On 19. 7. 8. 오전 7:32, Dmitry Osipenko wrote: > The current implementation is inaccurate and results in very intensive > interrupt activity, which neglects the whole idea of polling offload to > hardware. The reason of the shortcoming is that watermarks are not set > up correctly and this results in ACTMON constantly asking to change freq > and then these requests are ignored. The end result of this patch is that > there are few hundreds of ACTMON's interrupts instead of tens thousands > after few minutes of a working devfreq, meanwhile the transitions activity > stays about the same and governor becomes more reactive. > > Since watermarks are set precisely correct now, the boosting logic is > changed a tad to accommodate the change. The "average sustain coefficient" > multiplier is gone now since there is no need to compensate the improper > watermarks and EMC frequency-bump happens once boosting hits the upper > watermark enough times, depending on the per-device boosting threshold. > > Signed-off-by: Dmitry Osipenko <[email protected]> > --- > drivers/devfreq/tegra30-devfreq.c | 293 +++++++++++++++++++++--------- > 1 file changed, 209 insertions(+), 84 deletions(-) > > diff --git a/drivers/devfreq/tegra30-devfreq.c > b/drivers/devfreq/tegra30-devfreq.c > index 4be7858c33bc..16f7e6cf3b99 100644 > --- a/drivers/devfreq/tegra30-devfreq.c > +++ b/drivers/devfreq/tegra30-devfreq.c > @@ -47,6 +47,8 @@ > > #define ACTMON_DEV_INTR_CONSECUTIVE_UPPER BIT(31) > #define ACTMON_DEV_INTR_CONSECUTIVE_LOWER BIT(30) > +#define ACTMON_DEV_INTR_AVG_BELOW_WMARK BIT(25) > +#define ACTMON_DEV_INTR_AVG_ABOVE_WMARK BIT(24) > > #define ACTMON_ABOVE_WMARK_WINDOW 1 > #define ACTMON_BELOW_WMARK_WINDOW 3 > @@ -63,9 +65,8 @@ > * ACTMON_AVERAGE_WINDOW_LOG2: default value for @DEV_CTRL_K_VAL, which > * translates to 2 ^ (K_VAL + 1). ex: 2 ^ (6 + 1) = 128 > */ > -#define ACTMON_AVERAGE_WINDOW_LOG2 6 > -#define ACTMON_SAMPLING_PERIOD 12 /* ms */ > -#define ACTMON_DEFAULT_AVG_BAND 6 /* 1/10 of % > */ > +#define ACTMON_AVERAGE_WINDOW_LOG2 6 > +#define ACTMON_SAMPLING_PERIOD 12 /* > ms */ > > #define KHZ 1000 > > @@ -142,9 +143,6 @@ struct tegra_devfreq_device { > * watermark breaches. > */ > unsigned long boost_freq; > - > - /* Optimal frequency calculated from the stats for this device */ > - unsigned long target_freq; > }; > > struct tegra_devfreq { > @@ -156,7 +154,6 @@ struct tegra_devfreq { > > struct clk *emc_clock; > unsigned long max_freq; > - unsigned long cur_freq; > struct notifier_block rate_change_nb; > > struct tegra_devfreq_device devices[ARRAY_SIZE(actmon_device_configs)]; > @@ -205,42 +202,182 @@ static unsigned long do_percent(unsigned long val, > unsigned int pct) > return val * pct / 100; > } > > +static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra) > +{ > + struct tegra_actmon_emc_ratio *ratio = actmon_emc_ratios; > + unsigned int cpu_freq = cpufreq_get(0); > + unsigned int i; > + > + for (i = 0; i < ARRAY_SIZE(actmon_emc_ratios); i++, ratio++) { > + if (cpu_freq >= ratio->cpu_freq) { > + if (ratio->emc_freq >= tegra->max_freq) > + return tegra->max_freq; > + else > + return ratio->emc_freq; > + } > + } > + > + return 0; > +} > + > +static unsigned long > +tegra_actmon_account_cpu_freq(struct tegra_devfreq *tegra, > + struct tegra_devfreq_device *dev, > + unsigned long target_freq) > +{ > + unsigned long static_cpu_emc_freq; > + > + if (dev->config->avg_dependency_threshold && > + dev->config->avg_dependency_threshold < dev->avg_count) { > + static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra); > + target_freq = max(target_freq, static_cpu_emc_freq); > + } > + > + return target_freq; > +} > + > +static unsigned long tegra_actmon_lower_freq(struct tegra_devfreq *tegra, > + unsigned long target_freq) > +{ > + unsigned long lower = target_freq; > + struct dev_pm_opp *opp; > + > + opp = dev_pm_opp_find_freq_floor(tegra->devfreq->dev.parent, &lower); > + if (IS_ERR(opp)) > + lower = 0; > + else > + dev_pm_opp_put(opp); > + > + return lower; > +} > + > +static unsigned long tegra_actmon_upper_freq(struct tegra_devfreq *tegra, > + unsigned long target_freq) > +{ > + unsigned long upper = target_freq + 1; > + struct dev_pm_opp *opp; > + > + opp = dev_pm_opp_find_freq_ceil(tegra->devfreq->dev.parent, &upper); > + if (IS_ERR(opp)) > + upper = ULONG_MAX; > + else > + dev_pm_opp_put(opp); > + > + return upper; > +} > + > +static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra, > + struct tegra_devfreq_device *dev, > + unsigned long target_freq, > + unsigned long *lower, > + unsigned long *upper) > +{ > + /* > + * Memory frequencies are guaranteed to have 1MHz granularity > + * and thus we need this rounding down to get a proper watermarks > + * range in a case where target_freq falls into a range of > + * next_possible_opp_freq - 1MHz. > + */ > + target_freq = round_down(target_freq, 1000000); > + > + /* watermarks are set at the borders of the corresponding OPPs */ > + *lower = tegra_actmon_lower_freq(tegra, target_freq); > + *upper = tegra_actmon_upper_freq(tegra, target_freq); > + > + *lower /= KHZ; > + *upper /= KHZ; > + > + /* > + * The upper watermark should take into account CPU's frequency > + * because cpu_to_emc_rate() may override the target_freq with > + * a higher value and thus upper watermark need to be set up > + * accordingly to avoid parasitic upper-events. > + */ > + *upper = tegra_actmon_account_cpu_freq(tegra, dev, *upper); > + > + *lower *= ACTMON_SAMPLING_PERIOD; > + *upper *= ACTMON_SAMPLING_PERIOD; > +} > + > static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra, > struct tegra_devfreq_device *dev) > { > - u32 avg = dev->avg_count; > - u32 avg_band_freq = tegra->max_freq * ACTMON_DEFAULT_AVG_BAND / KHZ; > - u32 band = avg_band_freq * ACTMON_SAMPLING_PERIOD; > + unsigned long lower, upper, freq; > > - device_writel(dev, avg + band, ACTMON_DEV_AVG_UPPER_WMARK); > + freq = dev->avg_count / ACTMON_SAMPLING_PERIOD * KHZ; > + tegra_actmon_get_lower_upper(tegra, dev, freq, &lower, &upper); > > - avg = max(dev->avg_count, band); > - device_writel(dev, avg - band, ACTMON_DEV_AVG_LOWER_WMARK); > + /* > + * We want to get interrupts when MCCPU client crosses the > + * dependency threshold in order to take into / out of account > + * the CPU's freq. > + */ > + if (lower < dev->config->avg_dependency_threshold && > + upper > dev->config->avg_dependency_threshold) { > + if (dev->avg_count < dev->config->avg_dependency_threshold) > + upper = dev->config->avg_dependency_threshold; > + else > + lower = dev->config->avg_dependency_threshold; > + } > + > + device_writel(dev, lower, ACTMON_DEV_AVG_LOWER_WMARK); > + device_writel(dev, upper, ACTMON_DEV_AVG_UPPER_WMARK); > } > > static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra, > - struct tegra_devfreq_device *dev) > + struct tegra_devfreq_device *dev, > + unsigned long freq) > { > - u32 val = tegra->cur_freq * ACTMON_SAMPLING_PERIOD; > + unsigned long lower, upper, delta; > + > + /* > + * Boosting logic kicks-in once lower / upper watermark is hit. > + * The watermarks are based on the updated EMC rate and the > + * average activity. > + * > + * The higher watermark is set in accordance to the EMC rate > + * because we want to set it to the highest mark here and EMC rate > + * represents that mark. The consecutive-upper interrupts are > + * always enabled and we don't want to receive them if they won't > + * do anything useful, hence the upper watermark is capped to maximum. > + * Note that the EMC rate is changed once boosting pushed the rate > + * too high, in that case boosting-up will be stopped because > + * upper watermark is much higher now and it is *important* to > + * stop the unwanted interrupts. > + */ > + tegra_actmon_get_lower_upper(tegra, dev, freq - 1, &lower, &upper); > + > + delta = do_percent(upper - lower, dev->config->boost_up_threshold); > + device_writel(dev, lower + delta, ACTMON_DEV_UPPER_WMARK); > > - device_writel(dev, do_percent(val, dev->config->boost_up_threshold), > - ACTMON_DEV_UPPER_WMARK); > + /* > + * Meanwhile the lower mark is based on the average value > + * because it is the lowest possible consecutive-mark for this > + * device. Once that mark is hit and boosting is stopped, the > + * interrupt is disabled by ISR. > + */ > + freq = dev->avg_count / ACTMON_SAMPLING_PERIOD * KHZ; > + tegra_actmon_get_lower_upper(tegra, dev, freq, &lower, &upper); > > - device_writel(dev, do_percent(val, dev->config->boost_down_threshold), > - ACTMON_DEV_LOWER_WMARK); > + delta = do_percent(upper - lower, dev->config->boost_down_threshold); > + device_writel(dev, lower + delta, ACTMON_DEV_LOWER_WMARK); > } > > static void actmon_isr_device(struct tegra_devfreq *tegra, > struct tegra_devfreq_device *dev) > { > - u32 intr_status, dev_ctrl; > + u32 intr_status, dev_ctrl, avg_intr_mask; > > dev->avg_count = device_readl(dev, ACTMON_DEV_AVG_COUNT); > - tegra_devfreq_update_avg_wmark(tegra, dev); > - > intr_status = device_readl(dev, ACTMON_DEV_INTR_STATUS); > dev_ctrl = device_readl(dev, ACTMON_DEV_CTRL); > > + 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 & ACTMON_DEV_INTR_CONSECUTIVE_UPPER) { > /* > * new_boost = min(old_boost * up_coef + step, max_freq) > @@ -253,8 +390,6 @@ static void actmon_isr_device(struct tegra_devfreq *tegra, > > if (dev->boost_freq >= tegra->max_freq) > dev->boost_freq = tegra->max_freq; > - else > - dev_ctrl |= ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN; > } else if (intr_status & ACTMON_DEV_INTR_CONSECUTIVE_LOWER) { > /* > * new_boost = old_boost * down_coef > @@ -263,63 +398,37 @@ static void actmon_isr_device(struct tegra_devfreq > *tegra, > dev->boost_freq = do_percent(dev->boost_freq, > dev->config->boost_down_coeff); > > - dev_ctrl |= ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN; > - > if (dev->boost_freq < (ACTMON_BOOST_FREQ_STEP >> 1)) > dev->boost_freq = 0; > - else > - dev_ctrl |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN; > } > > - if (dev->config->avg_dependency_threshold) { > - if (dev->avg_count >= dev->config->avg_dependency_threshold) > - dev_ctrl |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN; > - else if (dev->boost_freq == 0) > - dev_ctrl &= ~ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN; > + if (intr_status & avg_intr_mask) { > + /* > + * Once average