Date: Tue, 10 Mar 2020 10:33:45 -0700 From: Conrad Meyer <cem@freebsd.org> To: Theron <theron.tarigo@gmail.com> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: System clock is slow Message-ID: <CAG6CVpU9ihfz9sSh=2foUzaLkT4sF_iLcNcxaVapMi5NVt6EpA@mail.gmail.com> In-Reply-To: <a2603db8-f3e9-fa9d-b2cf-a80e55dc926e@gmail.com> References: <989cd36a-e015-940a-dfe2-851c6fdf4734@gmail.com> <20200310053833.GD3091@server.rulingia.com> <a2603db8-f3e9-fa9d-b2cf-a80e55dc926e@gmail.com>
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On Tue, Mar 10, 2020 at 9:24 AM Theron <theron.tarigo@gmail.com> wrote: > I had previously used powerd to let the CPU underclock to 700MHz when > idle. Now, I've lost all control over CPU frequency (either by powerd > or by sysctl) since there is some in-kernel cpufreq driver which I can't > figure out how to disable. It's hwpstate_intel(4). You can add 'hint.hwpstate_intel.0.disabled="1"' in loader.conf or device.hints to disable and use est(4), if you prefer. The idea of the device is that hardware can do a better job managing the frequency / power states rapidly than daemons like powerd. But if you like powerd/est, feel free to disable it. Future models of Intel CPU may not provide est(4). If you leave it enabled, you can control the energy efficiency / performance trade-off of hwpstate_intel on a per-core basis (or per-package, if not disabled and hardware supports package-level control) with 'dev.hwpstate_intel.<cpu>.epp=0-100' (sysctl or tunable); the CPU uses this knob to control how biased it is towards low frequency states. 100 is most efficient, 0 is most performant. The default is 50. Best, Conrad
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