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 {
33 private:
34 // Cheap random number generator
35 static uint64_t _rnd;
36 static bool _initialized;
37 static jint _monitoring_rate;
38
39 // Statics for the fast log
40 static const int kFastlogNumBits = 10;
41 static const int kFastlogMask = (1 << kFastlogNumBits) - 1;
42 static double _log_table[1<<kFastlogNumBits]; // Constant
43
44 static void pick_next_sample(JavaThread *t);
45
46 // Returns the next prng value.
47 // pRNG is: aX+b mod c with a = 0x5DEECE66D, b = 0xB, c = 1<<48
48 // This is the lrand64 generator.
49 static inline uint64_t next_random(uint64_t rnd) {
50 const uint64_t prng_mult = 0x5DEECE66DLL;
51 const uint64_t prng_add = 0xB;
52 const uint64_t prng_mod_power = 48;
53 const uint64_t prng_mod_mask =
54 ~((~static_cast<uint64_t>(0)) << prng_mod_power);
55 return (prng_mult * rnd + prng_add) & prng_mod_mask;
56 }
57
58 // Adapted from //util/math/fastmath.[h|cc] by Noam Shazeer
59 // This mimics the VeryFastLog2 code in those files
60 static inline double fast_log2(const double & d) {
61 assert(d>0, "bad value passed to assert");
62 uint64_t x = 0;
63 memcpy(&x, &d, sizeof(uint64_t));
64 const uint32_t x_high = x >> 32;
65 const uint32_t y = x_high >> (20 - kFastlogNumBits) & kFastlogMask;
66 const int32_t exponent = ((x_high >> 20) & 0x7FF) - 1023;
67 return exponent + _log_table[y];
68 }
69
70 public:
71 static void get_live_traces(jvmtiStackTraces* stack_traces);
72 static void get_garbage_traces(jvmtiStackTraces* stack_traces);
73 static void get_frequent_garbage_traces(jvmtiStackTraces* stack_traces);
74 static void release_traces(jvmtiStackTraces *trace_info);
75 static void initialize_profiling(jint monitoring_rate, jint max_storage);
76 static bool initialized();
77 static bool *initialized_address();
78
79 // Called when o is allocated, called by interpreter and C1.
80 static void object_alloc_unsized(oopDesc* o);
81 static void object_alloc(oopDesc* o, intx byte_size);
82
83 // Called when o is allocated from C2 directly,
84 // we know the thread, and we have done the sampling.
85 static void object_alloc_do_sample(Thread *t, oopDesc *o, intx size_in_bytes);
86
87 // Called to clean up oops that have been saved by our sampling function,
88 // but which no longer have other references in the heap.
89 static void do_weak_oops(AbstractRefProcTaskExecutor *task_executor,
90 BoolObjectClosure* is_alive,
91 OopClosure *f,
92 VoidClosure *complete_gc);
93 static void do_weak_oops(OopClosure* oop_closure) {
94 do_weak_oops(NULL, NULL, oop_closure, NULL);
95 }
96 };
97
98 #endif // SHARE_VM_RUNTIME_HEAPMONITORING_HPP