diff options
author | Chia-I Wu <olvaffe@gmail.com> | 2022-04-16 03:33:14 +0300 |
---|---|---|
committer | Rob Clark <robdclark@chromium.org> | 2022-04-22 01:05:23 +0300 |
commit | 78f815c1cf8fc5f05dc5cec29eb1895cb53470e9 (patch) | |
tree | 3c57088b050018e3c6726e9350a5b282eaaad615 /drivers/gpu/drm/msm/msm_gpu_devfreq.c | |
parent | 15c411980bacddf294452fd1cf7308b14f3f8c63 (diff) | |
download | linux-78f815c1cf8fc5f05dc5cec29eb1895cb53470e9.tar.xz |
drm/msm: return the average load over the polling period
simple_ondemand interacts poorly with clamp_to_idle. It only looks at
the load since the last get_dev_status call, while it should really look
at the load over polling_ms. When clamp_to_idle true, it almost always
picks the lowest frequency on active because the gpu is idle between
msm_devfreq_idle/msm_devfreq_active.
This logic could potentially be moved into devfreq core.
Fixes: 7c0ffcd40b16 ("drm/msm/gpu: Respect PM QoS constraints")
Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Cc: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20220416003314.59211-3-olvaffe@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>
Diffstat (limited to 'drivers/gpu/drm/msm/msm_gpu_devfreq.c')
-rw-r--r-- | drivers/gpu/drm/msm/msm_gpu_devfreq.c | 60 |
1 files changed, 59 insertions, 1 deletions
diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c index f531015107c3..d2539ca78c29 100644 --- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c +++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c @@ -9,6 +9,7 @@ #include <linux/devfreq.h> #include <linux/devfreq_cooling.h> +#include <linux/math64.h> #include <linux/units.h> /* @@ -75,12 +76,69 @@ static void get_raw_dev_status(struct msm_gpu *gpu, status->busy_time = busy_time; } +static void update_average_dev_status(struct msm_gpu *gpu, + const struct devfreq_dev_status *raw) +{ + struct msm_gpu_devfreq *df = &gpu->devfreq; + const u32 polling_ms = df->devfreq->profile->polling_ms; + const u32 max_history_ms = polling_ms * 11 / 10; + struct devfreq_dev_status *avg = &df->average_status; + u64 avg_freq; + + /* simple_ondemand governor interacts poorly with gpu->clamp_to_idle. + * When we enforce the constraint on idle, it calls get_dev_status + * which would normally reset the stats. When we remove the + * constraint on active, it calls get_dev_status again where busy_time + * would be 0. + * + * To remedy this, we always return the average load over the past + * polling_ms. + */ + + /* raw is longer than polling_ms or avg has no history */ + if (div_u64(raw->total_time, USEC_PER_MSEC) >= polling_ms || + !avg->total_time) { + *avg = *raw; + return; + } + + /* Truncate the oldest history first. + * + * Because we keep the history with a single devfreq_dev_status, + * rather than a list of devfreq_dev_status, we have to assume freq + * and load are the same over avg->total_time. We can scale down + * avg->busy_time and avg->total_time by the same factor to drop + * history. + */ + if (div_u64(avg->total_time + raw->total_time, USEC_PER_MSEC) >= + max_history_ms) { + const u32 new_total_time = polling_ms * USEC_PER_MSEC - + raw->total_time; + avg->busy_time = div_u64( + mul_u32_u32(avg->busy_time, new_total_time), + avg->total_time); + avg->total_time = new_total_time; + } + + /* compute the average freq over avg->total_time + raw->total_time */ + avg_freq = mul_u32_u32(avg->current_frequency, avg->total_time); + avg_freq += mul_u32_u32(raw->current_frequency, raw->total_time); + do_div(avg_freq, avg->total_time + raw->total_time); + + avg->current_frequency = avg_freq; + avg->busy_time += raw->busy_time; + avg->total_time += raw->total_time; +} + static int msm_devfreq_get_dev_status(struct device *dev, struct devfreq_dev_status *status) { struct msm_gpu *gpu = dev_to_gpu(dev); + struct devfreq_dev_status raw; - get_raw_dev_status(gpu, status); + get_raw_dev_status(gpu, &raw); + update_average_dev_status(gpu, &raw); + *status = gpu->devfreq.average_status; return 0; } |