minit

commit ac7f80097bf46a3d889778fbc62b422258bfe34e
parent 06e88f445336e2732ccd423178d808df64661483
Author: leitner <leitner>
Date:   Mon, 13 Apr 2015 18:30:19 +0000

  add governor (demo tool to set CPU frequency governor based on AC state,
    not actually needed anymore with current hardware, not actually installed)

Diffstat:
M
.cvsignore
 | 
2
++
M
CHANGES
 | 
2
++
A
governor.c
 | 
83
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 87 insertions(+), 0 deletions(-)
diff --git a/.cvsignore b/.cvsignore
@@ -11,3 +11,5 @@ serdo
 ftrigger
 waitinterface
 waitport
+powersave
+governor
diff --git a/CHANGES b/CHANGES
@@ -12,6 +12,8 @@
   add ftrigger (run a command if a file changes)
   add waitinterface and waitport (to resolve races)
   add powersave (demo tool to set up power saving, needs customization, not actually installed)
+  add governor (demo tool to set CPU frequency governor based on AC state,
+    not actually needed anymore with current hardware, not actually installed)
 
 0.10:
   add sample script for /etc/minit/ctrlaltdel/run as
diff --git a/governor.c b/governor.c
@@ -0,0 +1,83 @@
+#include <unistd.h>
+#include <errmsg.h>
+#include <string.h>
+#include <fcntl.h>
+
+const char acstate[]="/proc/acpi/ac_adapter/AC/state";
+const char sysacstate[]="/sys/class/power_supply/AC/online";
+char governor[]="/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor";
+const char powersave[]="powersave";
+const char performance[]="performance";
+const char ondemand[]="conservative";
+
+int main(int argc,char* argv[]) {
+  char buf[1024];
+  int fd,r;
+  const char* s;
+  errmsg_iam("switch_governor");
+
+  if (argc<1)
+    s="governor";
+  else if ((s=strrchr(argv[0],'/')))
+    ++s;
+  else
+    s=argv[0];
+  if (!strcmp(s,"slow")) {
+    s=powersave; goto writeit;
+  } else if (!strcmp(s,"fast")) {
+    s=performance; goto writeit;
+  } else if (!strcmp(s,"auto")) {
+    s=ondemand; goto writeit;
+  }
+
+  /* first try /sys, if that fails attempt /proc */
+  if ((fd=open(sysacstate,O_RDONLY))==-1) {
+    if ((fd=open(acstate,O_RDONLY))==-1)
+      diesys(1,"could not open ",acstate);
+    if ((r=read(fd,buf,sizeof(buf)))<1)
+      diesys(1,"read error");
+    if (r>1000)
+      die(1,"too much data in ",acstate);
+    buf[r]=0;
+    close(fd);
+    if (strstr(buf,"off-line"))
+      s=powersave;
+    else if (strstr(buf,"on-line"))
+      s=ondemand;
+    else
+      die(1,"ac adapter neither on-line nor off-line!?");
+  } else {
+    if ((r=read(fd,buf,sizeof(buf)))<1)
+      diesys(1,"read error");
+    if (r>2)
+      die(1,"too much data in ",sysacstate);
+    buf[r]=0;
+    close(fd);
+    if (buf[0]=='0')
+      s=powersave;
+    else if (buf[0]=='1')
+      s=ondemand;
+    else
+      die(1,"ac adapter neither on-line nor off-line!?");
+  }
+writeit:
+  {
+    int i;
+    char* x=strstr(governor,"cpu0");
+    if (x) x+=3;
+    for (i=0; i<32; ++i) {
+      if ((fd=open(governor,O_WRONLY))==-1) {
+	if (x && *x=='0')
+	  diesys(1,"could not open ",governor);
+	break;
+      }
+      r=strlen(s);
+      if (write(fd,s,r)!=r)
+	diesys(1,"write error");
+      close(fd);
+      if (x) ++(*x); else break;
+    }
+  }
+  carp("switched cpufreq governor to ",s);
+  return 0;
+}