diff options
| author | Viresh Kumar <viresh.kumar@linaro.org> | 2019-04-29 15:03:58 +0530 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-05-10 12:20:36 +0200 |
| commit | df24014abe3694e7c34ce5e50248611b7a93fe83 (patch) | |
| tree | 98d5dc569e611f1cffec3a5c7bfeb66097c01283 /arch/x86 | |
| parent | 8f5e823f9131a430b12f73e9436d7486e20c16f5 (diff) | |
| download | linux-df24014abe3694e7c34ce5e50248611b7a93fe83.tar.bz2 | |
cpufreq: Call transition notifier only once for each policy
Currently, the notifiers are called once for each CPU of the policy->cpus
cpumask. It would be more optimal if the notifier can be called only
once and all the relevant information be provided to it. Out of the 23
drivers that register for the transition notifiers today, only 4 of them
do per-cpu updates and the callback for the rest can be called only once
for the policy without any impact.
This would also avoid multiple function calls to the notifier callbacks
and reduce multiple iterations of notifier core's code (which does
locking as well).
This patch adds pointer to the cpufreq policy to the struct
cpufreq_freqs, so the notifier callback has all the information
available to it with a single call. The five drivers which perform
per-cpu updates are updated to use the cpufreq policy. The freqs->cpu
field is redundant now and is removed.
Acked-by: David S. Miller <davem@davemloft.net> (sparc)
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/tsc.c | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 31 |
2 files changed, 21 insertions, 12 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 15b5e98a86f9..356dfc555a27 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -979,7 +979,7 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, if (!(freq->flags & CPUFREQ_CONST_LOOPS)) mark_tsc_unstable("cpufreq changes"); - set_cyc2ns_scale(tsc_khz, freq->cpu, rdtsc()); + set_cyc2ns_scale(tsc_khz, freq->policy->cpu, rdtsc()); } return 0; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b5edc8e3ce1d..22cc90baa67f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6698,10 +6698,8 @@ static void kvm_hyperv_tsc_notifier(void) } #endif -static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long val, - void *data) +static void __kvmclock_cpufreq_notifier(struct cpufreq_freqs *freq, int cpu) { - struct cpufreq_freqs *freq = data; struct kvm *kvm; struct kvm_vcpu *vcpu; int i, send_ipi = 0; @@ -6745,17 +6743,12 @@ static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long va * */ - if (val == CPUFREQ_PRECHANGE && freq->old > freq->new) - return 0; - if (val == CPUFREQ_POSTCHANGE && freq->old < freq->new) - return 0; - - smp_call_function_single(freq->cpu, tsc_khz_changed, freq, 1); + smp_call_function_single(cpu, tsc_khz_changed, freq, 1); spin_lock(&kvm_lock); list_for_each_entry(kvm, &vm_list, vm_list) { kvm_for_each_vcpu(i, vcpu, kvm) { - if (vcpu->cpu != freq->cpu) + if (vcpu->cpu != cpu) continue; kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); if (vcpu->cpu != smp_processor_id()) @@ -6777,8 +6770,24 @@ static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long va * guest context is entered kvmclock will be updated, * so the guest will not see stale values. */ - smp_call_function_single(freq->cpu, tsc_khz_changed, freq, 1); + smp_call_function_single(cpu, tsc_khz_changed, freq, 1); } +} + +static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long val, + void *data) +{ + struct cpufreq_freqs *freq = data; + int cpu; + + if (val == CPUFREQ_PRECHANGE && freq->old > freq->new) + return 0; + if (val == CPUFREQ_POSTCHANGE && freq->old < freq->new) + return 0; + + for_each_cpu(cpu, freq->policy->cpus) + __kvmclock_cpufreq_notifier(freq, cpu); + return 0; } |