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Diffstat (limited to 'src/common/Cycles.h')
| -rw-r--r-- | src/common/Cycles.h | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/src/common/Cycles.h b/src/common/Cycles.h new file mode 100644 index 000000000..16e0aa67f --- /dev/null +++ b/src/common/Cycles.h @@ -0,0 +1,115 @@ +// -*- 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 + +/** + * 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 |