From: Chia-I Wu <olvaffe@gmail.com> To: freedreno@lists.freedesktop.org Cc: Rob Clark <robdclark@chromium.org>, David Airlie <airlied@linux.ie>, linux-arm-msm@vger.kernel.org, Abhinav Kumar <quic_abhinavk@quicinc.com>, dri-devel@lists.freedesktop.org, Sean Paul <sean@poorly.run> Subject: [PATCH 3/3] drm/msm: return the average load over the polling period Date: Fri, 15 Apr 2022 17:33:14 -0700 [thread overview] Message-ID: <20220416003314.59211-3-olvaffe@gmail.com> (raw) In-Reply-To: <20220416003314.59211-1-olvaffe@gmail.com> 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> --- drivers/gpu/drm/msm/msm_gpu.h | 3 ++ drivers/gpu/drm/msm/msm_gpu_devfreq.c | 60 ++++++++++++++++++++++++++- 2 files changed, 62 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h index 389c6dab751b..143c56f5185b 100644 --- a/drivers/gpu/drm/msm/msm_gpu.h +++ b/drivers/gpu/drm/msm/msm_gpu.h @@ -9,6 +9,7 @@ #include <linux/adreno-smmu-priv.h> #include <linux/clk.h> +#include <linux/devfreq.h> #include <linux/interconnect.h> #include <linux/pm_opp.h> #include <linux/regulator/consumer.h> @@ -117,6 +118,8 @@ struct msm_gpu_devfreq { /** idle_time: Time of last transition to idle: */ ktime_t idle_time; + struct devfreq_dev_status average_status; + /** * idle_work: * 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; } -- 2.36.0.rc0.470.gd361397f0d-goog
WARNING: multiple messages have this Message-ID (diff)
From: Chia-I Wu <olvaffe@gmail.com> To: freedreno@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, Sean Paul <sean@poorly.run>, Abhinav Kumar <quic_abhinavk@quicinc.com>, David Airlie <airlied@linux.ie>, linux-arm-msm@vger.kernel.org, Daniel Vetter <daniel@ffwll.ch>, Rob Clark <robdclark@chromium.org> Subject: [PATCH 3/3] drm/msm: return the average load over the polling period Date: Fri, 15 Apr 2022 17:33:14 -0700 [thread overview] Message-ID: <20220416003314.59211-3-olvaffe@gmail.com> (raw) In-Reply-To: <20220416003314.59211-1-olvaffe@gmail.com> 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> --- drivers/gpu/drm/msm/msm_gpu.h | 3 ++ drivers/gpu/drm/msm/msm_gpu_devfreq.c | 60 ++++++++++++++++++++++++++- 2 files changed, 62 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h index 389c6dab751b..143c56f5185b 100644 --- a/drivers/gpu/drm/msm/msm_gpu.h +++ b/drivers/gpu/drm/msm/msm_gpu.h @@ -9,6 +9,7 @@ #include <linux/adreno-smmu-priv.h> #include <linux/clk.h> +#include <linux/devfreq.h> #include <linux/interconnect.h> #include <linux/pm_opp.h> #include <linux/regulator/consumer.h> @@ -117,6 +118,8 @@ struct msm_gpu_devfreq { /** idle_time: Time of last transition to idle: */ ktime_t idle_time; + struct devfreq_dev_status average_status; + /** * idle_work: * 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; } -- 2.36.0.rc0.470.gd361397f0d-goog
next prev parent reply other threads:[~2022-04-16 0:33 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-04-16 0:33 [PATCH 1/3] drm/msm: remove explicit devfreq status reset Chia-I Wu 2022-04-16 0:33 ` Chia-I Wu 2022-04-16 0:33 ` [PATCH 2/3] drm/msm: simplify gpu_busy callback Chia-I Wu 2022-04-16 0:33 ` Chia-I Wu 2022-04-16 0:33 ` Chia-I Wu [this message] 2022-04-16 0:33 ` [PATCH 3/3] drm/msm: return the average load over the polling period Chia-I Wu 2022-04-16 0:50 ` Chia-I Wu 2022-04-16 0:50 ` Chia-I Wu
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20220416003314.59211-3-olvaffe@gmail.com \ --to=olvaffe@gmail.com \ --cc=airlied@linux.ie \ --cc=dri-devel@lists.freedesktop.org \ --cc=freedreno@lists.freedesktop.org \ --cc=linux-arm-msm@vger.kernel.org \ --cc=quic_abhinavk@quicinc.com \ --cc=robdclark@chromium.org \ --cc=sean@poorly.run \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.