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| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2022-12-28 22:24:10 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2022-12-30 19:10:02 +0100 |
| commit | 99387b016022c29234c4ebf9abd34358c6e56532 (patch) | |
| tree | 684dc0cf43311e196bd2b08b6a5487c55fe3ad3f /drivers/acpi/processor_perflib.c | |
| parent | c02d5feb6e2f60affc6ba8606d8d614c071e2ba6 (diff) | |
| download | lwn-99387b016022c29234c4ebf9abd34358c6e56532.tar.gz lwn-99387b016022c29234c4ebf9abd34358c6e56532.zip | |
ACPI: processor: perflib: Avoid updating frequency QoS unnecessarily
Modify acpi_processor_get_platform_limit() to avoid updating its
frequency QoS request when the _PPC return value has not changed
by comparing that value to the previous _PPC return value stored in
the performance_platform_limit field of the struct acpi_processor
corresponding to the given CPU.
While at it, do the _PPC return value check against the state count
earlier, to avoid setting performance_platform_limit to an invalid
value, and make acpi_processor_ppc_init() use FREQ_QOS_MAX_DEFAULT_VALUE
as the "no limit" frequency QoS for consistency.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/processor_perflib.c')
| -rw-r--r-- | drivers/acpi/processor_perflib.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c index 0da85fc2a7e4..4265814c74f8 100644 --- a/drivers/acpi/processor_perflib.c +++ b/drivers/acpi/processor_perflib.c @@ -76,13 +76,16 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr) index = ppc; + if (pr->performance_platform_limit == index || + ppc >= pr->performance->state_count) + return 0; + pr_debug("CPU %d: _PPC is %d - frequency %s limited\n", pr->id, index, index ? "is" : "is not"); pr->performance_platform_limit = index; - if (ppc >= pr->performance->state_count || - unlikely(!freq_qos_request_active(&pr->perflib_req))) + if (unlikely(!freq_qos_request_active(&pr->perflib_req))) return 0; /* @@ -178,9 +181,16 @@ void acpi_processor_ppc_init(struct cpufreq_policy *policy) if (!pr) continue; + /* + * Reset performance_platform_limit in case there is a stale + * value in it, so as to make it match the "no limit" QoS value + * below. + */ + pr->performance_platform_limit = 0; + ret = freq_qos_add_request(&policy->constraints, - &pr->perflib_req, - FREQ_QOS_MAX, INT_MAX); + &pr->perflib_req, FREQ_QOS_MAX, + FREQ_QOS_MAX_DEFAULT_VALUE); if (ret < 0) pr_err("Failed to add freq constraint for CPU%d (%d)\n", cpu, ret); |