Thu, 27 Jan 2011 16:11:27 -0800
6990754: Use native memory and reference counting to implement SymbolTable
Summary: move symbols from permgen into C heap and reference count them
Reviewed-by: never, acorn, jmasa, stefank
1 /*
2 * Copyright (c) 1997, 2010, 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 */
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/icBuffer.hpp"
31 #include "code/vtableStubs.hpp"
32 #include "gc_implementation/shared/vmGCOperations.hpp"
33 #include "interpreter/interpreter.hpp"
34 #include "memory/allocation.inline.hpp"
35 #include "oops/oop.inline.hpp"
36 #include "prims/jvm.h"
37 #include "prims/jvm_misc.hpp"
38 #include "prims/privilegedStack.hpp"
39 #include "runtime/arguments.hpp"
40 #include "runtime/frame.inline.hpp"
41 #include "runtime/interfaceSupport.hpp"
42 #include "runtime/java.hpp"
43 #include "runtime/javaCalls.hpp"
44 #include "runtime/mutexLocker.hpp"
45 #include "runtime/os.hpp"
46 #include "runtime/stubRoutines.hpp"
47 #include "services/attachListener.hpp"
48 #include "services/threadService.hpp"
49 #include "utilities/defaultStream.hpp"
50 #include "utilities/events.hpp"
51 #ifdef TARGET_OS_FAMILY_linux
52 # include "os_linux.inline.hpp"
53 # include "thread_linux.inline.hpp"
54 #endif
55 #ifdef TARGET_OS_FAMILY_solaris
56 # include "os_solaris.inline.hpp"
57 # include "thread_solaris.inline.hpp"
58 #endif
59 #ifdef TARGET_OS_FAMILY_windows
60 # include "os_windows.inline.hpp"
61 # include "thread_windows.inline.hpp"
62 #endif
64 # include <signal.h>
66 OSThread* os::_starting_thread = NULL;
67 address os::_polling_page = NULL;
68 volatile int32_t* os::_mem_serialize_page = NULL;
69 uintptr_t os::_serialize_page_mask = 0;
70 long os::_rand_seed = 1;
71 int os::_processor_count = 0;
72 size_t os::_page_sizes[os::page_sizes_max];
74 #ifndef PRODUCT
75 int os::num_mallocs = 0; // # of calls to malloc/realloc
76 size_t os::alloc_bytes = 0; // # of bytes allocated
77 int os::num_frees = 0; // # of calls to free
78 #endif
80 // Fill in buffer with current local time as an ISO-8601 string.
81 // E.g., yyyy-mm-ddThh:mm:ss-zzzz.
82 // Returns buffer, or NULL if it failed.
83 // This would mostly be a call to
84 // strftime(...., "%Y-%m-%d" "T" "%H:%M:%S" "%z", ....)
85 // except that on Windows the %z behaves badly, so we do it ourselves.
86 // Also, people wanted milliseconds on there,
87 // and strftime doesn't do milliseconds.
88 char* os::iso8601_time(char* buffer, size_t buffer_length) {
89 // Output will be of the form "YYYY-MM-DDThh:mm:ss.mmm+zzzz\0"
90 // 1 2
91 // 12345678901234567890123456789
92 static const char* iso8601_format =
93 "%04d-%02d-%02dT%02d:%02d:%02d.%03d%c%02d%02d";
94 static const size_t needed_buffer = 29;
96 // Sanity check the arguments
97 if (buffer == NULL) {
98 assert(false, "NULL buffer");
99 return NULL;
100 }
101 if (buffer_length < needed_buffer) {
102 assert(false, "buffer_length too small");
103 return NULL;
104 }
105 // Get the current time
106 jlong milliseconds_since_19700101 = javaTimeMillis();
107 const int milliseconds_per_microsecond = 1000;
108 const time_t seconds_since_19700101 =
109 milliseconds_since_19700101 / milliseconds_per_microsecond;
110 const int milliseconds_after_second =
111 milliseconds_since_19700101 % milliseconds_per_microsecond;
112 // Convert the time value to a tm and timezone variable
113 struct tm time_struct;
114 if (localtime_pd(&seconds_since_19700101, &time_struct) == NULL) {
115 assert(false, "Failed localtime_pd");
116 return NULL;
117 }
118 const time_t zone = timezone;
120 // If daylight savings time is in effect,
121 // we are 1 hour East of our time zone
122 const time_t seconds_per_minute = 60;
123 const time_t minutes_per_hour = 60;
124 const time_t seconds_per_hour = seconds_per_minute * minutes_per_hour;
125 time_t UTC_to_local = zone;
126 if (time_struct.tm_isdst > 0) {
127 UTC_to_local = UTC_to_local - seconds_per_hour;
128 }
129 // Compute the time zone offset.
130 // localtime_pd() sets timezone to the difference (in seconds)
131 // between UTC and and local time.
132 // ISO 8601 says we need the difference between local time and UTC,
133 // we change the sign of the localtime_pd() result.
134 const time_t local_to_UTC = -(UTC_to_local);
135 // Then we have to figure out if if we are ahead (+) or behind (-) UTC.
136 char sign_local_to_UTC = '+';
137 time_t abs_local_to_UTC = local_to_UTC;
138 if (local_to_UTC < 0) {
139 sign_local_to_UTC = '-';
140 abs_local_to_UTC = -(abs_local_to_UTC);
141 }
142 // Convert time zone offset seconds to hours and minutes.
