I have a Dell Inspiron i7559 laptop with a Core i5-6300 HQ and an NVIDIA GTX960M GPU. I have installed Ubuntu 15.04 on it, and I've been noticing that the CPU performance is much slower than I expected, especially when I run make even when using all four threads. Lintian takes extremely long amounts of time when checking packages etc.

So I downloaded Super Pi and ran a single threaded benchmark. For 1M digits of pi, it takes 25-26 seconds, whereas my Windows install on the same computer takes 12-13 seconds. Under load, indicator-cpufreq only shows 0.76 GHz.

Something is also off with cpufreq-info, it reports steps of 1 MHz and 759 MHz? That doesn't make sense to me; here's the report for CPU0:

analyzing CPU 0:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 10.0 us.
  hardware limits: 1000 kHz - 759 MHz
  available frequency steps: 759 MHz, 1000 kHz
  available cpufreq governors: conservative, ondemand, userspace, powersave, performance
  current policy: frequency should be within 1000 kHz and 759 MHz.
                  The governor "ondemand" may decide which speed to use
                  within this range.
  current CPU frequency is 1000 kHz.
  cpufreq stats: 759 MHz:19.19%, 1000 kHz:80.81%  (673)

This is really a problem for me, and I don't know why this is happening. Any suggestions or pointers would be very helpful, thank you!

EDIT: I ran these

 $ lshw -c cpu
   product: Intel(R) Core(TM) i5-6300HQ CPU @ 2.30GHz
   vendor: Intel Corp.
   physical id: 1
   bus info: cpu@0
   size: 1MHz
   capacity: 759MHz
   width: 64 bits


 $ cat /sys/devices/system/cpu/cpu0/cpufreq/bios_limit

I do not know the implications of "bios_limit", because it works fine in Windows, but is there a way to change this safely so that I can use both the standard 2.3 GHz and the Intel Turbo speeds? Turbo goes up to 3.2 GHz on this one.


One way I was able to fix this was by installing kernel 4.3. Noticed that this issue wasn't happening when I used a 15.10 live disk.

Note: some Nvidia drivers do not work on 4.x kernels, so I had to install mine from ppa:graphics-drivers to make it work.

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