1 /* 2 * Copyright (c) 2014, 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. 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 SHARE_RUNTIME_RTMLOCKING_HPP 26 #define SHARE_RUNTIME_RTMLOCKING_HPP 27 28 // Generate RTM (Restricted Transactional Memory) locking code for all inflated 29 // locks when "UseRTMLocking" option is on with normal locking mechanism as fall back 30 // handler. 31 // 32 // On abort/lock busy the lock will be retried a fixed number of times under RTM 33 // as specified by "RTMRetryCount" option. The locks which abort too often 34 // can be auto tuned or manually tuned. 35 // 36 // Auto-tuning can be done on an option like UseRTMDeopt and it will need abort 37 // ratio calculation for each lock. The abort ratio will be calculated after 38 // "RTMAbortThreshold" number of aborts is reached. The formulas are: 39 // 40 // Aborted transactions = abort_count * 100 41 // All transactions = total_count * RTMTotalCountIncrRate 42 // 43 // Aborted transactions >= All transactions * RTMAbortRatio 44 // 45 // If "UseRTMDeopt" is on and the aborts ratio reaches "RTMAbortRatio" 46 // the method containing the lock will be deoptimized and recompiled with 47 // all locks as normal locks. If the abort ratio continues to remain low after 48 // "RTMLockingThreshold" locks are attempted, then the method will be deoptimized 49 // and recompiled with all locks as RTM locks without abort ratio calculation code. 50 // The abort ratio calculation can be delayed by specifying flag 51 // -XX:RTMLockingCalculationDelay in millisecond. 52 // 53 // For manual tuning the abort statistics for each lock needs to be provided 54 // to the user on some JVM option like "PrintPreciseRTMLockingStatistics". 55 // Based on the abort statistics users can create a .hotspot_compiler file 56 // or use -XX:CompileCommand=option,class::method,NoRTMLockEliding 57 // to specify for which methods to disable RTM locking. 58 // 59 // When UseRTMForStackLocks option is enabled along with UseRTMLocking option, 60 // the RTM locking code is generated for stack locks too. 61 // The retries, auto-tuning support and rtm locking statistics are all 62 // supported for stack locks just like inflated locks. 63 64 // RTM locking counters 65 class RTMLockingCounters { 66 private: 67 uintx _total_count; // Total RTM locks count 68 uintx _abort_count; // Total aborts count 69 70 public: 71 enum { ABORT_STATUS_LIMIT = 6 }; 72 // Counters per RTM Abort Status. Incremented with +PrintPreciseRTMLockingStatistics 73 // RTM uses the EAX register to communicate abort status to software. 74 // Following an RTM abort the EAX register has the following definition. 75 // 76 // EAX register bit position Meaning 77 // 0 Set if abort caused by XABORT instruction. 78 // 1 If set, the transaction may succeed on a retry. This bit is always clear if bit 0 is set. 79 // 2 Set if another logical processor conflicted with a memory address that was part of the transaction that aborted. 80 // 3 Set if an internal buffer overflowed. 81 // 4 Set if a debug breakpoint was hit. 82 // 5 Set if an abort occurred during execution of a nested transaction. 83 private: 84 uintx _abortX_count[ABORT_STATUS_LIMIT]; 85 static const char* _abortX_desc[ABORT_STATUS_LIMIT]; 86 87 public: 88 static uintx _calculation_flag; rtm_calculation_flag_addr()89 static uintx* rtm_calculation_flag_addr() { return &_calculation_flag; } 90 91 static void init(); 92 RTMLockingCounters()93 RTMLockingCounters() : _total_count(0), _abort_count(0) { 94 for (int i = 0; i < ABORT_STATUS_LIMIT; i++) { 95 _abortX_count[i] = 0; 96 } 97 } 98 total_count_addr()99 uintx* total_count_addr() { return &_total_count; } abort_count_addr()100 uintx* abort_count_addr() { return &_abort_count; } abortX_count_addr()101 uintx* abortX_count_addr() { return &_abortX_count[0]; } 102 total_count_offset()103 static int total_count_offset() { return (int)offset_of(RTMLockingCounters, _total_count); } abort_count_offset()104 static int abort_count_offset() { return (int)offset_of(RTMLockingCounters, _abort_count); } abortX_count_offset()105 static int abortX_count_offset() { return (int)offset_of(RTMLockingCounters, _abortX_count[0]); } 106 107 nonzero()108 bool nonzero() { return (_abort_count + _total_count) > 0; } 109 110 void print_on(outputStream* st) const; 111 void print() const; 112 }; 113 114 #endif // SHARE_RUNTIME_RTMLOCKING_HPP 115