143 const time_t zone_hours = (abs_local_to_UTC / seconds_per_hour);
144 const time_t zone_min =
145 ((abs_local_to_UTC % seconds_per_hour) / seconds_per_minute);
147 // Print an ISO 8601 date and time stamp into the buffer
148 const int year = 1900 + time_struct.tm_year;
149 const int month = 1 + time_struct.tm_mon;
150 const int printed = jio_snprintf(buffer, buffer_length, iso8601_format,
151 year,
152 month,
153 time_struct.tm_mday,
154 time_struct.tm_hour,
155 time_struct.tm_min,
156 time_struct.tm_sec,
157 milliseconds_after_second,
158 sign_local_to_UTC,
159 zone_hours,
160 zone_min);
161 if (printed == 0) {
162 assert(false, "Failed jio_printf");
163 return NULL;
164 }
165 return buffer;
166 }
168 OSReturn os::set_priority(Thread* thread, ThreadPriority p) {
169 #ifdef ASSERT
170 if (!(!thread->is_Java_thread() ||
171 Thread::current() == thread ||
172 Threads_lock->owned_by_self()
173 || thread->is_Compiler_thread()
174 )) {
175 assert(false, "possibility of dangling Thread pointer");
176 }
177 #endif
179 if (p >= MinPriority && p <= MaxPriority) {
180 int priority = java_to_os_priority[p];
181 return set_native_priority(thread, priority);
182 } else {
183 assert(false, "Should not happen");
184 return OS_ERR;
185 }
186 }
189 OSReturn os::get_priority(const Thread* const thread, ThreadPriority& priority) {
190 int p;
191 int os_prio;
192 OSReturn ret = get_native_priority(thread, &os_prio);
193 if (ret != OS_OK) return ret;
195 for (p = MaxPriority; p > MinPriority && java_to_os_priority[p] > os_prio; p--) ;
196 priority = (ThreadPriority)p;
197 return OS_OK;
198 }
201 // --------------------- sun.misc.Signal (optional) ---------------------
204 // SIGBREAK is sent by the keyboard to query the VM state
205 #ifndef SIGBREAK
206 #define SIGBREAK SIGQUIT
207 #endif
209 // sigexitnum_pd is a platform-specific special signal used for terminating the Signal thread.
212 static void signal_thread_entry(JavaThread* thread, TRAPS) {
213 os::set_priority(thread, NearMaxPriority);
214 while (true) {
215 int sig;
216 {
217 // FIXME : Currently we have not decieded what should be the status
218 // for this java thread blocked here. Once we decide about
219 // that we should fix this.
220 sig = os::signal_wait();
221 }
222 if (sig == os::sigexitnum_pd()) {
223 // Terminate the signal thread
224 return;
225 }
227 switch (sig) {
228 case SIGBREAK: {
229 // Check if the signal is a trigger to start the Attach Listener - in that
230 // case don't print stack traces.
231 if (!DisableAttachMechanism && AttachListener::is_init_trigger()) {
232 continue;
233 }
234 // Print stack traces
235 // Any SIGBREAK operations added here should make sure to flush
236 // the output stream (e.g. tty->flush()) after output. See 4803766.
237 // Each module also prints an extra carriage return after its output.
238 VM_PrintThreads op;
239 VMThread::execute(&op);
240 VM_PrintJNI jni_op;
241 VMThread::execute(&jni_op);
242 VM_FindDeadlocks op1(tty);
243 VMThread::execute(&op1);
244 Universe::print_heap_at_SIGBREAK();
245 if (PrintClassHistogram) {
246 VM_GC_HeapInspection op1(gclog_or_tty, true /* force full GC before heap inspection */,
247 true /* need_prologue */);
248 VMThread::execute(&op1);
249 }
250 if (JvmtiExport::should_post_data_dump()) {
251 JvmtiExport::post_data_dump();
252 }
253 break;
254 }
255 default: {
256 // Dispatch the signal to java
257 HandleMark hm(THREAD);
258 klassOop k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_Signal(), THREAD);
259 KlassHandle klass (THREAD, k);
260 if (klass.not_null()) {
261 JavaValue result(T_VOID);
262 JavaCallArguments args;
263 args.push_int(sig);
264 JavaCalls::call_static(
265 &result,
266 klass,
267 vmSymbols::dispatch_name(),
268 vmSymbols::int_void_signature(),
269 &args,
270 THREAD
271 );
272 }
273 if (HAS_PENDING_EXCEPTION) {
274 // tty is initialized early so we don't expect it to be null, but
275 // if it is we can't risk doing an initialization that might
276 // trigger additional out-of-memory conditions
277 if (tty != NULL) {
278 char klass_name[256];
279 char tmp_sig_name[16];
280 const char* sig_name = "UNKNOWN";
281 instanceKlass::cast(PENDING_EXCEPTION->klass())->
282 name()->as_klass_external_name(klass_name, 256);
283 if (os::exception_name(sig, tmp_sig_name, 16) != NULL)
284 sig_name = tmp_sig_name;
285 warning("Exception %s occurred dispatching signal %s to handler"
286 "- the VM may need to be forcibly terminated",
287 klass_name, sig_name );
288 }
289 CLEAR_PENDING_EXCEPTION;
290 }
291 }
292 }
293 }
294 }
297 void os::signal_init() {
298 if (!ReduceSignalUsage) {
299 // Setup JavaThread for processing signals
300 EXCEPTION_MARK;
301 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
302 instanceKlassHandle klass (THREAD, k);
303 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
305 const char thread_name[] = "Signal Dispatcher";
306 Handle string = java_lang_String::create_from_str(thread_name, CHECK);
308 // Initialize thread_oop to put it into the system threadGroup
309 Handle thread_group (THREAD, Universe::system_thread_group());
310 JavaValue result(T_VOID);
311 JavaCalls::call_special(&result, thread_oop,
312 klass,
313 vmSymbols::object_initializer_name(),
314 vmSymbols::threadgroup_string_void_signature(),
315 thread_group,
316 string,
317 CHECK);
319 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
320 JavaCalls::call_special(&result,
321 thread_group,
322 group,
323 vmSymbols::add_method_name(),
324 vmSymbols::thread_void_signature(),
325 thread_oop, // ARG 1
326 CHECK);
328 os::signal_init_pd();
330 { MutexLocker mu(Threads_lock);
331 JavaThread* signal_thread = new JavaThread(&signal_thread_entry);
333 // At this point it may be possible that no osthread was created for the
334 // JavaThread due to lack of memory. We would have to throw an exception
335 // in that case. However, since this must work and we do not allow
336 // exceptions anyway, check and abort if this fails.
