perf.cpp
No OneTemporary
Actions

Size

1 KB

Subscribers

None

perf.cpp
View Options

	// Copyright (c) 2016 The Bitcoin Core developers
	// Distributed under the MIT software license, see the accompanying
	// file COPYING or http://www.opensource.org/licenses/mit-license.php.

	#include "perf.h"

	#if defined(__i386__) \|\| defined(__x86_64__)

	/* These architectures support querying the cycle counter
	* from user space, no need for any syscall overhead.
	*/
	void perf_init(void) {}
	void perf_fini(void) {}

	#elif defined(__linux__)

	#include <linux/perf_event.h>
	#include <sys/syscall.h>
	#include <unistd.h>

	static int fd = -1;
	static struct perf_event_attr attr;

	void perf_init(void) {
	attr.type = PERF_TYPE_HARDWARE;
	attr.config = PERF_COUNT_HW_CPU_CYCLES;
	fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
	}

	void perf_fini(void) {
	if (fd != -1) {
	close(fd);
	}
	}

	uint64_t perf_cpucycles(void) {
	uint64_t result = 0;
	if (fd == -1 \|\|
	read(fd, &result, sizeof(result)) < (ssize_t)sizeof(result)) {
	return 0;
	}
	return result;
	}

	#else /* Unhandled platform */

	void perf_init(void) {}
	void perf_fini(void) {}
	uint64_t perf_cpucycles(void) {
	return 0;
	}

	#endif