watermark is hit, it means that the memory > + * activity changed significantly and thus boosting-up shall > + * be reset because EMC clock rate will be changed and > + * boosting will restart in this case. > + */ > + dev->boost_freq = 0; > } > > - device_writel(dev, dev_ctrl, ACTMON_DEV_CTRL); > + /* no boosting => no need for consecutive-down interrupt */ > + if (dev->boost_freq == 0) > + dev_ctrl &= ~ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN; > > + device_writel(dev, dev_ctrl, ACTMON_DEV_CTRL); > device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS); > } > > -static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra, > - unsigned long cpu_freq) > -{ > - unsigned int i; > - struct tegra_actmon_emc_ratio *ratio = actmon_emc_ratios; > - > - for (i = 0; i < ARRAY_SIZE(actmon_emc_ratios); i++, ratio++) { > - if (cpu_freq >= ratio->cpu_freq) { > - if (ratio->emc_freq >= tegra->max_freq) > - return tegra->max_freq; > - else > - return ratio->emc_freq; > - } > - } > - > - return 0; > -} > - > -static void actmon_update_target(struct tegra_devfreq *tegra, > - struct tegra_devfreq_device *dev) > +static unsigned long actmon_update_target(struct tegra_devfreq *tegra, > + struct tegra_devfreq_device *dev) > { > - unsigned long cpu_freq = 0; > - unsigned long static_cpu_emc_freq = 0; > - unsigned int avg_sustain_coef; > - > - if (dev->config->avg_dependency_threshold) { > - cpu_freq = cpufreq_get(0); > - static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq); > - } > + unsigned long target_freq; > > - dev->target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD; > - avg_sustain_coef = 100 * 100 / dev->config->boost_up_threshold; > - dev->target_freq = do_percent(dev->target_freq, avg_sustain_coef); > - dev->target_freq += dev->boost_freq; > + target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD + dev->boost_freq; > + target_freq = tegra_actmon_account_cpu_freq(tegra, dev, target_freq); > > - if (dev->avg_count >= dev->config->avg_dependency_threshold) > - dev->target_freq = max(dev->target_freq, static_cpu_emc_freq); > + return target_freq; > } > > static irqreturn_t actmon_thread_isr(int irq, void *data) > @@ -351,8 +460,8 @@ static int tegra_actmon_rate_notify_cb(struct > notifier_block *nb, > unsigned long action, void *ptr) > { > struct clk_notifier_data *data = ptr; > - struct tegra_devfreq *tegra; > struct tegra_devfreq_device *dev; > + struct tegra_devfreq *tegra; > unsigned int i; > > if (action != POST_RATE_CHANGE) > @@ -360,12 +469,28 @@ static int tegra_actmon_rate_notify_cb(struct > notifier_block *nb, > > tegra = container_of(nb, struct tegra_devfreq, rate_change_nb); > > - tegra->cur_freq = data->new_rate / KHZ; > - > + /* > + * EMC rate could change due to three reasons: > + * > + * 1. Average watermark hit > + * 2. Boosting overflow > + * 3. CPU freq change > + * > + * Once rate is changed, the consecutive watermarks need to be > + * updated in order for boosting to work properly and to avoid > + * unnecessary interrupts. Note that the consecutive range is set for > + * all of devices using the same rate, hence if CPU is doing much > + * less than the other memory clients, then its upper watermark will > + * be very high in comparison to the actual activity (lower watermark) > + * and thus unnecessary upper-interrupts will be suppressed. > + * > + * The average watermarks also should be updated because of 3. > + */ > for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) { > dev = &tegra->devices[i]; > > - tegra_devfreq_update_wmark(tegra, dev); > + tegra_devfreq_update_avg_wmark(tegra, dev); > + tegra_devfreq_update_wmark(tegra, dev, data->new_rate); > } > > return NOTIFY_OK; > @@ -374,15 +499,14 @@ static int tegra_actmon_rate_notify_cb(struct > notifier_block *nb, > static void tegra_actmon_configure_device(struct tegra_devfreq *tegra, > struct tegra_devfreq_device *dev) > { > - u32 val = 0; > - > - dev->target_freq = tegra->cur_freq; > + u32 val = 0, target_freq; > > - dev->avg_count = tegra->cur_freq * ACTMON_SAMPLING_PERIOD; > + target_freq = clk_get_rate(tegra->emc_clock) / KHZ; > + dev->avg_count = target_freq * ACTMON_SAMPLING_PERIOD; > device_writel(dev, dev->avg_count, ACTMON_DEV_INIT_AVG); > > tegra_devfreq_update_avg_wmark(tegra, dev); > - tegra_devfreq_update_wmark(tegra, dev); > + tegra_devfreq_update_wmark(tegra, dev, target_freq); > > device_writel(dev, ACTMON_COUNT_WEIGHT, ACTMON_DEV_COUNT_WEIGHT); > device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS); > @@ -469,13 +593,13 @@ static int tegra_devfreq_get_dev_status(struct device > *dev, > struct tegra_devfreq_device *actmon_dev; > unsigned long cur_freq; > > - cur_freq = READ_ONCE(tegra->cur_freq); > + cur_freq = clk_get_rate(tegra->emc_clock); > > /* To be used by the tegra governor */ > stat->private_data = tegra; > > /* The below are to be used by the other governors */ > - stat->current_frequency = cur_freq * KHZ; > + stat->current_frequency = cur_freq; > > actmon_dev = &tegra->devices[MCALL]; > > @@ -486,7 +610,7 @@ static int tegra_devfreq_get_dev_status(struct device > *dev, > stat->busy_time *= 100 / BUS_SATURATION_RATIO; > > /* Number of cycles in a sampling period */ > - stat->total_time = ACTMON_SAMPLING_PERIOD * cur_freq; > + stat->total_time = cur_freq / KHZ * ACTMON_SAMPLING_PERIOD; > > stat->busy_time = min(stat->busy_time, stat->total_time); > > @@ -505,6 +629,7 @@ static int tegra_governor_get_target(struct devfreq > *devfreq, > struct devfreq_dev_status *stat; > struct tegra_devfreq *tegra; > struct tegra_devfreq_device *dev; > + unsigned long dev_target_freq; > unsigned long target_freq = 0; > unsigned int i; > int err; > @@ -520,9 +645,9 @@ static int tegra_governor_get_target(struct devfreq > *devfreq, > for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) { > dev = &tegra->devices[i]; > > - actmon_update_target(tegra, dev); > + dev_target_freq = actmon_update_target(tegra, dev); > > - target_freq = max(target_freq, dev->target_freq); > + target_freq = max(target_freq, dev_target_freq); > } > > *freq = target_freq * KHZ; > @@ -642,7 +767,6 @@ static int tegra_devfreq_probe(struct platform_device > *pdev) > return rate; > } > > - tegra->cur_freq = clk_get_rate(tegra->emc_clock) / KHZ; > tegra->max_freq = rate / KHZ; > > for (i = 0; i < ARRAY_SIZE(actmon_device_configs); i++) { > @@ -671,7 +795,8 @@ static int tegra_devfreq_probe(struct platform_device > *pdev) > platform_set_drvdata(pdev, tegra); > > tegra->rate_change_nb.notifier_call = tegra_actmon_rate_notify_cb; > - err = clk_notifier_register(tegra->emc_clock, &tegra->rate_change_nb); > + err = clk_notifier_register(tegra->emc_clock, > + &tegra->rate_change_nb); > if (err) { > dev_err(&pdev->dev, > "Failed to register rate change notifier\n"); >
Maybe, it is possible to merge patch4/patch19/patch20 to one patch. -- Best Regards, Chanwoo Choi Samsung Electronics