337 if (signal_thread == NULL || signal_thread->osthread() == NULL) {
338 vm_exit_during_initialization("java.lang.OutOfMemoryError",
339 "unable to create new native thread");
340 }
342 java_lang_Thread::set_thread(thread_oop(), signal_thread);
343 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
344 java_lang_Thread::set_daemon(thread_oop());
346 signal_thread->set_threadObj(thread_oop());
347 Threads::add(signal_thread);
348 Thread::start(signal_thread);
349 }
350 // Handle ^BREAK
351 os::signal(SIGBREAK, os::user_handler());
352 }
353 }
356 void os::terminate_signal_thread() {
357 if (!ReduceSignalUsage)
358 signal_notify(sigexitnum_pd());
359 }
362 // --------------------- loading libraries ---------------------
364 typedef jint (JNICALL *JNI_OnLoad_t)(JavaVM *, void *);
365 extern struct JavaVM_ main_vm;
367 static void* _native_java_library = NULL;
369 void* os::native_java_library() {
370 if (_native_java_library == NULL) {
371 char buffer[JVM_MAXPATHLEN];
372 char ebuf[1024];
374 // Try to load verify dll first. In 1.3 java dll depends on it and is not
375 // always able to find it when the loading executable is outside the JDK.
376 // In order to keep working with 1.2 we ignore any loading errors.
377 dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), "verify");
378 dll_load(buffer, ebuf, sizeof(ebuf));
380 // Load java dll
381 dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), "java");
382 _native_java_library = dll_load(buffer, ebuf, sizeof(ebuf));
383 if (_native_java_library == NULL) {
384 vm_exit_during_initialization("Unable to load native library", ebuf);
385 }
386 }
387 static jboolean onLoaded = JNI_FALSE;
388 if (onLoaded) {
389 // We may have to wait to fire OnLoad until TLS is initialized.
390 if (ThreadLocalStorage::is_initialized()) {
391 // The JNI_OnLoad handling is normally done by method load in
392 // java.lang.ClassLoader$NativeLibrary, but the VM loads the base library
393 // explicitly so we have to check for JNI_OnLoad as well
394 const char *onLoadSymbols[] = JNI_ONLOAD_SYMBOLS;
395 JNI_OnLoad_t JNI_OnLoad = CAST_TO_FN_PTR(
396 JNI_OnLoad_t, dll_lookup(_native_java_library, onLoadSymbols[0]));
397 if (JNI_OnLoad != NULL) {
398 JavaThread* thread = JavaThread::current();
399 ThreadToNativeFromVM ttn(thread);
400 HandleMark hm(thread);
401 jint ver = (*JNI_OnLoad)(&main_vm, NULL);
402 onLoaded = JNI_TRUE;
403 if (!Threads::is_supported_jni_version_including_1_1(ver)) {
404 vm_exit_during_initialization("Unsupported JNI version");
405 }
406 }
407 }
408 }
409 return _native_java_library;
410 }
412 // --------------------- heap allocation utilities ---------------------
414 char *os::strdup(const char *str) {
415 size_t size = strlen(str);
416 char *dup_str = (char *)malloc(size + 1);
417 if (dup_str == NULL) return NULL;
418 strcpy(dup_str, str);
419 return dup_str;
420 }
424 #ifdef ASSERT
425 #define space_before (MallocCushion + sizeof(double))
426 #define space_after MallocCushion
427 #define size_addr_from_base(p) (size_t*)(p + space_before - sizeof(size_t))
428 #define size_addr_from_obj(p) ((size_t*)p - 1)
429 // MallocCushion: size of extra cushion allocated around objects with +UseMallocOnly
430 // NB: cannot be debug variable, because these aren't set from the command line until
431 // *after* the first few allocs already happened
432 #define MallocCushion 16
433 #else
434 #define space_before 0
435 #define space_after 0
436 #define size_addr_from_base(p) should not use w/o ASSERT
437 #define size_addr_from_obj(p) should not use w/o ASSERT
438 #define MallocCushion 0
439 #endif
440 #define paranoid 0 /* only set to 1 if you suspect checking code has bug */
442 #ifdef ASSERT
443 inline size_t get_size(void* obj) {
444 size_t size = *size_addr_from_obj(obj);
445 if (size < 0) {
446 fatal(err_msg("free: size field of object #" PTR_FORMAT " was overwritten ("
447 SIZE_FORMAT ")", obj, size));
448 }
449 return size;
450 }
452 u_char* find_cushion_backwards(u_char* start) {
453 u_char* p = start;
454 while (p[ 0] != badResourceValue || p[-1] != badResourceValue ||
455 p[-2] != badResourceValue || p[-3] != badResourceValue) p--;
456 // ok, we have four consecutive marker bytes; find start
457 u_char* q = p - 4;
458 while (*q == badResourceValue) q--;
459 return q + 1;
460 }
462 u_char* find_cushion_forwards(u_char* start) {
463 u_char* p = start;
464 while (p[0] != badResourceValue || p[1] != badResourceValue ||
465 p[2] != badResourceValue || p[3] != badResourceValue) p++;
466 // ok, we have four consecutive marker bytes; find end of cushion
467 u_char* q = p + 4;
468 while (*q == badResourceValue) q++;
469 return q - MallocCushion;
470 }
472 void print_neighbor_blocks(void* ptr) {
473 // find block allocated before ptr (not entirely crash-proof)
474 if (MallocCushion < 4) {
475 tty->print_cr("### cannot find previous block (MallocCushion < 4)");
476 return;
477 }
478 u_char* start_of_this_block = (u_char*)ptr - space_before;
479 u_char* end_of_prev_block_data = start_of_this_block - space_after -1;
480 // look for cushion in front of prev. block
481 u_char* start_of_prev_block = find_cushion_backwards(end_of_prev_block_data);
482 ptrdiff_t size = *size_addr_from_base(start_of_prev_block);
483 u_char* obj = start_of_prev_block + space_before;
484 if (size <= 0 ) {
485 // start is bad; mayhave been confused by OS data inbetween objects
486 // search one more backwards
487 start_of_prev_block = find_cushion_backwards(start_of_prev_block);
488 size = *size_addr_from_base(start_of_prev_block);
489 obj = start_of_prev_block + space_before;
490 }
492 if (start_of_prev_block + space_before + size + space_after == start_of_this_block) {
493 tty->print_cr("### previous object: %p (%ld bytes)", obj, size);
494 } else {
495 tty->print_cr("### previous object (not sure if correct): %p (%ld bytes)", obj, size);
496 }
498 // now find successor block
499 u_char* start_of_next_block = (u_char*)ptr + *size_addr_from_obj(ptr) + space_after;
500 start_of_next_block = find_cushion_forwards(start_of_next_block);
501 u_char* next_obj = start_of_next_block + space_before;
502 ptrdiff_t next_size = *size_addr_from_base(start_of_next_block);
503 if (start_of_next_block[0] == badResourceValue &&
504 start_of_next_block[1] == badResourceValue &&
505 start_of_next_block[2] == badResourceValue &&
506 start_of_next_block[3] == badResourceValue) {
507 tty->print_cr("### next object: %p (%ld bytes)", next_obj, next_size);
508 } else {
509 tty->print_cr("### next object (not sure if correct): %p (%ld bytes)", next_obj, next_size);
510 }
511 }
514 void report_heap_error(void* memblock, void* bad, const char* where) {
515 tty->print_cr("## nof_mallocs = %d, nof_frees = %d", os::num_mallocs, os::num_frees);
516 tty->print_cr("## memory stomp: byte at %p %s object %p", bad, where, memblock);
517 print_neighbor_blocks(memblock);
518 fatal("memory stomping error");
519 }
521 void verify_block(void* memblock) {
522 size_t size = get_size(memblock);
523 if (MallocCushion) {
524 u_char* ptr = (u_char*)memblock - space_before;
525 for (int i = 0; i < MallocCushion; i++) {
526 if (ptr[i] != badResourceValue) {
527 report_heap_error(memblock, ptr+i, "in front of");
528 }
529 }
530 u_char* end = (u_char*)memblock + size + space_after;
531 for (int j = -MallocCushion; j < 0; j++) {
532 if (end[j] != badResourceValue) {
533 report_heap_error(memblock, end+j, "after");
534 }
535 }
536 }
537 }
538 #endif
540 void* os::malloc(size_t size) {
541 NOT_PRODUCT(num_mallocs++);
542 NOT_PRODUCT(alloc_bytes += size);
544 if (size == 0) {
545 // return a valid pointer if size is zero
546 // if NULL is returned the calling functions assume out of memory.
