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