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/*
* Copyright (c) 2012, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef CPU_X86_RDTSC_X86_HPP
#define CPU_X86_RDTSC_X86_HPP
#include "memory/allStatic.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/macros.hpp"
// Interface to the x86 rdtsc() time counter, if available.
// Not guaranteed to be synchronized across hardware threads and
// therefore software threads, and can be updated asynchronously
// by software. elapsed_counter() can jump backwards
// as well as jump forward when threads query different cores/sockets.
// Very much not recommended for general use.
// INVTSC is a minimal requirement for auto-enablement.
class Rdtsc : AllStatic {
public:
static jlong elapsed_counter(); // provides quick time stamps
static jlong frequency(); // tsc register
static bool is_supported(); // InvariantTSC
static jlong raw(); // direct rdtsc() access
static bool is_elapsed_counter_enabled(); // turn off with -XX:-UseFastUnorderedTimeStamps
static jlong epoch();
static bool initialize();
};
#endif // CPU_X86_RDTSC_X86_HPP
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