Comment 52 for bug 1480349

I wonder if these MSRs are set to the same contents in *all* cores?

Anyway, please look at this:

http://article.gmane.org/gmane.linux.power-management.general/70615/match=msr_ia32_energy_perf_bias

"The assumption that BIOSes never want to have this register being set to
full performance (zero) is wrong.

While wrongly overruling this BIOS setting and set it to from performance
to normal did not hurt that much, because nobody really knew the effects inside
Intel processors.

But with Broadwell-EP processor (E5-2687W v4) the CPU will not enter turbo modes
if this value is not set to performance."

Now, it says "Broadwell-EP E5-2687W v4" in the commit text, but there is no such a beast in Intel ARK, so it might well be the Haswell E5-2687W v3. And even if the commit text is indeed correct, it is likely worth a try to check the behavior of MSR_IA32_ENERGY_PERF_BIAS in the new Haswell microcode...

So, maybe you could try to set MSR_IA32_ENERGY_PERF_BIAS to zero on all cores (maybe using the x86_energy_perf_policy utility, it is in the Linux kernel source tree, at "tools/power/x86/x86_energy_perf_policy"), and check if that fixes the issue as well?