547 size = 1;
548 }
550 NOT_PRODUCT(if (MallocVerifyInterval > 0) check_heap());
551 u_char* ptr = (u_char*)::malloc(size + space_before + space_after);
552 #ifdef ASSERT
553 if (ptr == NULL) return NULL;
554 if (MallocCushion) {
555 for (u_char* p = ptr; p < ptr + MallocCushion; p++) *p = (u_char)badResourceValue;
556 u_char* end = ptr + space_before + size;
557 for (u_char* pq = ptr+MallocCushion; pq < end; pq++) *pq = (u_char)uninitBlockPad;
558 for (u_char* q = end; q < end + MallocCushion; q++) *q = (u_char)badResourceValue;
559 }
560 // put size just before data
561 *size_addr_from_base(ptr) = size;
562 #endif
563 u_char* memblock = ptr + space_before;
564 if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
565 tty->print_cr("os::malloc caught, %lu bytes --> %p", size, memblock);
566 breakpoint();
567 }
568 debug_only(if (paranoid) verify_block(memblock));
569 if (PrintMalloc && tty != NULL) tty->print_cr("os::malloc %lu bytes --> %p", size, memblock);
570 return memblock;
571 }
574 void* os::realloc(void *memblock, size_t size) {
575 NOT_PRODUCT(num_mallocs++);
576 NOT_PRODUCT(alloc_bytes += size);
577 #ifndef ASSERT
578 return ::realloc(memblock, size);
579 #else
580 if (memblock == NULL) {
581 return os::malloc(size);
582 }
583 if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
584 tty->print_cr("os::realloc caught %p", memblock);
585 breakpoint();
586 }
587 verify_block(memblock);
588 NOT_PRODUCT(if (MallocVerifyInterval > 0) check_heap());
589 if (size == 0) return NULL;
590 // always move the block
591 void* ptr = malloc(size);
592 if (PrintMalloc) tty->print_cr("os::remalloc %lu bytes, %p --> %p", size, memblock, ptr);
593 // Copy to new memory if malloc didn't fail
594 if ( ptr != NULL ) {
595 memcpy(ptr, memblock, MIN2(size, get_size(memblock)));
596 if (paranoid) verify_block(ptr);
597 if ((intptr_t)ptr == (intptr_t)MallocCatchPtr) {
598 tty->print_cr("os::realloc caught, %lu bytes --> %p", size, ptr);
599 breakpoint();
600 }
601 free(memblock);
602 }
603 return ptr;
604 #endif
605 }
608 void os::free(void *memblock) {
609 NOT_PRODUCT(num_frees++);
610 #ifdef ASSERT
611 if (memblock == NULL) return;
612 if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
613 if (tty != NULL) tty->print_cr("os::free caught %p", memblock);
614 breakpoint();
615 }
616 verify_block(memblock);
617 if (PrintMalloc && tty != NULL)
618 // tty->print_cr("os::free %p", memblock);
619 fprintf(stderr, "os::free %p\n", memblock);
620 NOT_PRODUCT(if (MallocVerifyInterval > 0) check_heap());
621 // Added by detlefs.
622 if (MallocCushion) {
623 u_char* ptr = (u_char*)memblock - space_before;
624 for (u_char* p = ptr; p < ptr + MallocCushion; p++) {
625 guarantee(*p == badResourceValue,
626 "Thing freed should be malloc result.");
627 *p = (u_char)freeBlockPad;
628 }
629 size_t size = get_size(memblock);
630 u_char* end = ptr + space_before + size;
631 for (u_char* q = end; q < end + MallocCushion; q++) {
632 guarantee(*q == badResourceValue,
633 "Thing freed should be malloc result.");
634 *q = (u_char)freeBlockPad;
635 }
636 }
637 #endif
638 ::free((char*)memblock - space_before);
639 }
641 void os::init_random(long initval) {
642 _rand_seed = initval;
643 }
646 long os::random() {
647 /* standard, well-known linear congruential random generator with
648 * next_rand = (16807*seed) mod (2**31-1)
649 * see
650 * (1) "Random Number Generators: Good Ones Are Hard to Find",
651 * S.K. Park and K.W. Miller, Communications of the ACM 31:10 (Oct 1988),
652 * (2) "Two Fast Implementations of the 'Minimal Standard' Random
653 * Number Generator", David G. Carta, Comm. ACM 33, 1 (Jan 1990), pp. 87-88.
