first commit

Makefile

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+VERSION = 0.0.1
+PREFIX = /usr/local
+MANPREFIX = ${PREFIX}/share/man
+
+undervolt: undervolt.sh
+
+install: undervolt
+	mkdir -p ${DESTDIR}${PREFIX}/bin
+	cp -f undervolt ${DESTDIR}${PREFIX}/bin/undervolt
+	chmod 755 ${DESTDIR}${PREFIX}/bin/undervolt
+# TODO: add a manual page
+#	mkdir -p ${DESTDIR}${MANPREFIX}/man1
+#	sed "s/VERSION/${VERSION}/g" < undervolt.1 > ${DESTDIR}${MANPREFIX}/man1/undervolt.1
+#	chmod 644 ${DESTDIR}${MANPREFIX}/man1/undervolt.1
+
+uninstall:
+	rm -f ${DESTDIR}${PREFIX}/bin/undervolt\
+		${DESTDIR}${MANPREFIX}/man1/undervolt.1
+
+clean:
+	rm -f undervolt

README

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+undervolt
+=========
+
+shell script that uses amdctl[1] and ryzenadj[2] to undervolt and limit the power
+consumption of the CPU.
+
+Only works for AMD Ryzen CPUs.
+Tested on:
+	- Ryzen 5 3500U (Lenovo IdeaPad s540-14API)

undervolt.sh

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+#!/bin/sh -e
+
+# TODO: check for root privileges
+# TODO: check if all the required tools are available
+
+CPUS="$(nproc)"
+GOVERNOR='ondemand'
+# Out your wanted values here
+CORE_SPEED_HZ_P0=2300000  # 2.30GHz slightly over the base (2.10GHz)
+CORE_SPEED_HZ_P1=1450000  # 1.45GHz
+CORE_SPEED_HZ_P2=1000000  # 1.00GHz
+# wanted voltage in millivolts
+VOLTAGE_MV_P0=1125   # this should be stable
+VOLTAGE_MV_P1=900
+VOLTAGE_MV_P2=850
+# Power limits
+SUSTAINED_LIMIT_MW=10000
+SLOW_LIMIT_MW=20000
+# Temperature limits
+MAX_TEMP_C=85
+
+# set cpu frequency scaling driver, use acpi_cpufreq since the ryzen 5 3500u
+# does not support the amd_pstate driver
+# acpi_cpufreq is already the default
+
+# enable cpu frequency boost if available
+echo 1 > /sys/devices/system/cpu/cpufreq/boost
+
+# set governor
+for c in $(seq 0 $((CPUS-1)))
+do
+	echo $GOVERNOR > /sys/devices/system/cpu/"cpu$c"/cpufreq/scaling_governor
+done
+
+#
+# set voltage
+# ===========
+
+
+VID_P0="$(amdctl -u $VOLTAGE_MV_P0 | grep vid | awk '{print $3}')"
+VID_P1="$(amdctl -u $VOLTAGE_MV_P1 | grep vid | awk '{print $3}')"
+VID_P2="$(amdctl -u $VOLTAGE_MV_P2 | grep vid | awk '{print $3}')"
+
+for c in 0 .. $((CPUS-1))
+do
+	amdctl -s -m -c $c -p 0 -v "$VID_P0"
+	amdctl -s -m -c $c -p 1 -v "$VID_P1"
+	amdctl -s -m -c $c -p 2 -v "$VID_P2"
+done
+
+#
+# set frequency
+# =============
+
+# TODO: get this from amdctl
+REFERENCE_CLOCK=100000
+
+DID_P0="$(amdctl -c 0 -p 0 -g | grep -1 CpuDid | sed -n '3p' | awk '{print $4}')"
+DID_P1="$(amdctl -c 0 -p 1 -g | grep -1 CpuDid | sed -n '3p' | awk '{print $4}')"
+DID_P2="$(amdctl -c 0 -p 2 -g | grep -1 CpuDid | sed -n '3p' | awk '{print $4}')"
+
+# FIXME: this is taken from https://github.com/kevinlekiller/amdctl/blob/master/amdctl.c#L988
+#        it would be better to submint a pull request and add an option to
+#        this automatically for each processor family
+FID_P0="$(((CORE_SPEED_HZ_P0*DID_P0)/(REFERENCE_CLOCK*2)))"
+FID_P1="$(((CORE_SPEED_HZ_P1*DID_P1)/(REFERENCE_CLOCK*2)))"
+FID_P2="$(((CORE_SPEED_HZ_P2*DID_P2)/(REFERENCE_CLOCK*2)))"
+
+
+for c in 0 .. $((CPUS-1))
+do
+	amdctl -s -m -c $c -p 0 -f $FID_P0
+	amdctl -s -m -c $c -p 1 -f $FID_P1
+	amdctl -s -m -c $c -p 2 -f $FID_P2
+done
+
+
+#
+# Power Limits
+# ============
+
+ryzenadj --stapm-limit=$SUSTAINED_LIMIT_MW \
+         --tctl-temp=$MAX_TEMP_C           \
+         --slow-limit=$SLOW_LIMIT_MW
+
+
+# TODO: undervolt and overclock slightly the GPU