From 6e978b22efa1db9f6e71b24440b5f1d93e968ee3 Mon Sep 17 00:00:00 2001 From: Srinivas Pandruvada Date: Fri, 3 Feb 2017 14:18:39 -0800 Subject: cpufreq: intel_pstate: Disable energy efficiency optimization Some Kabylake desktop processors may not reach max turbo when running in HWP mode, even if running under sustained 100% utilization. This occurs when the HWP.EPP (Energy Performance Preference) is set to "balance_power" (0x80) -- the default on most systems. It occurs because the platform BIOS may erroneously enable an energy-efficiency setting -- MSR_IA32_POWER_CTL BIT-EE, which is not recommended to be enabled on this SKU. On the failing systems, this BIOS issue was not discovered when the desktop motherboard was tested with Windows, because the BIOS also neglects to provide the ACPI/CPPC table, that Windows requires to enable HWP, and so Windows runs in legacy P-state mode, where this setting has no effect. Linux' intel_pstate driver does not require ACPI/CPPC to enable HWP, and so it runs in HWP mode, exposing this incorrect BIOS configuration. There are several ways to address this problem. First, Linux can also run in legacy P-state mode on this system. As intel_pstate is how Linux enables HWP, booting with "intel_pstate=disable" will run in acpi-cpufreq/ondemand legacy p-state mode. Or second, the "performance" governor can be used with intel_pstate, which will modify HWP.EPP to 0. Or third, starting in 4.10, the /sys/devices/system/cpu/cpufreq/policy*/energy_performance_preference attribute in can be updated from "balance_power" to "performance". Or fourth, apply this patch, which fixes the erroneous setting of MSR_IA32_POWER_CTL BIT_EE on this model, allowing the default configuration to function as designed. Signed-off-by: Srinivas Pandruvada Reviewed-by: Len Brown Cc: 4.6+ # 4.6+ Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/intel_pstate.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'drivers') diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index f91c25718d16..86e36544925f 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -1235,6 +1235,25 @@ static void intel_pstate_hwp_enable(struct cpudata *cpudata) cpudata->epp_default = intel_pstate_get_epp(cpudata, 0); } +#define MSR_IA32_POWER_CTL_BIT_EE 19 + +/* Disable energy efficiency optimization */ +static void intel_pstate_disable_ee(int cpu) +{ + u64 power_ctl; + int ret; + + ret = rdmsrl_on_cpu(cpu, MSR_IA32_POWER_CTL, &power_ctl); + if (ret) + return; + + if (!(power_ctl & BIT(MSR_IA32_POWER_CTL_BIT_EE))) { + pr_info("Disabling energy efficiency optimization\n"); + power_ctl |= BIT(MSR_IA32_POWER_CTL_BIT_EE); + wrmsrl_on_cpu(cpu, MSR_IA32_POWER_CTL, power_ctl); + } +} + static int atom_get_min_pstate(void) { u64 value; @@ -1845,6 +1864,11 @@ static const struct x86_cpu_id intel_pstate_cpu_oob_ids[] __initconst = { {} }; +static const struct x86_cpu_id intel_pstate_cpu_ee_disable_ids[] = { + ICPU(INTEL_FAM6_KABYLAKE_DESKTOP, core_params), + {} +}; + static int intel_pstate_init_cpu(unsigned int cpunum) { struct cpudata *cpu; @@ -1875,6 +1899,12 @@ static int intel_pstate_init_cpu(unsigned int cpunum) cpu->cpu = cpunum; if (hwp_active) { + const struct x86_cpu_id *id; + + id = x86_match_cpu(intel_pstate_cpu_ee_disable_ids); + if (id) + intel_pstate_disable_ee(cpunum); + intel_pstate_hwp_enable(cpu); pid_params.sample_rate_ms = 50; pid_params.sample_rate_ns = 50 * NSEC_PER_MSEC; -- cgit v1.2.3