Problems with P4 Clockmod and CPU frequency scaling

· by Artem Sidorenko · Read in about 1 min · (81 words)

If you are going to use CPU frequency scaling on P4 you will probably use p4-clockmod and get in trouble with ondemand governor like me. If you try to switch to the ondemand governor you can see following message in dmesg:

ondemand governor failed, too long transition latency of HW, fallback to performance governor


Just change the following string in kernel sources arch/x86/kernel/cpu/cpufreq/p4-clockmod.c like here

old string

policy->cpuinfo.transition_latency = 1000000;

new string

policy->cpuinfo.transition_latency = 10000001;

See also