perfMemory.cpp revision 9099:115188e14c15 
1/*
2 * Copyright (c) 2001, 2015, 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
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7 * published by the Free Software Foundation.
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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
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25#include "precompiled.hpp"
26#include "memory/allocation.inline.hpp"
27#include "runtime/arguments.hpp"
28#include "runtime/java.hpp"
29#include "runtime/mutex.hpp"
30#include "runtime/mutexLocker.hpp"
31#include "runtime/orderAccess.inline.hpp"
32#include "runtime/os.hpp"
33#include "runtime/perfData.hpp"
34#include "runtime/perfMemory.hpp"
35#include "runtime/safepoint.hpp"
36#include "runtime/statSampler.hpp"
37#include "utilities/globalDefinitions.hpp"
38
39// Prefix of performance data file.
40const char               PERFDATA_NAME[] = "hsperfdata";
41
42// Add 1 for the '_' character between PERFDATA_NAME and pid. The '\0' terminating
43// character will be included in the sizeof(PERFDATA_NAME) operation.
44static const size_t PERFDATA_FILENAME_LEN = sizeof(PERFDATA_NAME) +
45                                            UINT_CHARS + 1;
46
47char*                    PerfMemory::_start = NULL;
48char*                    PerfMemory::_end = NULL;
49char*                    PerfMemory::_top = NULL;
50size_t                   PerfMemory::_capacity = 0;
51jint                     PerfMemory::_initialized = false;
52PerfDataPrologue*        PerfMemory::_prologue = NULL;
53
54void perfMemory_init() {
55
56  if (!UsePerfData) return;
57
58  PerfMemory::initialize();
59}
60
61void perfMemory_exit() {
62
63  if (!UsePerfData) return;
64  if (!PerfMemory::is_initialized()) return;
65
66  // Only destroy PerfData objects if we're at a safepoint and the
67  // StatSampler is not active. Otherwise, we risk removing PerfData
68  // objects that are currently being used by running JavaThreads
69  // or the StatSampler. This method is invoked while we are not at
70  // a safepoint during a VM abort so leaving the PerfData objects
71  // around may also help diagnose the failure. In rare cases,
72  // PerfData objects are used in parallel with a safepoint. See
73  // the work around in PerfDataManager::destroy().
74  //
75  if (SafepointSynchronize::is_at_safepoint() && !StatSampler::is_active()) {
76    PerfDataManager::destroy();
77  }
78
79  // Remove the persistent external resources, if any. This method
80  // does not unmap or invalidate any virtual memory allocated during
81  // initialization.
82  //
83  PerfMemory::destroy();
84}
85
86void PerfMemory::initialize() {
87
88  if (_prologue != NULL)
89    // initialization already performed
90    return;
91
92  size_t capacity = align_size_up(PerfDataMemorySize,
93                                  os::vm_allocation_granularity());
94
95  if (PerfTraceMemOps) {
96    tty->print("PerfDataMemorySize = " SIZE_FORMAT ","
97               " os::vm_allocation_granularity = %d,"
98               " adjusted size = " SIZE_FORMAT "\n",
99               PerfDataMemorySize,
100               os::vm_allocation_granularity(),
101               capacity);
102  }
103
104  // allocate PerfData memory region
105  create_memory_region(capacity);
106
107  if (_start == NULL) {
108
109    // the PerfMemory region could not be created as desired. Rather
110    // than terminating the JVM, we revert to creating the instrumentation
111    // on the C heap. When running in this mode, external monitoring
112    // clients cannot attach to and monitor this JVM.
113    //
114    // the warning is issued only in debug mode in order to avoid
115    // additional output to the stdout or stderr output streams.
116    //
117    if (PrintMiscellaneous && Verbose) {
118      warning("Could not create PerfData Memory region, reverting to malloc");
119    }
120
121    _prologue = NEW_C_HEAP_OBJ(PerfDataPrologue, mtInternal);
122  }
123  else {
124
125    // the PerfMemory region was created as expected.
