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cpufreq: intel_pstate: Force HWP min perf before offline 

Force HWP Request MAX = HWP Request MIN = HWP Capability MIN and EPP to
0xFF. In this way the performance limits on the offlined CPU will not
influence performance limits on its sibling CPU, which is still online.

If the sibling CPU is calling for higher performance, it will impact the
max core performance. Here core performance will follow higher of the
performance requests from each sibling.

Reported-and-tested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Srinivas Pandruvada 2018-11-16 14:24:19 -08:00 committed by Rafael J. Wysocki
parent 6e218d21ac
commit af3b7379e2
1 changed files with 26 additions and 2 deletions
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28
drivers/cpufreq/intel_pstate.c
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@ -830,6 +830,28 @@ skip_epp:
wrmsrl_on_cpu(cpu, MSR_HWP_REQUEST, value);
}
static void intel_pstate_hwp_force_min_perf(int cpu)
{
u64 value;
int min_perf;
value = all_cpu_data[cpu]->hwp_req_cached;
value &= ~GENMASK_ULL(31, 0);
min_perf = HWP_LOWEST_PERF(all_cpu_data[cpu]->hwp_cap_cached);
/* Set hwp_max = hwp_min */
value |= HWP_MAX_PERF(min_perf);
value |= HWP_MIN_PERF(min_perf);
/* Set EPP/EPB to min */
if (static_cpu_has(X86_FEATURE_HWP_EPP))
value |= HWP_ENERGY_PERF_PREFERENCE(HWP_EPP_POWERSAVE);
else
intel_pstate_set_epb(cpu, HWP_EPP_BALANCE_POWERSAVE);
wrmsrl_on_cpu(cpu, MSR_HWP_REQUEST, value);
}
static int intel_pstate_hwp_save_state(struct cpufreq_policy *policy)
{
struct cpudata *cpu_data = all_cpu_data[policy->cpu];
@ -2084,10 +2106,12 @@ static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
pr_debug("CPU %d exiting\n", policy->cpu);
intel_pstate_clear_update_util_hook(policy->cpu);
if (hwp_active)
if (hwp_active) {
intel_pstate_hwp_save_state(policy);
else
intel_pstate_hwp_force_min_perf(policy->cpu);
} else {
intel_cpufreq_stop_cpu(policy);
}
}
static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)