| /* |
| * Copyright (c) 2014, 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 SHARE_VM_RUNTIME_RTMLOCKING_HPP |
| #define SHARE_VM_RUNTIME_RTMLOCKING_HPP |
| |
| // Generate RTM (Restricted Transactional Memory) locking code for all inflated |
| // locks when "UseRTMLocking" option is on with normal locking mechanism as fall back |
| // handler. |
| // |
| // On abort/lock busy the lock will be retried a fixed number of times under RTM |
| // as specified by "RTMRetryCount" option. The locks which abort too often |
| // can be auto tuned or manually tuned. |
| // |
| // Auto-tuning can be done on an option like UseRTMDeopt and it will need abort |
| // ratio calculation for each lock. The abort ratio will be calculated after |
| // "RTMAbortThreshold" number of aborts is reached. The formulas are: |
| // |
| // Aborted transactions = abort_count * 100 |
| // All transactions = total_count * RTMTotalCountIncrRate |
| // |
| // Aborted transactions >= All transactions * RTMAbortRatio |
| // |
| // If "UseRTMDeopt" is on and the aborts ratio reaches "RTMAbortRatio" |
| // the method containing the lock will be deoptimized and recompiled with |
| // all locks as normal locks. If the abort ratio continues to remain low after |
| // "RTMLockingThreshold" locks are attempted, then the method will be deoptimized |
| // and recompiled with all locks as RTM locks without abort ratio calculation code. |
| // The abort ratio calculation can be delayed by specifying flag |
| // -XX:RTMLockingCalculationDelay in millisecond. |
| // |
| // For manual tuning the abort statistics for each lock needs to be provided |
| // to the user on some JVM option like "PrintPreciseRTMLockingStatistics". |
| // Based on the abort statistics users can create a .hotspot_compiler file |
| // or use -XX:CompileCommand=option,class::method,NoRTMLockEliding |
| // to specify for which methods to disable RTM locking. |
| // |
| // When UseRTMForStackLocks option is enabled along with UseRTMLocking option, |
| // the RTM locking code is generated for stack locks too. |
| // The retries, auto-tuning support and rtm locking statistics are all |
| // supported for stack locks just like inflated locks. |
| |
| // RTM locking counters |
| class RTMLockingCounters VALUE_OBJ_CLASS_SPEC { |
| private: |
| uintx _total_count; // Total RTM locks count |
| uintx _abort_count; // Total aborts count |
| |
| public: |
| enum { ABORT_STATUS_LIMIT = 6 }; |
| // Counters per RTM Abort Status. Incremented with +PrintPreciseRTMLockingStatistics |
| // RTM uses the EAX register to communicate abort status to software. |
| // Following an RTM abort the EAX register has the following definition. |
| // |
| // EAX register bit position Meaning |
| // 0 Set if abort caused by XABORT instruction. |
| // 1 If set, the transaction may succeed on a retry. This bit is always clear if bit 0 is set. |
| // 2 Set if another logical processor conflicted with a memory address that was part of the transaction that aborted. |
| // 3 Set if an internal buffer overflowed. |
| // 4 Set if a debug breakpoint was hit. |
| // 5 Set if an abort occurred during execution of a nested transaction. |
| private: |
| uintx _abortX_count[ABORT_STATUS_LIMIT]; |
| |
| public: |
| static uintx _calculation_flag; |
| static uintx* rtm_calculation_flag_addr() { return &_calculation_flag; } |
| |
| static void init(); |
| |
| RTMLockingCounters() : _total_count(0), _abort_count(0) { |
| for (int i = 0; i < ABORT_STATUS_LIMIT; i++) { |
| _abortX_count[i] = 0; |
| } |
| } |
| |
| uintx* total_count_addr() { return &_total_count; } |
| uintx* abort_count_addr() { return &_abort_count; } |
| uintx* abortX_count_addr() { return &_abortX_count[0]; } |
| |
| static int total_count_offset() { return (int)offset_of(RTMLockingCounters, _total_count); } |
| static int abort_count_offset() { return (int)offset_of(RTMLockingCounters, _abort_count); } |
| static int abortX_count_offset() { return (int)offset_of(RTMLockingCounters, _abortX_count[0]); } |
| |
| |
| bool nonzero() { return (_abort_count + _total_count) > 0; } |
| |
| void print_on(outputStream* st); |
| void print() { print_on(tty); } |
| }; |
| |
| #endif // SHARE_VM_RUNTIME_RTMLOCKING_HPP |