All of lore.kernel.org
 help / color / mirror / Atom feed
From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: daniel.lezcano@linaro.org, rafael@kernel.org
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	lukasz.luba@arm.com
Subject: [PATCH v4 5/5] powercap/drivers/dtpm: Scale the power with the load
Date: Fri, 12 Mar 2021 14:04:11 +0100	[thread overview]
Message-ID: <20210312130411.29833-5-daniel.lezcano@linaro.org> (raw)
In-Reply-To: <20210312130411.29833-1-daniel.lezcano@linaro.org>

Currently the power consumption is based on the current OPP power
assuming the entire performance domain is fully loaded.

That gives very gross power estimation and we can do much better by
using the load to scale the power consumption.

Use the utilization to normalize and scale the power usage over the
max possible power.

Tested on a rock960 with 2 big CPUS, the power consumption estimation
conforms with the expected one.

Before this change:

~$ ~/dhrystone -t 1 -l 10000&
~$ cat /sys/devices/virtual/powercap/dtpm/dtpm:0/dtpm:0:1/constraint_0_max_power_uw
2260000

After this change:

~$ ~/dhrystone -t 1 -l 10000&
~$ cat /sys/devices/virtual/powercap/dtpm/dtpm:0/dtpm:0:1/constraint_0_max_power_uw
1130000

~$ ~/dhrystone -t 2 -l 10000&
~$ cat /sys/devices/virtual/powercap/dtpm/dtpm:0/dtpm:0:1/constraint_0_max_power_uw
2260000

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
---

V3:
  - Fixed uninitialized 'cpu' in scaled_power_uw()
V2:
  - Replaced cpumask by em_span_cpus
  - Changed 'util' metrics variable types
  - Optimized utilization scaling power computation
  - Renamed parameter name for scale_pd_power_uw()
---
 drivers/powercap/dtpm_cpu.c | 46 +++++++++++++++++++++++++++++++------
 1 file changed, 39 insertions(+), 7 deletions(-)

diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
index 1c6d1e54691f..e120ea239d75 100644
--- a/drivers/powercap/dtpm_cpu.c
+++ b/drivers/powercap/dtpm_cpu.c
@@ -68,27 +68,59 @@ static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
 	return power_limit;
 }
 
+static u64 scale_pd_power_uw(struct cpumask *pd_mask, u64 power)
+{
+	unsigned long max = 0, sum_util = 0;
+	int cpu;
+
+	for_each_cpu_and(cpu, pd_mask, cpu_online_mask) {
+
+		/*
+		 * The capacity is the same for all CPUs belonging to
+		 * the same perf domain, so a single call to
+		 * arch_scale_cpu_capacity() is enough. However, we
+		 * need the CPU parameter to be initialized by the
+		 * loop, so the call ends up in this block.
+		 *
+		 * We can initialize 'max' with a cpumask_first() call
+		 * before the loop but the bits computation is not
+		 * worth given the arch_scale_cpu_capacity() just
+		 * returns a value where the resulting assembly code
+		 * will be optimized by the compiler.
+		 */
+		max = arch_scale_cpu_capacity(cpu);
+		sum_util += sched_cpu_util(cpu, max);
+	}
+
+	/*
+	 * In the improbable case where all the CPUs of the perf
+	 * domain are offline, 'max' will be zero and will lead to an
+	 * illegal operation with a zero division.
+	 */
+	return max ? (power * ((sum_util << 10) / max)) >> 10 : 0;
+}
+
 static u64 get_pd_power_uw(struct dtpm *dtpm)
 {
 	struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 	struct em_perf_domain *pd;
-	struct cpumask cpus;
+	struct cpumask *pd_mask;
 	unsigned long freq;
-	int i, nr_cpus;
+	int i;
 
 	pd = em_cpu_get(dtpm_cpu->cpu);
-	freq = cpufreq_quick_get(dtpm_cpu->cpu);
 
-	cpumask_and(&cpus, cpu_online_mask, to_cpumask(pd->cpus));
-	nr_cpus = cpumask_weight(&cpus);
+	pd_mask = em_span_cpus(pd);
+
+	freq = cpufreq_quick_get(dtpm_cpu->cpu);
 
 	for (i = 0; i < pd->nr_perf_states; i++) {
 
 		if (pd->table[i].frequency < freq)
 			continue;
 
-		return pd->table[i].power *
-			MICROWATT_PER_MILLIWATT * nr_cpus;
+		return scale_pd_power_uw(pd_mask, pd->table[i].power *
+					 MICROWATT_PER_MILLIWATT);
 	}
 
 	return 0;
-- 
2.17.1


      parent reply	other threads:[~2021-03-12 13:10 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-12 13:04 [PATCH v4 1/5] powercap/drivers/dtpm: Encapsulate even more the code Daniel Lezcano
2021-03-12 13:04 ` [PATCH v4 2/5] powercap/drivers/dtpm: Create a registering system Daniel Lezcano
2021-03-27 12:50   ` Greg KH
2021-03-27 19:41     ` Daniel Lezcano
2021-03-28  6:50       ` Greg KH
2021-03-28 11:11         ` Daniel Lezcano
2021-03-28 11:24           ` Greg KH
2021-03-28 16:07             ` Daniel Lezcano
2021-03-28 17:26               ` Greg KH
2021-03-28 18:01                 ` Daniel Lezcano
2021-03-12 13:04 ` [PATCH v4 3/5] powercap/drivers/dtpm: Simplify the dtpm table Daniel Lezcano
2021-03-12 13:04 ` [PATCH v4 4/5] powercap/drivers/dtpm: Use container_of instead of a private data field Daniel Lezcano
2021-03-12 13:04 ` Daniel Lezcano [this message]

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=20210312130411.29833-5-daniel.lezcano@linaro.org \
    --to=daniel.lezcano@linaro.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=lukasz.luba@arm.com \
    --cc=rafael@kernel.org \
    --subject='Re: [PATCH v4 5/5] powercap/drivers/dtpm: Scale the power with the load' \
    /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: link

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.