654 */
655 const long a = 16807;
656 const unsigned long m = 2147483647;
657 const long q = m / a; assert(q == 127773, "weird math");
658 const long r = m % a; assert(r == 2836, "weird math");
660 // compute az=2^31p+q
661 unsigned long lo = a * (long)(_rand_seed & 0xFFFF);
662 unsigned long hi = a * (long)((unsigned long)_rand_seed >> 16);
663 lo += (hi & 0x7FFF) << 16;
665 // if q overflowed, ignore the overflow and increment q
666 if (lo > m) {
667 lo &= m;
668 ++lo;
669 }
670 lo += hi >> 15;
672 // if (p+q) overflowed, ignore the overflow and increment (p+q)
673 if (lo > m) {
674 lo &= m;
675 ++lo;
676 }
677 return (_rand_seed = lo);
678 }
680 // The INITIALIZED state is distinguished from the SUSPENDED state because the
681 // conditions in which a thread is first started are different from those in which
682 // a suspension is resumed. These differences make it hard for us to apply the
683 // tougher checks when starting threads that we want to do when resuming them.
684 // However, when start_thread is called as a result of Thread.start, on a Java
685 // thread, the operation is synchronized on the Java Thread object. So there
686 // cannot be a race to start the thread and hence for the thread to exit while
687 // we are working on it. Non-Java threads that start Java threads either have
688 // to do so in a context in which races are impossible, or should do appropriate
689 // locking.
691 void os::start_thread(Thread* thread) {
692 // guard suspend/resume
693 MutexLockerEx ml(thread->SR_lock(), Mutex::_no_safepoint_check_flag);
694 OSThread* osthread = thread->osthread();
695 osthread->set_state(RUNNABLE);
696 pd_start_thread(thread);
697 }
699 //---------------------------------------------------------------------------
700 // Helper functions for fatal error handler
702 void os::print_hex_dump(outputStream* st, address start, address end, int unitsize) {
703 assert(unitsize == 1 || unitsize == 2 || unitsize == 4 || unitsize == 8, "just checking");
705 int cols = 0;
706 int cols_per_line = 0;
707 switch (unitsize) {
708 case 1: cols_per_line = 16; break;
709 case 2: cols_per_line = 8; break;
710 case 4: cols_per_line = 4; break;
711 case 8: cols_per_line = 2; break;
712 default: return;
713 }
715 address p = start;
716 st->print(PTR_FORMAT ": ", start);
717 while (p < end) {
718 switch (unitsize) {
719 case 1: st->print("%02x", *(u1*)p); break;
720 case 2: st->print("%04x", *(u2*)p); break;
721 case 4: st->print("%08x", *(u4*)p); break;
722 case 8: st->print("%016" FORMAT64_MODIFIER "x", *(u8*)p); break;
723 }
724 p += unitsize;
725 cols++;
726 if (cols >= cols_per_line && p < end) {
727 cols = 0;
728 st->cr();
729 st->print(PTR_FORMAT ": ", p);
730 } else {
731 st->print(" ");
732 }
733 }
734 st->cr();
735 }
737 void os::print_environment_variables(outputStream* st, const char** env_list,
738 char* buffer, int len) {
739 if (env_list) {
740 st->print_cr("Environment Variables:");
742 for (int i = 0; env_list[i] != NULL; i++) {
743 if (getenv(env_list[i], buffer, len)) {
744 st->print(env_list[i]);
745 st->print("=");
746 st->print_cr(buffer);
747 }
748 }
749 }
750 }
752 void os::print_cpu_info(outputStream* st) {
753 // cpu
754 st->print("CPU:");
755 st->print("total %d", os::processor_count());
756 // It's not safe to query number of active processors after crash
757 // st->print("(active %d)", os::active_processor_count());
758 st->print(" %s", VM_Version::cpu_features());
759 st->cr();
760 }
762 void os::print_date_and_time(outputStream *st) {
763 time_t tloc;
764 (void)time(&tloc);
765 st->print("time: %s", ctime(&tloc)); // ctime adds newline.
767 double t = os::elapsedTime();
768 // NOTE: It tends to crash after a SEGV if we want to printf("%f",...) in
769 // Linux. Must be a bug in glibc ? Workaround is to round "t" to int
770 // before printf. We lost some precision, but who cares?
771 st->print_cr("elapsed time: %d seconds", (int)t);
772 }
774 // moved from debug.cpp (used to be find()) but still called from there
775 // The verbose parameter is only set by the debug code in one case
776 void os::print_location(outputStream* st, intptr_t x, bool verbose) {
777 address addr = (address)x;
778 CodeBlob* b = CodeCache::find_blob_unsafe(addr);
779 if (b != NULL) {
780 if (b->is_buffer_blob()) {
781 // the interpreter is generated into a buffer blob
782 InterpreterCodelet* i = Interpreter::codelet_containing(addr);
783 if (i != NULL) {
784 st->print_cr(INTPTR_FORMAT " is an Interpreter codelet", addr);
785 i->print_on(st);
786 return;
787 }
788 if (Interpreter::contains(addr)) {
789 st->print_cr(INTPTR_FORMAT " is pointing into interpreter code"
790 " (not bytecode specific)", addr);
791 return;
792 }
793 //
794 if (AdapterHandlerLibrary::contains(b)) {
795 st->print_cr(INTPTR_FORMAT " is an AdapterHandler", addr);
796 AdapterHandlerLibrary::print_handler_on(st, b);
797 }
798 // the stubroutines are generated into a buffer blob
799 StubCodeDesc* d = StubCodeDesc::desc_for(addr);
800 if (d != NULL) {
801 d->print_on(st);
802 if (verbose) st->cr();
803 return;
804 }
805 if (StubRoutines::contains(addr)) {
806 st->print_cr(INTPTR_FORMAT " is pointing to an (unnamed) "
807 "stub routine", addr);
808 return;
809 }
810 // the InlineCacheBuffer is using stubs generated into a buffer blob
