From 538b0188da4653b9f4511a114f014354fb6fb7a5 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 15 Feb 2021 20:24:46 +0100 Subject: cpufreq: ACPI: Set cpuinfo.max_freq directly if max boost is known Commit 3c55e94c0ade ("cpufreq: ACPI: Extend frequency tables to cover boost frequencies") attempted to address a performance issue involving acpi-cpufreq, the schedutil governor and scale-invariance on x86 by extending the frequency tables created by acpi-cpufreq to cover the entire range of "turbo" (or "boost") frequencies, but that caused frequencies reported via /proc/cpuinfo and the scaling_cur_freq attribute in sysfs to change which may confuse users and monitoring tools. For this reason, revert the part of commit 3c55e94c0ade adding the extra entry to the frequency table and use the observation that in principle cpuinfo.max_freq need not be equal to the maximum frequency listed in the frequency table for the given policy. Namely, modify cpufreq_frequency_table_cpuinfo() to allow cpufreq drivers to set their own cpuinfo.max_freq above that frequency and change acpi-cpufreq to set cpuinfo.max_freq to the maximum boost frequency found via CPPC. This should be sufficient to let all of the cpufreq subsystem know the real maximum frequency of the CPU without changing frequency reporting. Link: https://bugzilla.kernel.org/show_bug.cgi?id=211305 Fixes: 3c55e94c0ade ("cpufreq: ACPI: Extend frequency tables to cover boost frequencies") Reported-by: Matt McDonald Tested-by: Matt McDonald Signed-off-by: Rafael J. Wysocki Tested-by: Giovanni Gherdovich Tested-by: Michael Larabel Cc: 5.11+ # 5.11+ --- drivers/cpufreq/freq_table.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'drivers/cpufreq/freq_table.c') diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c index f839dc9852c0..d3f756f7b5a0 100644 --- a/drivers/cpufreq/freq_table.c +++ b/drivers/cpufreq/freq_table.c @@ -52,7 +52,13 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy, } policy->min = policy->cpuinfo.min_freq = min_freq; - policy->max = policy->cpuinfo.max_freq = max_freq; + policy->max = max_freq; + /* + * If the driver has set its own cpuinfo.max_freq above max_freq, leave + * it as is. + */ + if (policy->cpuinfo.max_freq < max_freq) + policy->max = policy->cpuinfo.max_freq = max_freq; if (policy->min == ~0) return -EINVAL; -- cgit v1.2.3