Nicolas Charles <nicolas.charles@normation.com> writes:
> Could it be that your CPUs is warming and throttling? You didn't mention the platform used, so I'm not sure whether
it'sa server or a laptop
Hmm, that's an interesting thought. The OP did say the CPU type,
but according to Intel's spec page for it [1] the difference between
base and turbo frequency is only 4.0 vs 4.2 GHz, which doesn't seem
like enough to explain the results ... unless you suppose it actually
throttled to below base freq, which surely shouldn't happen that fast.
Might be worth watching the CPU frequency while doing the test though.
I was speculating about some OS-level problem myself. Plain old "top"
might be enough to show relevant info if it's in that area.
regards, tom lane
[1]
https://ark.intel.com/content/www/us/en/ark/products/88195/intel-core-i7-6700k-processor-8m-cache-up-to-4-20-ghz.html