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53 lines
1.1 KiB
53 lines
1.1 KiB
// 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 querying 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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