Sometimes after putting my laptop to sleep it's CPU is locked to the slowest frequency - about 600-700MHz.
My laptop is Dell E6420 with i5-2520m.
Kernel version: 4.6.0-040600-generic.
I first came across this bug in 14.04 release. And now we have 16.04 and it's still there.
I am working on my laptop, everything is fine, quick and smooth. I close the lid, putting my laptop to sleep, disconnect power, it is sleeping on it's battery.
I come back after some time, open the lid. And everything is slow as hell;D
I check cpu frequency using
watch -n 1 'cat /proc/cpuinfo | grep MHz'
and I see all my cores working on ~600Mgz frequency.
I check scaling governors
And I see 'powersave'.
To 'fix' this I have to do something like this
echo 'performance' > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor echo 'performance' > /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor echo 'performance' > /sys/devices/system/cpu/cpu2/cpufreq/scaling_governor echo 'performance' > /sys/devices/system/cpu/cpu3/cpufreq/scaling_governor
After that everything is quick as before.
CPU scaling driver is intel_pstate checked with
I'm tired that I always have run this script. It's like I cannot rely on Ubuntu or my laptop(I don't know whose fault it is) anymore.
Why CPU is slow after sleep. Why does this happen? How to resolve this bug?