1/*
2 * Copyright (c) 2001, 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#include "precompiled.hpp"
26#include "jvm.h"
27#include "logging/log.hpp"
28#include "memory/allocation.inline.hpp"
29#include "runtime/arguments.hpp"
30#include "runtime/java.hpp"
31#include "runtime/mutex.hpp"
32#include "runtime/mutexLocker.hpp"
33#include "runtime/orderAccess.hpp"
34#include "runtime/os.hpp"
35#include "runtime/perfData.hpp"
36#include "runtime/perfMemory.hpp"
37#include "runtime/safepoint.hpp"
38#include "runtime/statSampler.hpp"
39#include "utilities/align.hpp"
40#include "utilities/globalDefinitions.hpp"
41
42// Prefix of performance data file.
43const char PERFDATA_NAME[] = "hsperfdata";
44
45// Add 1 for the '_' character between PERFDATA_NAME and pid. The '\0' terminating
46// character will be included in the sizeof(PERFDATA_NAME) operation.
47static const size_t PERFDATA_FILENAME_LEN = sizeof(PERFDATA_NAME) +
48 UINT_CHARS + 1;
49
50char* PerfMemory::_start = NULL;
51char* PerfMemory::_end = NULL;
52char* PerfMemory::_top = NULL;
53size_t PerfMemory::_capacity = 0;
54int PerfMemory::_initialized = false;
55PerfDataPrologue* PerfMemory::_prologue = NULL;
56bool PerfMemory::_destroyed = false;
57
58void perfMemory_init() {
59
60 if (!UsePerfData) return;
61
62 PerfMemory::initialize();
63}
64
65void perfMemory_exit() {
66
67 if (!UsePerfData) return;
68 if (!PerfMemory::is_usable()) return;
69
70 // Only destroy PerfData objects if we're at a safepoint and the
71 // StatSampler is not active. Otherwise, we risk removing PerfData
72 // objects that are currently being used by running JavaThreads
73 // or the StatSampler. This method is invoked while we are not at
74 // a safepoint during a VM abort so leaving the PerfData objects
75 // around may also help diagnose the failure. In rare cases,
76 // PerfData objects are used in parallel with a safepoint. See
77 // the work around in PerfDataManager::destroy().
78 //
79 if (SafepointSynchronize::is_at_safepoint() && !StatSampler::is_active()) {
80 PerfDataManager::destroy();
81 }
82
83 // Remove the persistent external resources, if any. This method
84 // does not unmap or invalidate any virtual memory allocated during
85 // initialization.
86 //
87 PerfMemory::destroy();
88}
89
90void PerfMemory::initialize() {
91
92 if (is_initialized())
93 // initialization already performed
94 return;
95
96 size_t capacity = align_up(PerfDataMemorySize,
97 os::vm_allocation_granularity());
98
99 log_debug(perf, memops)("PerfDataMemorySize = " SIZE_FORMAT ","
100 " os::vm_allocation_granularity = %d,"
101 " adjusted size = " SIZE_FORMAT,
102 PerfDataMemorySize,
103 os::vm_allocation_granularity(),
104 capacity);
105
106 // allocate PerfData memory region
107 create_memory_region(capacity);
108
109 if (_start == NULL) {
110
111 // the PerfMemory region could not be created as desired. Rather
112 // than terminating the JVM, we revert to creating the instrumentation
113 // on the C heap. When running in this mode, external monitoring
114 // clients cannot attach to and monitor this JVM.
115 //
116 // the warning is issued only in debug mode in order to avoid
117 // additional output to the stdout or stderr output streams.
118 //
119 if (PrintMiscellaneous && Verbose) {
120 warning("Could not create PerfData Memory region, reverting to malloc");
121 }
122
123 _prologue = NEW_C_HEAP_OBJ(PerfDataPrologue, mtInternal);
124 }
125 else {
126
127 // the PerfMemory region was created as expected.
128
129 log_debug(perf, memops)("PerfMemory created: address = " INTPTR_FORMAT ","
130 " size = " SIZE_FORMAT,
131 p2i(_start),
132 _capacity);
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 (!is_usable()) 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 _destroyed = true;
201}
202
203// allocate an aligned block of memory from the PerfData memory
204// region. This method assumes that the PerfData memory region
205// was aligned on a double word boundary when created.
206//
207char* PerfMemory::alloc(size_t size) {
208
209 if (!UsePerfData) return NULL;
210
211 MutexLocker ml(PerfDataMemAlloc_lock);
212
213 assert(is_usable(), "called before init or after destroy");
214
215 // check that there is enough memory for this request
216 if ((_top + size) >= _end) {
217
218 _prologue->overflow += (jint)size;
219
220 return NULL;
221 }
222
223 char* result = _top;
224
225 _top += size;
226
227 assert(contains(result), "PerfData memory pointer out of range");
228
229 _prologue->used = (jint)used();
230 _prologue->num_entries = _prologue->num_entries + 1;
231
232 return result;
233}
234
235void PerfMemory::mark_updated() {
236 if (!UsePerfData) return;
237
238 assert(is_usable(), "called before init or after destroy");
239
240 _prologue->mod_time_stamp = os::elapsed_counter();
241}
242
243// Returns the complete path including the file name of performance data file.
244// Caller is expected to release the allocated memory.
245char* PerfMemory::get_perfdata_file_path() {
246 char* dest_file = NULL;
247
248 if (PerfDataSaveFile != NULL) {
249 // dest_file_name stores the validated file name if file_name
250 // contains %p which will be replaced by pid.
251 dest_file = NEW_C_HEAP_ARRAY(char, JVM_MAXPATHLEN, mtInternal);
252 if(!Arguments::copy_expand_pid(PerfDataSaveFile, strlen(PerfDataSaveFile),
253 dest_file, JVM_MAXPATHLEN)) {
254 FREE_C_HEAP_ARRAY(char, dest_file);
255 if (PrintMiscellaneous && Verbose) {
256 warning("Invalid performance data file path name specified, "\
257 "fall back to a default name");
258 }
259 } else {
260 return dest_file;
261 }
262 }
263 // create the name of the file for retaining the instrumentation memory.
264 dest_file = NEW_C_HEAP_ARRAY(char, PERFDATA_FILENAME_LEN, mtInternal);
265 jio_snprintf(dest_file, PERFDATA_FILENAME_LEN,
266 "%s_%d", PERFDATA_NAME, os::current_process_id());
267
268 return dest_file;
269}
270
271bool PerfMemory::is_initialized() {
272 return OrderAccess::load_acquire(&_initialized) != 0;
273}
274