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54 lines
1.1 KiB
54 lines
1.1 KiB
8 years ago
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// Copyright (c) 2016 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include "perf.h"
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#if defined(__i386__) || defined(__x86_64__)
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/* These architectures support quering the cycle counter
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* from user space, no need for any syscall overhead.
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*/
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void perf_init(void) { }
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void perf_fini(void) { }
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#elif defined(__linux__)
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#include <unistd.h>
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#include <sys/syscall.h>
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#include <linux/perf_event.h>
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static int fd = -1;
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static struct perf_event_attr attr;
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void perf_init(void)
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{
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attr.type = PERF_TYPE_HARDWARE;
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attr.config = PERF_COUNT_HW_CPU_CYCLES;
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fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
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}
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void perf_fini(void)
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{
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if (fd != -1) {
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close(fd);
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}
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}
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uint64_t perf_cpucycles(void)
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{
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uint64_t result = 0;
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if (fd == -1 || read(fd, &result, sizeof(result)) < (ssize_t)sizeof(result)) {
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return 0;
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}
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return result;
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}
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#else /* Unhandled platform */
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void perf_init(void) { }
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void perf_fini(void) { }
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uint64_t perf_cpucycles(void) { return 0; }
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#endif
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