On Wednesday, October 21, 2020 2:42:20 PM CEST Julia Lawall wrote: > > On Wed, 21 Oct 2020, Peter Zijlstra wrote: > > > On Wed, Oct 21, 2020 at 01:56:55PM +0200, Julia Lawall wrote: > > > Prior to 5.8, my machine was using intel_pstate and had few background > > > tasks. Thus the problem wasn't visible in practice. Starting with 5.8 > > > the kernel decided that intel_cpufreq would be more appropriate, which > > > introduced kworkers every 0.004 seconds on all cores. > > > > That still doesn't make any sense. Are you running the legacy on-demand > > thing or something? > > > > Rafael, Srinivas, Viresh, how come it defaults to that? > > The relevant commits are 33aa46f252c7, and 39a188b88332 that fixes a small > bug. I have a Intel(R) Xeon(R) CPU E7-8870 v4 @ 2.10GHz that does not > have the HWP feature, even though the cores seemed to be able to change > their frequencies at the hardware level. That's in the range of "turbo" P-states (if a P-state above a certain threshold is requested by the governor, the processor has a license to choose P-states in the range above this threshold by itself). Cheers!
