1/*
2 * Copyright (c) 2012, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25#ifndef CPU_X86_RDTSC_X86_HPP
26#define CPU_X86_RDTSC_X86_HPP
27
28#include "memory/allocation.hpp"
29#include "utilities/macros.hpp"
30
31// Interface to the x86 rdtsc() time counter, if available.
32// Not guaranteed to be synchronized across hardware threads and
33// therefore software threads, and can be updated asynchronously
34// by software. elapsed_counter() can jump backwards
35// as well as jump forward when threads query different cores/sockets.
36// Very much not recommended for general use.
37// INVTSC is a minimal requirement for auto-enablement.
38
39class Rdtsc : AllStatic {
40 public:
41 static jlong elapsed_counter(); // provides quick time stamps
42 static jlong frequency(); // tsc register
43 static bool is_supported(); // InvariantTSC
44 static jlong raw(); // direct rdtsc() access
45 static bool is_elapsed_counter_enabled(); // turn off with -XX:-UseFastUnorderedTimeStamps
46 static jlong epoch();
47 static bool initialize();
48};
49
50#endif // CPU_X86_RDTSC_X86_HPP
51