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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2014 UnitedStack <haomai@unitedstack.com>
*
* Author: Haomai Wang <haomaiwang@gmail.com>
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
/* Copyright (c) 2011-2014 Stanford University
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR(S) DISCLAIM ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL AUTHORS BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef CEPH_CYCLES_H
#define CEPH_CYCLES_H
#include <cstdint>
/**
* This class provides static methods that read the fine-grain CPU
* cycle counter and translate between cycle-level times and absolute
* times.
*/
class Cycles {
public:
static void init();
/**
* Return the current value of the fine-grain CPU cycle counter
* (accessed via the RDTSC instruction).
*/
static __inline __attribute__((always_inline)) uint64_t rdtsc() {
#if defined(__i386__)
int64_t ret;
__asm__ volatile ("rdtsc" : "=A" (ret) );
return ret;
#elif defined(__x86_64__) || defined(__amd64__)
uint32_t lo, hi;
__asm__ __volatile__("rdtsc" : "=a" (lo), "=d" (hi));
return (((uint64_t)hi << 32) | lo);
#elif defined(__aarch64__)
//
// arch/arm64/include/asm/arch_timer.h
//
// static inline u64 arch_counter_get_cntvct(void)
// {
// u64 cval;
//
// isb();
// asm volatile("mrs %0, cntvct_el0" : "=r" (cval));
//
// return cval;
// }
//
// https://github.com/cloudius-systems/osv/blob/master/arch/aarch64/arm-clock.cc
uint64_t cntvct;
asm volatile ("isb; mrs %0, cntvct_el0; isb; " : "=r" (cntvct) :: "memory");
return cntvct;
#elif defined(__powerpc__) || defined (__powerpc64__)
// Based on:
// https://github.com/randombit/botan/blob/net.randombit.botan/src/lib/entropy/hres_timer/hres_timer.cpp
uint32_t lo = 0, hi = 0;
asm volatile("mftbu %0; mftb %1" : "=r" (hi), "=r" (lo));
return (((uint64_t)hi << 32) | lo);
#elif defined(__s390__)
uint64_t tsc;
asm volatile("stck %0" : "=Q" (tsc) : : "cc");
return tsc;
#else
#warning No high-precision counter available for your OS/arch
return 0;
#endif
}
static double per_second();
static double to_seconds(uint64_t cycles, double cycles_per_sec = 0);
static uint64_t from_seconds(double seconds, double cycles_per_sec = 0);
static uint64_t to_microseconds(uint64_t cycles, double cycles_per_sec = 0);
static uint64_t to_nanoseconds(uint64_t cycles, double cycles_per_sec = 0);
static uint64_t from_nanoseconds(uint64_t ns, double cycles_per_sec = 0);
static void sleep(uint64_t us);
private:
Cycles();
/// Conversion factor between cycles and the seconds; computed by
/// Cycles::init.
static double cycles_per_sec;
/**
* Returns the conversion factor between cycles in seconds, using
* a mock value for testing when appropriate.
*/
static __inline __attribute__((always_inline)) double get_cycles_per_sec() {
return cycles_per_sec;
}
};
#endif // CEPH_CYCLES_H
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