Re: [PATCH v7 16/26] PM / devfreq: rockchip-dfi: Add perf support

From: Chanwoo Choi
Date: Sun Oct 08 2023 - 17:49:09 EST

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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@xxxxxxxxxxxxxx>
> Reviewed-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>
> ---
>
> 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.

> {
> 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,
> };
>
> +#ifdef CONFIG_PERF_EVENTS
> +
> +static ssize_t ddr_perf_cpumask_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct pmu *pmu = dev_get_drvdata(dev);
> + struct rockchip_dfi *dfi = container_of(pmu, struct rockchip_dfi, pmu);
> +
> + return cpumap_print_to_pagebuf(true, buf, cpumask_of(dfi->cpu));
> +}
> +
> +static struct device_attribute ddr_perf_cpumask_attr =
> + __ATTR(cpumask, 0444, ddr_perf_cpumask_show, NULL);
> +
> +static struct attribute *ddr_perf_cpumask_attrs[] = {
> + &ddr_perf_cpumask_attr.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group ddr_perf_cpumask_attr_group = {
> + .attrs = ddr_perf_cpumask_attrs,
> +};
> +
> +PMU_EVENT_ATTR_STRING(cycles, ddr_pmu_cycles, "event="__stringify(PERF_EVENT_CYCLES))
> +
> +#define DFI_PMU_EVENT_ATTR(_name, _var, _str) \
> + PMU_EVENT_ATTR_STRING(_name, _var, _str); \
> + PMU_EVENT_ATTR_STRING(_name.unit, _var##_unit, "MB"); \
> + PMU_EVENT_ATTR_STRING(_name.scale, _var##_scale, "9.536743164e-07")
> +
> +DFI_PMU_EVENT_ATTR(read-bytes0, ddr_pmu_read_bytes0, "event="__stringify(PERF_EVENT_READ_BYTES0));
> +DFI_PMU_EVENT_ATTR(write-bytes0, ddr_pmu_write_bytes0, "event="__stringify(PERF_EVENT_WRITE_BYTES0));
> +
> +DFI_PMU_EVENT_ATTR(read-bytes1, ddr_pmu_read_bytes1, "event="__stringify(PERF_EVENT_READ_BYTES1));
> +DFI_PMU_EVENT_ATTR(write-bytes1, ddr_pmu_write_bytes1, "event="__stringify(PERF_EVENT_WRITE_BYTES1));
> +
> +DFI_PMU_EVENT_ATTR(read-bytes2, ddr_pmu_read_bytes2, "event="__stringify(PERF_EVENT_READ_BYTES2));
> +DFI_PMU_EVENT_ATTR(write-bytes2, ddr_pmu_write_bytes2, "event="__stringify(PERF_EVENT_WRITE_BYTES2));
> +
> +DFI_PMU_EVENT_ATTR(read-bytes3, ddr_pmu_read_bytes3, "event="__stringify(PERF_EVENT_READ_BYTES3));
> +DFI_PMU_EVENT_ATTR(write-bytes3, ddr_pmu_write_bytes3, "event="__stringify(PERF_EVENT_WRITE_BYTES3));
> +
> +DFI_PMU_EVENT_ATTR(read-bytes, ddr_pmu_read_bytes, "event="__stringify(PERF_EVENT_READ_BYTES));
> +DFI_PMU_EVENT_ATTR(write-bytes, ddr_pmu_write_bytes, "event="__stringify(PERF_EVENT_WRITE_BYTES));
> +
> +DFI_PMU_EVENT_ATTR(bytes, ddr_pmu_bytes, "event="__stringify(PERF_EVENT_BYTES));
> +
> +#define DFI_ATTR_MB(_name) \
> + &_name.attr.attr, \
> + &_name##_unit.attr.attr, \
> + &_name##_scale.attr.attr
> +
> +static struct attribute *ddr_perf_events_attrs[] = {
> + &ddr_pmu_cycles.attr.attr,
> + DFI_ATTR_MB(ddr_pmu_read_bytes),
> + DFI_ATTR_MB(ddr_pmu_write_bytes),
> + DFI_ATTR_MB(ddr_pmu_read_bytes0),
> + DFI_ATTR_MB(ddr_pmu_write_bytes0),
> + DFI_ATTR_MB(ddr_pmu_read_bytes1),
> + DFI_ATTR_MB(ddr_pmu_write_bytes1),
> + DFI_ATTR_MB(ddr_pmu_read_bytes2),
> + DFI_ATTR_MB(ddr_pmu_write_bytes2),
> + DFI_ATTR_MB(ddr_pmu_read_bytes3),
> + DFI_ATTR_MB(ddr_pmu_write_bytes3),
> + DFI_ATTR_MB(ddr_pmu_bytes),
> + NULL,
> +};
> +
> +static const struct attribute_group ddr_perf_events_attr_group = {
> + .name = "events",
> + .attrs = ddr_perf_events_attrs,
> +};
> +
> +PMU_FORMAT_ATTR(event, "config:0-7");
> +
> +static struct attribute *ddr_perf_format_attrs[] = {
> + &format_attr_event.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group ddr_perf_format_attr_group = {
> + .name = "format",
> + .attrs = ddr_perf_format_attrs,
> +};
> +
> +static const struct attribute_group *attr_groups[] = {
> + &ddr_perf_events_attr_group,
> + &ddr_perf_cpumask_attr_group,
> + &ddr_perf_format_attr_group,
> + NULL,
> +};
> +
> +static int rockchip_ddr_perf_event_init(struct perf_event *event)
> +{
> + struct rockchip_dfi *dfi = container_of(event->pmu, struct rockchip_dfi, pmu);
> +
> + if (event->attr.type != event->pmu->type)
> + return -ENOENT;
> +
> + if (event->attach_state & PERF_ATTACH_TASK)
> + return -EINVAL;
> +
> + if (event->cpu < 0) {
> + dev_warn(dfi->dev, "Can't provide per-task data!\n");
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +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'.

> + int i;
> +
> + rockchip_dfi_read_counters(dfi, &now);
> +
> + do {
> + seq = read_seqbegin(&dfi->count_seqlock);
> +
> + rockchip_ddr_perf_counters_add(dfi, &now, &total);
> +

Remove unneeded blank line.

> + } while (read_seqretry(&dfi->count_seqlock, seq));
(snip)

I added the some comment. If you are fixing the comment, feel free to add my ack.
Acked-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>

--
Best Regards,
Samsung Electronics
Chanwoo Choi

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