1 /* 2 * Copyright (c) 2012, 2018, 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. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef CPU_X86_VM_RDTSC_X86_HPP 26 #define CPU_X86_VM_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 39 class 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 elapsed_counter_baseline(); 47 static bool initialize(); 48 }; 49 50 #endif // CPU_X86_VM_RDTSC_X86_HPP