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Subject[PATCH v4 20/24] PM / devfreq: tegra30: Optimize upper average watermark selection
Date
I noticed that CPU may be crossing the dependency threshold very
frequently for some workloads and this results in a lot of interrupts
which could be avoided if MCALL client is keeping actual EMC frequency
at a higher rate.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
drivers/devfreq/tegra30-devfreq.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
index c3cf87231d25..4d582809acb6 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -314,7 +314,8 @@ static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
}

static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
- struct tegra_devfreq_device *dev)
+ struct tegra_devfreq_device *dev,
+ unsigned long freq)
{
unsigned long avg_threshold, lower, upper;

@@ -323,6 +324,15 @@ static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
avg_threshold = dev->config->avg_dependency_threshold;
avg_threshold = avg_threshold * ACTMON_SAMPLING_PERIOD;

+ /*
+ * If cumulative EMC frequency selection is higher than the
+ * device's, then there is no need to set upper watermark to
+ * a lower value because it will result in unnecessary upper
+ * interrupts.
+ */
+ if (freq * ACTMON_SAMPLING_PERIOD > upper)
+ upper = freq * ACTMON_SAMPLING_PERIOD;
+
/*
* We want to get interrupts when MCCPU client crosses the
* dependency threshold in order to take into / out of account
@@ -392,6 +402,7 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
struct tegra_devfreq_device *dev)
{
u32 intr_status, dev_ctrl, avg_intr_mask, avg_count;
+ unsigned long freq;

trace_device_isr_enter(tegra->regs, dev->config->offset,
dev->boost_freq, cpufreq_get(0));
@@ -405,8 +416,10 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
avg_intr_mask = ACTMON_DEV_INTR_AVG_BELOW_WMARK |
ACTMON_DEV_INTR_AVG_ABOVE_WMARK;

- if (intr_status & avg_intr_mask)
- tegra_devfreq_update_avg_wmark(tegra, dev);
+ if (intr_status & avg_intr_mask) {
+ freq = clk_get_rate(tegra->emc_clock) / KHZ;
+ tegra_devfreq_update_avg_wmark(tegra, dev, freq);
+ }

if (intr_status & ACTMON_DEV_INTR_CONSECUTIVE_UPPER) {
/*
@@ -525,7 +538,7 @@ static int tegra_actmon_clk_notify_cb(struct notifier_block *nb,
for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
dev = &tegra->devices[i];

- tegra_devfreq_update_avg_wmark(tegra, dev);
+ tegra_devfreq_update_avg_wmark(tegra, dev, freq);
tegra_devfreq_update_wmark(tegra, dev, freq);
}

@@ -630,7 +643,7 @@ static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
device_writel(dev, dev->avg_freq * ACTMON_SAMPLING_PERIOD,
ACTMON_DEV_INIT_AVG);

- tegra_devfreq_update_avg_wmark(tegra, dev);
+ tegra_devfreq_update_avg_wmark(tegra, dev, dev->avg_freq);
tegra_devfreq_update_wmark(tegra, dev, dev->avg_freq);

device_writel(dev, ACTMON_COUNT_WEIGHT, ACTMON_DEV_COUNT_WEIGHT);
--
2.22.0
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