1 /*
2 * Copyright (c) 2017, Google 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 #ifndef SHARE_VM_RUNTIME_HEAPMONITORING_HPP
26 #define SHARE_VM_RUNTIME_HEAPMONITORING_HPP
27
28 #include "gc/shared/referenceProcessor.hpp"
29 #include "runtime/sharedRuntime.hpp"
30
31 // Support class for sampling heap allocations across the VM.
32 class HeapMonitoring : AllStatic {
33 private:
34 // Cheap random number generator
35 static uint64_t _rnd;
36 static bool _initialized;
37 static jint _monitoring_rate;
38 static bool _enabled;
39
40 // Statics for the fast log
41 static const int _fast_log_num_bits = 10;
42 static const int _fast_log_mask = (1 << _fast_log_num_bits) - 1;
43 static double _log_table[1<<_fast_log_num_bits]; // Constant
44
45 static void pick_next_sample(JavaThread *t);
46
47 // Returns the next prng value.
48 // pRNG is: aX+b mod c with a = 0x5DEECE66D, b = 0xB, c = 1<<48
49 // This is the lrand64 generator.
50 static inline uint64_t next_random(uint64_t rnd) {
51 const uint64_t prng_mult = 0x5DEECE66DLL;
52 const uint64_t prng_add = 0xB;
53 const uint64_t prng_mod_power = 48;
54 const uint64_t prng_mod_mask =
55 ~((~static_cast<uint64_t>(0)) << prng_mod_power);
56 return (prng_mult * rnd + prng_add) & prng_mod_mask;
57 }
58
59 static inline double fast_log2(const double & d) {
60 assert(d>0, "bad value passed to assert");
61 uint64_t x = 0;
62 memcpy(&x, &d, sizeof(uint64_t));
63 const uint32_t x_high = x >> 32;
64 const uint32_t y = x_high >> (20 - _fast_log_num_bits) & _fast_log_mask;
65 const int32_t exponent = ((x_high >> 20) & 0x7FF) - 1023;
66 return exponent + _log_table[y];
67 }
68
69 public:
70 static void pick_next_sample(size_t *ptr);
71
72 static void get_live_traces(jvmtiStackTraces* stack_traces);
73 static void get_garbage_traces(jvmtiStackTraces* stack_traces);
74 static void get_frequent_garbage_traces(jvmtiStackTraces* stack_traces);
75 static void release_traces(jvmtiStackTraces *trace_info);
76 static void initialize_profiling(jint monitoring_rate, jint max_storage);
77 static void stop_profiling();
78 static bool initialized();
79 static bool *initialized_address();
80
81 // Called when o is allocated, called by interpreter and C1.
82 static void object_alloc_unsized(oopDesc* o);
83 static void object_alloc(oopDesc* o, intx byte_size);
84
85 // Called when o is allocated from C2 directly,
86 // we know the thread, and we have done the sampling.
87 static void object_alloc_do_sample(Thread *t, oopDesc *o, intx size_in_bytes);
88
89 // Called to clean up oops that have been saved by our sampling function,
90 // but which no longer have other references in the heap.
91 static void weak_oops_do(AbstractRefProcTaskExecutor *task_executor,
92 BoolObjectClosure* is_alive,
93 OopClosure *f,
94 VoidClosure *complete_gc);
95 static void weak_oops_do(OopClosure* oop_closure) {
96 weak_oops_do(NULL, NULL, oop_closure, NULL);
97 }
98
99 static bool enabled() {
100 return _enabled;
101 }
102 };
103
104 #endif // SHARE_VM_RUNTIME_HEAPMONITORING_HPP