Slackware64 14.1.

Having cpu scheduler or timing problem on my end (or something like that). If I run cpu demanding programs like ffmpeg encoding, they don't use %100 cpu and have slow performance. On the other hand, slow performing programs use %100 CPU constantly. I'm guessing this is because I use my own custom kernel with the wrong options; I changed timer to 300hz, I/O scheduler to deadline, and enabled "Automatic Process Group Scheduling".

I have CPU governor to "performance" but it doesn't help. CPU fan normally spins up during heavy cpu load, but this isn't the case with cpu intensive programs (always stays quiet). CPU use remains low. I think I overlooked a kernel option.

Also have slow performance with qemu-kvm. Demanding applications in "Windows 7 guest" don't use %100 cpu but very minimal instead. Oddly, applications that don't need much CPU eat %100 CPU constantly. It's like the CPU frequency governor (or whatever handles this) is working backwards.

What kernel option would cause this?

Any help is greatly appreciated!

You may try setting I/O scheduler to CFQ.