as in the function name xxx_get_count(). It is
> initialized to 0, filled with values throughout the function and
> returned at the end. Which other name do you suggest?
If c indicats the 'count', better to use 'count' name.
Actually, 'c' is difficult to catch the meaning from just name.
>
> Sascha
>
--
Best Regards,
Samsung Electronics
Chanwoo Choi
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