/** Measure time and sleep with IA-32 time-stamp counter. * * @file * @author Steffen Vogel * @copyright 2018, Institute for Automation of Complex Power Systems, EONERC * @license GNU General Public License (version 3) * * VILLASnode * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . *********************************************************************************/ #include int tsc_init(struct tsc *t) { uint32_t eax, ebx, ecx, edx; /** Check if TSC is supported */ __get_cpuid(0x1, &eax, &ebx, &ecx, &edx); if (!(edx & bit_TSC)) return -2; /** Check if RDTSCP instruction is supported */ __get_cpuid(0x80000001, &eax, &ebx, &ecx, &edx); t->rdtscp_supported = edx & bit_RDTSCP; /** Check if TSC is invariant */ __get_cpuid(0x80000007, &eax, &ebx, &ecx, &edx); t->is_invariant = edx & bit_TSC_INVARIANT; /** Intel SDM Vol 3, Section 18.7.3: * Nominal TSC frequency = CPUID.15H.ECX[31:0] * CPUID.15H.EBX[31:0] ) รท CPUID.15H.EAX[31:0] */ __get_cpuid(0x15, &eax, &ebx, &ecx, &edx); if (ecx != 0) t->frequency = ecx * ebx / eax; else { int ret; #ifdef __linux__ ret = kernel_get_cpu_frequency(&t->frequency); if (ret) return ret; #elif defined(__APPLE__) int64_t frequency; size_t lenp = sizeof(frequency); /** @todo: machdep.tsc.frequency seems to be a measured frequency (based on local APIC? * We should figure out which frequency is more accurate */ // ret = sysctlbyname("hw.cpufrequency", &frequency, &lenp, NULL, 0); ret = sysctlbyname("machdep.tsc.frequency", &frequency, &lenp, NULL, 0); if (ret) return ret; t->frequency = frequency; #endif } return 0; } uint64_t tsc_rate_to_cycles(struct tsc *t, double rate) { return t->frequency / rate; }