811 if (InlineCacheBuffer::contains(addr)) {
812 st->print_cr(INTPTR_FORMAT " is pointing into InlineCacheBuffer", addr);
813 return;
814 }
815 VtableStub* v = VtableStubs::stub_containing(addr);
816 if (v != NULL) {
817 v->print_on(st);
818 return;
819 }
820 }
821 if (verbose && b->is_nmethod()) {
822 ResourceMark rm;
823 st->print("%#p: Compiled ", addr);
824 ((nmethod*)b)->method()->print_value_on(st);
825 st->print(" = (CodeBlob*)" INTPTR_FORMAT, b);
826 st->cr();
827 return;
828 }
829 st->print(INTPTR_FORMAT " ", b);
830 if ( b->is_nmethod()) {
831 if (b->is_zombie()) {
832 st->print_cr("is zombie nmethod");
833 } else if (b->is_not_entrant()) {
834 st->print_cr("is non-entrant nmethod");
835 }
836 }
837 b->print_on(st);
838 return;
839 }
841 if (Universe::heap()->is_in(addr)) {
842 HeapWord* p = Universe::heap()->block_start(addr);
843 bool print = false;
844 // If we couldn't find it it just may mean that heap wasn't parseable
845 // See if we were just given an oop directly
846 if (p != NULL && Universe::heap()->block_is_obj(p)) {
847 print = true;
848 } else if (p == NULL && ((oopDesc*)addr)->is_oop()) {
849 p = (HeapWord*) addr;
850 print = true;
851 }
852 if (print) {
853 st->print_cr(INTPTR_FORMAT " is an oop", addr);
854 oop(p)->print_on(st);
855 if (p != (HeapWord*)x && oop(p)->is_constMethod() &&
856 constMethodOop(p)->contains(addr)) {
857 Thread *thread = Thread::current();
858 HandleMark hm(thread);
859 methodHandle mh (thread, constMethodOop(p)->method());
860 if (!mh->is_native()) {
861 st->print_cr("bci_from(%p) = %d; print_codes():",
862 addr, mh->bci_from(address(x)));
863 mh->print_codes_on(st);
864 }
865 }
866 return;
867 }
868 } else {
869 if (Universe::heap()->is_in_reserved(addr)) {
870 st->print_cr(INTPTR_FORMAT " is an unallocated location "
871 "in the heap", addr);
872 return;
873 }
874 }
875 if (JNIHandles::is_global_handle((jobject) addr)) {
876 st->print_cr(INTPTR_FORMAT " is a global jni handle", addr);
877 return;
878 }
879 if (JNIHandles::is_weak_global_handle((jobject) addr)) {
880 st->print_cr(INTPTR_FORMAT " is a weak global jni handle", addr);
881 return;
882 }
883 #ifndef PRODUCT
884 // we don't keep the block list in product mode
885 if (JNIHandleBlock::any_contains((jobject) addr)) {
886 st->print_cr(INTPTR_FORMAT " is a local jni handle", addr);
887 return;
888 }
889 #endif
891 for(JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
892 // Check for privilege stack
893 if (thread->privileged_stack_top() != NULL &&
894 thread->privileged_stack_top()->contains(addr)) {
895 st->print_cr(INTPTR_FORMAT " is pointing into the privilege stack "
896 "for thread: " INTPTR_FORMAT, addr, thread);
897 if (verbose) thread->print_on(st);
898 return;
899 }
900 // If the addr is a java thread print information about that.
901 if (addr == (address)thread) {
902 if (verbose) {
903 thread->print_on(st);
904 } else {
905 st->print_cr(INTPTR_FORMAT " is a thread", addr);
906 }
907 return;
908 }
909 // If the addr is in the stack region for this thread then report that
910 // and print thread info
911 if (thread->stack_base() >= addr &&
912 addr > (thread->stack_base() - thread->stack_size())) {
913 st->print_cr(INTPTR_FORMAT " is pointing into the stack for thread: "
914 INTPTR_FORMAT, addr, thread);
915 if (verbose) thread->print_on(st);
916 return;
917 }
919 }
920 // Try an OS specific find
921 if (os::find(addr, st)) {
922 return;
923 }
925 st->print_cr(INTPTR_FORMAT " is an unknown value", addr);
926 }
928 // Looks like all platforms except IA64 can use the same function to check
929 // if C stack is walkable beyond current frame. The check for fp() is not
930 // necessary on Sparc, but it's harmless.
931 bool os::is_first_C_frame(frame* fr) {
932 #ifdef IA64
933 // In order to walk native frames on Itanium, we need to access the unwind
934 // table, which is inside ELF. We don't want to parse ELF after fatal error,
935 // so return true for IA64. If we need to support C stack walking on IA64,
936 // this function needs to be moved to CPU specific files, as fp() on IA64
937 // is register stack, which grows towards higher memory address.
938 return true;
939 #endif
941 // Load up sp, fp, sender sp and sender fp, check for reasonable values.
942 // Check usp first, because if that's bad the other accessors may fault
943 // on some architectures. Ditto ufp second, etc.
944 uintptr_t fp_align_mask = (uintptr_t)(sizeof(address)-1);
945 // sp on amd can be 32 bit aligned.
946 uintptr_t sp_align_mask = (uintptr_t)(sizeof(int)-1);
948 uintptr_t usp = (uintptr_t)fr->sp();
949 if ((usp & sp_align_mask) != 0) return true;
951 uintptr_t ufp = (uintptr_t)fr->fp();
952 if ((ufp & fp_align_mask) != 0) return true;
954 uintptr_t old_sp = (uintptr_t)fr->sender_sp();
955 if ((old_sp & sp_align_mask) != 0) return true;
956 if (old_sp == 0 || old_sp == (uintptr_t)-1) return true;
958 uintptr_t old_fp = (uintptr_t)fr->link();
959 if ((old_fp & fp_align_mask) != 0) return true;
960 if (old_fp == 0 || old_fp == (uintptr_t)-1 || old_fp == ufp) return true;
962 // stack grows downwards; if old_fp is below current fp or if the stack
963 // frame is too large, either the stack is corrupted or fp is not saved
964 // on stack (i.e. on x86, ebp may be used as general register). The stack
965 // is not walkable beyond current frame.
