From f38996b3a3c6d05909e5dd61ce1a2c1b5de85c7a Mon Sep 17 00:00:00 2001
From: Timo Wilken
Date: Thu, 2 Mar 2023 15:42:44 +0100
Subject: Control max CPU frequency with cpupower

---
 tw/system/cern.scm | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

(limited to 'tw/system/cern.scm')

diff --git a/tw/system/cern.scm b/tw/system/cern.scm
index 0c05b822..fb767213 100644
--- a/tw/system/cern.scm
+++ b/tw/system/cern.scm
@@ -17,7 +17,8 @@
                      mtools pulseaudio search shells wm xorg)
 
 (use-service-modules admin authentication avahi base cups dbus desktop docker
-                     kerberos linux mcron networking pm ssh syncthing vpn xorg)
+                     kerberos linux mcron networking pm shepherd ssh syncthing
+                     vpn xorg)
 
 (define efi-system-partition          ; /dev/nvme0n1p1
   (uuid "806A-2762" 'fat))
@@ -166,13 +167,25 @@
                         (kdc "cerndc.cern.ch"))))))
 
       ;; At high CPU frequencies, the fan is very loud, starting around 3.5 GHz.
-      (service tlp-service-type
-        (tlp-configuration
-         (energy-perf-policy-on-ac "balance_power")
-         (cpu-scaling-governor-on-ac '("powersave"))
-         (cpu-scaling-max-freq-on-ac 3600000)  ; kHz
-         (cpu-boost-on-ac? #f)
-         (sched-powersave-on-ac? #t)))
+      (simple-service 'cpufreq shepherd-root-service-type
+        (list (shepherd-service
+               (documentation "Limit CPU frequency")
+               (provision '(cpufreq))
+               (one-shot? #t)
+               (start #~(make-system-constructor
+                         #$(file-append cpupower "/bin/cpupower")
+                         " frequency-set --max 3.6GHz"))
+               (stop #~(make-system-constructor
+                        #$(file-append cpupower "/bin/cpupower")
+                        " frequency-set --max 4.8GHz"))
+               (actions
+                (list (shepherd-action
+                       (name 'current)
+                       (documentation "Show the current CPU frequencies.")
+                       (procedure
+                        #~(lambda _
+                            (system* #$(file-append cpupower "/bin/cpupower")
+                                     "frequency-info")))))))))
 
       (service thermald-service-type
         (thermald-configuration
-- 
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