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https://git.rwth-aachen.de/acs/public/villas/node/
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48 lines
1.2 KiB
C++
48 lines
1.2 KiB
C++
/* Measure time and sleep with IA-32 time-stamp counter.
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*
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* Author: Steffen Vogel <post@steffenvogel.de>
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* SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <villas/tsc.hpp>
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using namespace villas;
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int tsc_init(struct Tsc *t) {
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uint32_t eax = 0, ebx = 0, ecx = 0, edx = 0;
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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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__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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#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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return t->frequency / rate;
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}
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