966 if (old_fp < ufp) return true;
967 if (old_fp - ufp > 64 * K) return true;
969 return false;
970 }
972 #ifdef ASSERT
973 extern "C" void test_random() {
974 const double m = 2147483647;
975 double mean = 0.0, variance = 0.0, t;
976 long reps = 10000;
977 unsigned long seed = 1;
979 tty->print_cr("seed %ld for %ld repeats...", seed, reps);
980 os::init_random(seed);
981 long num;
982 for (int k = 0; k < reps; k++) {
983 num = os::random();
984 double u = (double)num / m;
985 assert(u >= 0.0 && u <= 1.0, "bad random number!");
987 // calculate mean and variance of the random sequence
988 mean += u;
989 variance += (u*u);
990 }
991 mean /= reps;
992 variance /= (reps - 1);
994 assert(num == 1043618065, "bad seed");
995 tty->print_cr("mean of the 1st 10000 numbers: %f", mean);
996 tty->print_cr("variance of the 1st 10000 numbers: %f", variance);
997 const double eps = 0.0001;
998 t = fabsd(mean - 0.5018);
999 assert(t < eps, "bad mean");
1000 t = (variance - 0.3355) < 0.0 ? -(variance - 0.3355) : variance - 0.3355;
1001 assert(t < eps, "bad variance");
1002 }
1003 #endif
1006 // Set up the boot classpath.
1008 char* os::format_boot_path(const char* format_string,
1009 const char* home,
1010 int home_len,
1011 char fileSep,
1012 char pathSep) {
1013 assert((fileSep == '/' && pathSep == ':') ||
1014 (fileSep == '\\' && pathSep == ';'), "unexpected seperator chars");
1016 // Scan the format string to determine the length of the actual
1017 // boot classpath, and handle platform dependencies as well.
1018 int formatted_path_len = 0;
1019 const char* p;
1020 for (p = format_string; *p != 0; ++p) {
1021 if (*p == '%') formatted_path_len += home_len - 1;
1022 ++formatted_path_len;
1023 }
1025 char* formatted_path = NEW_C_HEAP_ARRAY(char, formatted_path_len + 1);
1026 if (formatted_path == NULL) {
1027 return NULL;
1028 }
1030 // Create boot classpath from format, substituting separator chars and
1031 // java home directory.
1032 char* q = formatted_path;
1033 for (p = format_string; *p != 0; ++p) {
1034 switch (*p) {
1035 case '%':
1036 strcpy(q, home);
1037 q += home_len;
1038 break;
1039 case '/':
1040 *q++ = fileSep;
1041 break;
1042 case ':':
1043 *q++ = pathSep;
1044 break;
1045 default:
1046 *q++ = *p;
1047 }
1048 }
1049 *q = '\0';
1051 assert((q - formatted_path) == formatted_path_len, "formatted_path size botched");
1052 return formatted_path;
1053 }
1056 bool os::set_boot_path(char fileSep, char pathSep) {
1057 const char* home = Arguments::get_java_home();
1058 int home_len = (int)strlen(home);
1060 static const char* meta_index_dir_format = "%/lib/";
1061 static const char* meta_index_format = "%/lib/meta-index";
1062 char* meta_index = format_boot_path(meta_index_format, home, home_len, fileSep, pathSep);
1063 if (meta_index == NULL) return false;
1064 char* meta_index_dir = format_boot_path(meta_index_dir_format, home, home_len, fileSep, pathSep);
1065 if (meta_index_dir == NULL) return false;
1066 Arguments::set_meta_index_path(meta_index, meta_index_dir);
1068 // Any modification to the JAR-file list, for the boot classpath must be
1069 // aligned with install/install/make/common/Pack.gmk. Note: boot class
1070 // path class JARs, are stripped for StackMapTable to reduce download size.
1071 static const char classpath_format[] =
1072 "%/lib/resources.jar:"
1073 "%/lib/rt.jar:"
1074 "%/lib/sunrsasign.jar:"
1075 "%/lib/jsse.jar:"
1076 "%/lib/jce.jar:"
1077 "%/lib/charsets.jar:"
1079 // ## TEMPORARY hack to keep the legacy launcher working when
1080 // ## only the boot module is installed (cf. j.l.ClassLoader)
1081 "%/lib/modules/jdk.boot.jar:"
1083 "%/classes";
1084 char* sysclasspath = format_boot_path(classpath_format, home, home_len, fileSep, pathSep);
1085 if (sysclasspath == NULL) return false;
1086 Arguments::set_sysclasspath(sysclasspath);
1088 return true;
1089 }
1091 /*
1092 * Splits a path, based on its separator, the number of
1093 * elements is returned back in n.
1094 * It is the callers responsibility to:
1095 * a> check the value of n, and n may be 0.
1096 * b> ignore any empty path elements
1097 * c> free up the data.
1098 */
1099 char** os::split_path(const char* path, int* n) {
1100 *n = 0;
1101 if (path == NULL || strlen(path) == 0) {
1102 return NULL;
1103 }
1104 const char psepchar = *os::path_separator();
1105 char* inpath = (char*)NEW_C_HEAP_ARRAY(char, strlen(path) + 1);
1106 if (inpath == NULL) {
1107 return NULL;
1108 }
1109 strncpy(inpath, path, strlen(path));
1110 int count = 1;
1111 char* p = strchr(inpath, psepchar);
1112 // Get a count of elements to allocate memory
1113 while (p != NULL) {
1114 count++;
1115 p++;
1116 p = strchr(p, psepchar);
1117 }
1118 char** opath = (char**) NEW_C_HEAP_ARRAY(char*, count);
1119 if (opath == NULL) {
1120 return NULL;
1121 }
1123 // do the actual splitting
1124 p = inpath;
1125 for (int i = 0 ; i < count ; i++) {
1126 size_t len = strcspn(p, os::path_separator());
1127 if (len > JVM_MAXPATHLEN) {
1128 return NULL;
1129 }
1130 // allocate the string and add terminator storage
1131 char* s = (char*)NEW_C_HEAP_ARRAY(char, len + 1);
1132 if (s == NULL) {
1133 return NULL;
1134 }
1135 strncpy(s, p, len);
1136 s[len] = '\0';
1137 opath[i] = s;
1138 p += len + 1;
1139 }
1140 FREE_C_HEAP_ARRAY(char, inpath);
1141 *n = count;
1142 return opath;
1143 }
1145 void os::set_memory_serialize_page(address page) {
1146 int count = log2_intptr(sizeof(class JavaThread)) - log2_intptr(64);
1147 _mem_serialize_page = (volatile int32_t *)page;
1148 // We initialize the serialization page shift count here
1149 // We assume a cache line size of 64 bytes
1150 assert(SerializePageShiftCount == count,
1151 "thread size changed, fix SerializePageShiftCount constant");
1152 set_serialize_page_mask((uintptr_t)(vm_page_size() - sizeof(int32_t)));
1153 }
1155 static volatile intptr_t SerializePageLock = 0;
1157 // This method is called from signal handler when SIGSEGV occurs while the current
1158 // thread tries to store to the "read-only" memory serialize page during state
1159 // transition.
