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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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x86: merge the TSC cpu-freq code
Unify the TSC cpufreq code. Signed-off-by: Alok N Kataria <akataria@vmware.com> Signed-off-by: Dan Hecht <dhecht@vmware.com> Cc: Dan Hecht <dhecht@vmware.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Alok Kataria
Ingo Molnar
parent
bfc0f5947a
commit
2dbe06faf3
@ -4,6 +4,7 @@
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#include <linux/module.h>
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#include <linux/timer.h>
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#include <linux/acpi_pmtmr.h>
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#include <linux/cpufreq.h>
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#include <asm/hpet.h>
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@ -215,3 +216,116 @@ int recalibrate_cpu_khz(void)
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EXPORT_SYMBOL(recalibrate_cpu_khz);
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#endif /* CONFIG_X86_32 */
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/* Accelerators for sched_clock()
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* convert from cycles(64bits) => nanoseconds (64bits)
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* basic equation:
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* ns = cycles / (freq / ns_per_sec)
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* ns = cycles * (ns_per_sec / freq)
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* ns = cycles * (10^9 / (cpu_khz * 10^3))
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* ns = cycles * (10^6 / cpu_khz)
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*
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* Then we use scaling math (suggested by george@mvista.com) to get:
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* ns = cycles * (10^6 * SC / cpu_khz) / SC
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* ns = cycles * cyc2ns_scale / SC
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*
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* And since SC is a constant power of two, we can convert the div
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* into a shift.
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*
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* We can use khz divisor instead of mhz to keep a better precision, since
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* cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
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* (mathieu.desnoyers@polymtl.ca)
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*
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* -johnstul@us.ibm.com "math is hard, lets go shopping!"
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*/
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DEFINE_PER_CPU(unsigned long, cyc2ns);
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void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
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{
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unsigned long long tsc_now, ns_now;
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unsigned long flags, *scale;
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local_irq_save(flags);
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sched_clock_idle_sleep_event();
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scale = &per_cpu(cyc2ns, cpu);
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rdtscll(tsc_now);
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ns_now = __cycles_2_ns(tsc_now);
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if (cpu_khz)
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*scale = (NSEC_PER_MSEC << CYC2NS_SCALE_FACTOR)/cpu_khz;
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sched_clock_idle_wakeup_event(0);
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local_irq_restore(flags);
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}
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#ifdef CONFIG_CPU_FREQ
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/* Frequency scaling support. Adjust the TSC based timer when the cpu frequency
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* changes.
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*
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* RED-PEN: On SMP we assume all CPUs run with the same frequency. It's
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* not that important because current Opteron setups do not support
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* scaling on SMP anyroads.
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*
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* Should fix up last_tsc too. Currently gettimeofday in the
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* first tick after the change will be slightly wrong.
