Date: Mon, 5 Jan 2015 19:57:22 -0800 From: Kevin Oberman <rkoberman@gmail.com> To: Sean Bruno <sbruno@freebsd.org> Cc: "freebsd-acpi@freebsd.org" <freebsd-acpi@freebsd.org> Subject: Re: Haswell, i3, fail to acpi_throttle fail Message-ID: <CAN6yY1vnSLi7%2B0beSSC5awJtZ%2Bt4iWBOcery8Z%2Bt=Wki9LyJBg@mail.gmail.com> In-Reply-To: <54AB32AD.1070409@ignoranthack.me> References: <54AB32AD.1070409@ignoranthack.me>
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On Mon, Jan 5, 2015 at 4:56 PM, Sean Bruno <sbruno@ignoranthack.me> wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA512 > > acpi_throttle0: <ACPI CPU Throttling> on cpu0 > acpi_throttle0: P_CNT from P_BLK 0x1810 > est0: <Enhanced SpeedStep Frequency Control> on cpu0 > acpi_throttle1: <ACPI CPU Throttling> on cpu1 > acpi_throttle1: failed to attach P_CNT > device_attach: acpi_throttle1 attach returned 6 > est1: <Enhanced SpeedStep Frequency Control> on cpu1 > acpi_throttle2: <ACPI CPU Throttling> on cpu2 > acpi_throttle2: failed to attach P_CNT > device_attach: acpi_throttle2 attach returned 6 > est2: <Enhanced SpeedStep Frequency Control> on cpu2 > acpi_throttle3: <ACPI CPU Throttling> on cpu3 > acpi_throttle3: failed to attach P_CNT > device_attach: acpi_throttle3 attach returned 6 > est3: <Enhanced SpeedStep Frequency Control> on cpu3 > > > The call to acpi_bus_alloc_gas() in acpi_throttle.c seems to be failing > to attach. What should I be poking at here? > Excellent! Throttling is counter-productive and always has been. It's been at least 5 years since mav@ posted his excellent wiki article on power management which demonstrated the futility of throttling. More important, even if it was useful for power management, it has long since been superseded by TCC. Intel tried to make the purpose of TCC clear by the name: Thermal Control Circuit. So it is ineffective for power management and FreeBSD still tries to use it. Looks like the vendor broke ACPI so throttling won't work. Or, maybe, Intel simply removed it as unused legacy. Don't worry. Be happy! Make sure that hint.acpi_throttle.0.disabled=1 is set in /boot/loader.conf to disable it. I'd strongly urge that you also disable P4TCC with hint.p4tcc.0.disabled=1. It will trivially improve battery life and will seriously compromise performance if powerd is enabled. It can also cause hangs with elevated C-states on some systems. If you really want to improve battery life with minimal impact on performance, set both performance_cx_lowest and economy_cx_lowest to "Cmax" in rc,conf. No other technique is more effective in saving power than C-states. EST helps, too, but not nearly so much and with a greater impact on performance. If you have not read it, read the wiki article at https://duckduckgo.com/l/?kh=-1&uddg=https%3A%2F%2Fwiki.freebsd.org%2FTuningPowerConsumption -- R. Kevin Oberman, Network Engineer, Retired E-mail: rkoberman@gmail.com
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