126
127    if (PerfTraceMemOps) {
128      tty->print("PerfMemory created: address = " INTPTR_FORMAT ","
129                 " size = " SIZE_FORMAT "\n",
130                 p2i(_start),
131                 _capacity);
132    }
133
134    _prologue = (PerfDataPrologue *)_start;
135    _end = _start + _capacity;
136    _top = _start + sizeof(PerfDataPrologue);
137  }
138
139  assert(_prologue != NULL, "prologue pointer must be initialized");
140
141#ifdef VM_LITTLE_ENDIAN
142  _prologue->magic = (jint)0xc0c0feca;
143  _prologue->byte_order = PERFDATA_LITTLE_ENDIAN;
144#else
145  _prologue->magic = (jint)0xcafec0c0;
146  _prologue->byte_order = PERFDATA_BIG_ENDIAN;
147#endif
148
149  _prologue->major_version = PERFDATA_MAJOR_VERSION;
150  _prologue->minor_version = PERFDATA_MINOR_VERSION;
151  _prologue->accessible = 0;
152
153  _prologue->entry_offset = sizeof(PerfDataPrologue);
154  _prologue->num_entries = 0;
155  _prologue->used = 0;
156  _prologue->overflow = 0;
157  _prologue->mod_time_stamp = 0;
158
159  OrderAccess::release_store(&_initialized, 1);
160}
161
162void PerfMemory::destroy() {
163
164  if (_prologue == NULL) return;
165
166  if (_start != NULL && _prologue->overflow != 0) {
167
168    // This state indicates that the contiguous memory region exists and
169    // that it wasn't large enough to hold all the counters. In this case,
170    // we output a warning message to the user on exit if the -XX:+Verbose
171    // flag is set (a debug only flag). External monitoring tools can detect
172    // this condition by monitoring the _prologue->overflow word.
173    //
174    // There are two tunables that can help resolve this issue:
175    //   - increase the size of the PerfMemory with -XX:PerfDataMemorySize=<n>
176    //   - decrease the maximum string constant length with
177    //     -XX:PerfMaxStringConstLength=<n>
178    //
179    if (PrintMiscellaneous && Verbose) {
180      warning("PerfMemory Overflow Occurred.\n"
181              "\tCapacity = " SIZE_FORMAT " bytes"
182              "  Used = " SIZE_FORMAT " bytes"
183              "  Overflow = " INT32_FORMAT " bytes"
184              "\n\tUse -XX:PerfDataMemorySize=<size> to specify larger size.",
185              PerfMemory::capacity(),
186              PerfMemory::used(),
187              _prologue->overflow);
188    }
189  }
190
191  if (_start != NULL) {
192
193    // this state indicates that the contiguous memory region was successfully
194    // and that persistent resources may need to be cleaned up. This is
195    // expected to be the typical condition.
196    //
197    delete_memory_region();
198  }
199
200  _start = NULL;
201  _end = NULL;
202  _top = NULL;
203  _prologue = NULL;
204  _capacity = 0;
205}
206
207// allocate an aligned block of memory from the PerfData memory
208// region. This method assumes that the PerfData memory region
209// was aligned on a double word boundary when created.
210//
211char* PerfMemory::alloc(size_t size) {
212
213  if (!UsePerfData) return NULL;
214
215  MutexLocker ml(PerfDataMemAlloc_lock);
216
217  assert(_prologue != NULL, "called before initialization");
218
219  // check that there is enough memory for this request
220  if ((_top + size) >= _end) {
221
222    _prologue->overflow += (jint)size;
223
224    return NULL;
225  }
226
227  char* result = _top;
228
229  _top += size;
230
231  assert(contains(result), "PerfData memory pointer out of range");
232
233  _prologue->used = (jint)used();
234  _prologue->num_entries = _prologue->num_entries + 1;
235
236  return result;
237}
238
239void PerfMemory::mark_updated() {
240  if (!UsePerfData) return;
241
242  _prologue->mod_time_stamp = os::elapsed_counter();
243}
244
245// Returns the complete path including the file name of performance data file.
246// Caller is expected to release the allocated memory.
247char* PerfMemory::get_perfdata_file_path() {
248  char* dest_file = NULL;
249
250  if (PerfDataSaveFile != NULL) {
251    // dest_file_name stores the validated file name if file_name
252    // contains %p which will be replaced by pid.
253    dest_file = NEW_C_HEAP_ARRAY(char, JVM_MAXPATHLEN, mtInternal);
254    if(!Arguments::copy_expand_pid(PerfDataSaveFile, strlen(PerfDataSaveFile),
255                                   dest_file, JVM_MAXPATHLEN)) {
256      FREE_C_HEAP_ARRAY(char, dest_file);
257      if (PrintMiscellaneous && Verbose) {
258        warning("Invalid performance data file path name specified, "\
259                "fall back to a default name");
260      }
261    } else {
262      return dest_file;
263    }
264  }
265  // create the name of the file for retaining the instrumentation memory.
266  dest_file = NEW_C_HEAP_ARRAY(char, PERFDATA_FILENAME_LEN, mtInternal);
267  jio_snprintf(dest_file, PERFDATA_FILENAME_LEN,
268               "%s_%d", PERFDATA_NAME, os::current_process_id());
269
270  return dest_file;
271}
272