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*/
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static unsigned int ref_freq;
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static unsigned long loops_per_jiffy_ref;
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static unsigned long tsc_khz_ref;
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static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
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void *data)
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{
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struct cpufreq_freqs *freq = data;
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unsigned long *lpj, dummy;
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if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC))
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return 0;
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lpj = &dummy;
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if (!(freq->flags & CPUFREQ_CONST_LOOPS))
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#ifdef CONFIG_SMP
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lpj = &cpu_data(freq->cpu).loops_per_jiffy;
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#else
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lpj = &boot_cpu_data.loops_per_jiffy;
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#endif
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if (!ref_freq) {
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ref_freq = freq->old;
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loops_per_jiffy_ref = *lpj;
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tsc_khz_ref = tsc_khz;
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}
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if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
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(val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
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(val == CPUFREQ_RESUMECHANGE)) {
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*lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
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tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
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if (!(freq->flags & CPUFREQ_CONST_LOOPS))
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mark_tsc_unstable("cpufreq changes");
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}
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set_cyc2ns_scale(tsc_khz_ref, freq->cpu);
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return 0;
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}
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static struct notifier_block time_cpufreq_notifier_block = {
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.notifier_call = time_cpufreq_notifier
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};
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static int __init cpufreq_tsc(void)
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{
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cpufreq_register_notifier(&time_cpufreq_notifier_block,
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CPUFREQ_TRANSITION_NOTIFIER);
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return 0;
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}
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core_initcall(cpufreq_tsc);
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#endif /* CONFIG_CPU_FREQ */
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@ -18,119 +18,6 @@
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extern int tsc_unstable;
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extern int tsc_disabled;
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/* Accelerators for sched_clock()
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* convert from cycles(64bits) => nanoseconds (64bits)
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* basic equation:
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* ns = cycles / (freq / ns_per_sec)
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* ns = cycles * (ns_per_sec / freq)
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* ns = cycles * (10^9 / (cpu_khz * 10^3))
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* ns = cycles * (10^6 / cpu_khz)
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*
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* Then we use scaling math (suggested by george@mvista.com) to get:
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* ns = cycles * (10^6 * SC / cpu_khz) / SC
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* ns = cycles * cyc2ns_scale / SC
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*
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* And since SC is a constant power of two, we can convert the div
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* into a shift.
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*
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* We can use khz divisor instead of mhz to keep a better precision, since
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* cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
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* (mathieu.desnoyers@polymtl.ca)
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*
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* -johnstul@us.ibm.com "math is hard, lets go shopping!"
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*/
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DEFINE_PER_CPU(unsigned long, cyc2ns);
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void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
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{
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unsigned long long tsc_now, ns_now;
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unsigned long flags, *scale;
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local_irq_save(flags);
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sched_clock_idle_sleep_event();
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scale = &per_cpu(cyc2ns, cpu);
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rdtscll(tsc_now);
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ns_now = __cycles_2_ns(tsc_now);
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if (cpu_khz)
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*scale = (NSEC_PER_MSEC << CYC2NS_SCALE_FACTOR)/cpu_khz;
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/*
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* Start smoothly with the new frequency:
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*/
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sched_clock_idle_wakeup_event(0);
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local_irq_restore(flags);
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}
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#ifdef CONFIG_CPU_FREQ
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/*
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* if the CPU frequency is scaled, TSC-based delays will need a different
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* loops_per_jiffy value to function properly.
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*/
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static unsigned int ref_freq;
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static unsigned long loops_per_jiffy_ref;
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static unsigned long cpu_khz_ref;
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static int
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time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data)
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{
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struct cpufreq_freqs *freq = data;
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if (!ref_freq) {
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if (!freq->old){
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ref_freq = freq->new;
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return 0;
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}
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ref_freq = freq->old;
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loops_per_jiffy_ref = cpu_data(freq->cpu).loops_per_jiffy;
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cpu_khz_ref = cpu_khz;
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}
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if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
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(val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
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(val == CPUFREQ_RESUMECHANGE)) {
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if (!(freq->flags & CPUFREQ_CONST_LOOPS))
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cpu_data(freq->cpu).loops_per_jiffy =
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cpufreq_scale(loops_per_jiffy_ref,
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ref_freq, freq->new);
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if (cpu_khz) {
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if (num_online_cpus() == 1)
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cpu_khz = cpufreq_scale(cpu_khz_ref,
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ref_freq, freq->new);
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if (!(freq->flags & CPUFREQ_CONST_LOOPS)) {
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tsc_khz = cpu_khz;
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set_cyc2ns_scale(cpu_khz, freq->cpu);
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/*
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* TSC based sched_clock turns
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* to junk w/ cpufreq
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*/
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mark_tsc_unstable("cpufreq changes");
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}
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}
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}
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return 0;
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}
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static struct notifier_block time_cpufreq_notifier_block = {
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.notifier_call = time_cpufreq_notifier
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};
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static int __init cpufreq_tsc(void)
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{
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return cpufreq_register_notifier(&time_cpufreq_notifier_block,
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CPUFREQ_TRANSITION_NOTIFIER);
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}
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core_initcall(cpufreq_tsc);
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#endif
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/* clock source code */
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static struct clocksource clocksource_tsc;
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@ -16,120 +16,6 @@
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extern int tsc_unstable;
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extern int tsc_disabled;
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/* Accelerators for sched_clock()
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* convert from cycles(64bits) => nanoseconds (64bits)
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* basic equation:
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* ns = cycles / (freq / ns_per_sec)
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* ns = cycles * (ns_per_sec / freq)
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* ns = cycles * (10^9 / (cpu_khz * 10^3))
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* ns = cycles * (10^6 / cpu_khz)
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*
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* Then we use scaling math (suggested by george@mvista.com) to get:
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* ns = cycles * (10^6 * SC / cpu_khz) / SC
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* ns = cycles * cyc2ns_scale / SC
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*
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* And since SC is a constant power of two, we can convert the div
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* into a shift.
