src/hotspot/share/runtime/rtmLocking.hpp
changeset 47216 71c04702a3d5
parent 23491 f690330b10b9
child 49364 601146c66cad
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/runtime/rtmLocking.hpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,113 @@
+/*
+ * 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