1160 void os::block_on_serialize_page_trap() {
1161 if (TraceSafepoint) {
1162 tty->print_cr("Block until the serialize page permission restored");
1163 }
1164 // When VMThread is holding the SerializePageLock during modifying the
1165 // access permission of the memory serialize page, the following call
1166 // will block until the permission of that page is restored to rw.
1167 // Generally, it is unsafe to manipulate locks in signal handlers, but in
1168 // this case, it's OK as the signal is synchronous and we know precisely when
1169 // it can occur.
1170 Thread::muxAcquire(&SerializePageLock, "set_memory_serialize_page");
1171 Thread::muxRelease(&SerializePageLock);
1172 }
1174 // Serialize all thread state variables
1175 void os::serialize_thread_states() {
1176 // On some platforms such as Solaris & Linux, the time duration of the page
1177 // permission restoration is observed to be much longer than expected due to
1178 // scheduler starvation problem etc. To avoid the long synchronization
1179 // time and expensive page trap spinning, 'SerializePageLock' is used to block
1180 // the mutator thread if such case is encountered. See bug 6546278 for details.
1181 Thread::muxAcquire(&SerializePageLock, "serialize_thread_states");
1182 os::protect_memory((char *)os::get_memory_serialize_page(),
1183 os::vm_page_size(), MEM_PROT_READ);
1184 os::protect_memory((char *)os::get_memory_serialize_page(),
1185 os::vm_page_size(), MEM_PROT_RW);
1186 Thread::muxRelease(&SerializePageLock);
1187 }
1189 // Returns true if the current stack pointer is above the stack shadow
1190 // pages, false otherwise.
1192 bool os::stack_shadow_pages_available(Thread *thread, methodHandle method) {
1193 assert(StackRedPages > 0 && StackYellowPages > 0,"Sanity check");
1194 address sp = current_stack_pointer();
1195 // Check if we have StackShadowPages above the yellow zone. This parameter
1196 // is dependent on the depth of the maximum VM call stack possible from
1197 // the handler for stack overflow. 'instanceof' in the stack overflow
1198 // handler or a println uses at least 8k stack of VM and native code
1199 // respectively.
1200 const int framesize_in_bytes =
1201 Interpreter::size_top_interpreter_activation(method()) * wordSize;
1202 int reserved_area = ((StackShadowPages + StackRedPages + StackYellowPages)
1203 * vm_page_size()) + framesize_in_bytes;
1204 // The very lower end of the stack
1205 address stack_limit = thread->stack_base() - thread->stack_size();
1206 return (sp > (stack_limit + reserved_area));
1207 }
1209 size_t os::page_size_for_region(size_t region_min_size, size_t region_max_size,
1210 uint min_pages)
1211 {
1212 assert(min_pages > 0, "sanity");
1213 if (UseLargePages) {
1214 const size_t max_page_size = region_max_size / min_pages;
1216 for (unsigned int i = 0; _page_sizes[i] != 0; ++i) {
1217 const size_t sz = _page_sizes[i];
1218 const size_t mask = sz - 1;
1219 if ((region_min_size & mask) == 0 && (region_max_size & mask) == 0) {
1220 // The largest page size with no fragmentation.
1221 return sz;
1222 }
1224 if (sz <= max_page_size) {
1225 // The largest page size that satisfies the min_pages requirement.
1226 return sz;
1227 }
1228 }
1229 }
1231 return vm_page_size();
1232 }
1234 #ifndef PRODUCT
1235 void os::trace_page_sizes(const char* str, const size_t region_min_size,
1236 const size_t region_max_size, const size_t page_size,
1237 const char* base, const size_t size)
1238 {
1239 if (TracePageSizes) {
1240 tty->print_cr("%s: min=" SIZE_FORMAT " max=" SIZE_FORMAT
1241 " pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT
1242 " size=" SIZE_FORMAT,
1243 str, region_min_size, region_max_size,
1244 page_size, base, size);
1245 }
1246 }
1247 #endif // #ifndef PRODUCT
1249 // This is the working definition of a server class machine:
1250 // >= 2 physical CPU's and >=2GB of memory, with some fuzz
1251 // because the graphics memory (?) sometimes masks physical memory.
1252 // If you want to change the definition of a server class machine
1253 // on some OS or platform, e.g., >=4GB on Windohs platforms,
1254 // then you'll have to parameterize this method based on that state,
1255 // as was done for logical processors here, or replicate and
1256 // specialize this method for each platform. (Or fix os to have
1257 // some inheritance structure and use subclassing. Sigh.)
1258 // If you want some platform to always or never behave as a server
1259 // class machine, change the setting of AlwaysActAsServerClassMachine
1260 // and NeverActAsServerClassMachine in globals*.hpp.
1261 bool os::is_server_class_machine() {
1262 // First check for the early returns
1263 if (NeverActAsServerClassMachine) {
1264 return false;
1265 }
1266 if (AlwaysActAsServerClassMachine) {
1267 return true;
1268 }
1269 // Then actually look at the machine
1270 bool result = false;
1271 const unsigned int server_processors = 2;
1272 const julong server_memory = 2UL * G;
1273 // We seem not to get our full complement of memory.
1274 // We allow some part (1/8?) of the memory to be "missing",
1275 // based on the sizes of DIMMs, and maybe graphics cards.
1276 const julong missing_memory = 256UL * M;
1278 /* Is this a server class machine? */
1279 if ((os::active_processor_count() >= (int)server_processors) &&
1280 (os::physical_memory() >= (server_memory - missing_memory))) {
1281 const unsigned int logical_processors =
1282 VM_Version::logical_processors_per_package();
1283 if (logical_processors > 1) {
1284 const unsigned int physical_packages =
1285 os::active_processor_count() / logical_processors;
1286 if (physical_packages > server_processors) {
1287 result = true;
1288 }
1289 } else {
1290 result = true;
1291 }
1292 }
1293 return result;
1294 }