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*
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* We can use khz divisor instead of mhz to keep a better precision, since
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* cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
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* (mathieu.desnoyers@polymtl.ca)
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*
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* -johnstul@us.ibm.com "math is hard, lets go shopping!"
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*/
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DEFINE_PER_CPU(unsigned long, cyc2ns);
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void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
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{
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unsigned long long tsc_now, ns_now;
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unsigned long flags, *scale;
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local_irq_save(flags);
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sched_clock_idle_sleep_event();
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scale = &per_cpu(cyc2ns, cpu);
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rdtscll(tsc_now);
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ns_now = __cycles_2_ns(tsc_now);
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if (cpu_khz)
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*scale = (NSEC_PER_MSEC << CYC2NS_SCALE_FACTOR)/cpu_khz;
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sched_clock_idle_wakeup_event(0);
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local_irq_restore(flags);
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}
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#ifdef CONFIG_CPU_FREQ
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/* Frequency scaling support. Adjust the TSC based timer when the cpu frequency
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* changes.
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*
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* RED-PEN: On SMP we assume all CPUs run with the same frequency. It's
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* not that important because current Opteron setups do not support
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* scaling on SMP anyroads.
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*
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* Should fix up last_tsc too. Currently gettimeofday in the
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* first tick after the change will be slightly wrong.
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*/
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static unsigned int ref_freq;
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static unsigned long loops_per_jiffy_ref;
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static unsigned long tsc_khz_ref;
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static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
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void *data)
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{
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struct cpufreq_freqs *freq = data;
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unsigned long *lpj, dummy;
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if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC))
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return 0;
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lpj = &dummy;
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if (!(freq->flags & CPUFREQ_CONST_LOOPS))
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#ifdef CONFIG_SMP
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lpj = &cpu_data(freq->cpu).loops_per_jiffy;
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#else
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lpj = &boot_cpu_data.loops_per_jiffy;
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#endif
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if (!ref_freq) {
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ref_freq = freq->old;
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loops_per_jiffy_ref = *lpj;
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tsc_khz_ref = tsc_khz;
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}
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if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
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(val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
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(val == CPUFREQ_RESUMECHANGE)) {
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*lpj =
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cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
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tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
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if (!(freq->flags & CPUFREQ_CONST_LOOPS))
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mark_tsc_unstable("cpufreq changes");
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}
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set_cyc2ns_scale(tsc_khz_ref, freq->cpu);
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return 0;
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}
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static struct notifier_block time_cpufreq_notifier_block = {
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.notifier_call = time_cpufreq_notifier
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};
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static int __init cpufreq_tsc(void)
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{
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cpufreq_register_notifier(&time_cpufreq_notifier_block,
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CPUFREQ_TRANSITION_NOTIFIER);
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return 0;
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}
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core_initcall(cpufreq_tsc);
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#endif
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/*
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* Make an educated guess if the TSC is trustworthy and synchronized
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* over all CPUs.
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