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comparison src/share/vm/runtime/os.cpp @ 61:5a76ab815e34

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6667833: Remove CacheTimeMillis Summary: Remove -XX:+CacheTimeMillis option and associated functionality Reviewed-by: acorn, never
author sbohne
date Wed, 19 Mar 2008 09:58:01 -0400
parents 2a8eb116ebbe
children d1605aabd0a1
comparison
equal deleted inserted replaced
60:8d84e28e68ba 61:5a76ab815e34
31 address os::_polling_page = NULL; 31 address os::_polling_page = NULL;
32 volatile int32_t* os::_mem_serialize_page = NULL; 32 volatile int32_t* os::_mem_serialize_page = NULL;
33 uintptr_t os::_serialize_page_mask = 0; 33 uintptr_t os::_serialize_page_mask = 0;
34 long os::_rand_seed = 1; 34 long os::_rand_seed = 1;
35 int os::_processor_count = 0; 35 int os::_processor_count = 0;
36 volatile jlong os::_global_time = 0;
37 volatile int os::_global_time_lock = 0;
38 bool os::_use_global_time = false;
39 size_t os::_page_sizes[os::page_sizes_max]; 36 size_t os::_page_sizes[os::page_sizes_max];
40 37
41 #ifndef PRODUCT 38 #ifndef PRODUCT
42 int os::num_mallocs = 0; // # of calls to malloc/realloc 39 int os::num_mallocs = 0; // # of calls to malloc/realloc
43 size_t os::alloc_bytes = 0; // # of bytes allocated 40 size_t os::alloc_bytes = 0; // # of bytes allocated
44 int os::num_frees = 0; // # of calls to free 41 int os::num_frees = 0; // # of calls to free
45 #endif 42 #endif
46
47 // Atomic read of a jlong is assured by a seqlock; see update_global_time()
48 jlong os::read_global_time() {
49 #ifdef _LP64
50 return _global_time;
51 #else
52 volatile int lock;
53 volatile jlong current_time;
54 int ctr = 0;
55
56 for (;;) {
57 lock = _global_time_lock;
58
59 // spin while locked
60 while ((lock & 0x1) != 0) {
61 ++ctr;
62 if ((ctr & 0xFFF) == 0) {
63 // Guarantee writer progress. Can't use yield; yield is advisory
64 // and has almost no effect on some platforms. Don't need a state
65 // transition - the park call will return promptly.
66 assert(Thread::current() != NULL, "TLS not initialized");
67 assert(Thread::current()->_ParkEvent != NULL, "sync not initialized");
68 Thread::current()->_ParkEvent->park(1);
69 }
70 lock = _global_time_lock;
71 }
72
73 OrderAccess::loadload();
74 current_time = _global_time;
75 OrderAccess::loadload();
76
77 // ratify seqlock value
78 if (lock == _global_time_lock) {
79 return current_time;
80 }
81 }
82 #endif
83 }
84
85 //
86 // NOTE - Assumes only one writer thread!
87 //
88 // We use a seqlock to guarantee that jlong _global_time is updated
89 // atomically on 32-bit platforms. A locked value is indicated by
90 // the lock variable LSB == 1. Readers will initially read the lock
91 // value, spinning until the LSB == 0. They then speculatively read
92 // the global time value, then re-read the lock value to ensure that
93 // it hasn't changed. If the lock value has changed, the entire read
94 // sequence is retried.
95 //
96 // Writers simply set the LSB = 1 (i.e. increment the variable),
97 // update the global time, then release the lock and bump the version
98 // number (i.e. increment the variable again.) In this case we don't
99 // even need a CAS since we ensure there's only one writer.
100 //
101 void os::update_global_time() {
102 #ifdef _LP64
103 _global_time = timeofday();
104 #else
105 assert((_global_time_lock & 0x1) == 0, "multiple writers?");
106 jlong current_time = timeofday();
107 _global_time_lock++; // lock
108 OrderAccess::storestore();
109 _global_time = current_time;
110 OrderAccess::storestore();
111 _global_time_lock++; // unlock
112 #endif
113 }
114 43
115 // Fill in buffer with current local time as an ISO-8601 string. 44 // Fill in buffer with current local time as an ISO-8601 string.
116 // E.g., yyyy-mm-ddThh:mm:ss-zzzz. 45 // E.g., yyyy-mm-ddThh:mm:ss-zzzz.
117 // Returns buffer, or NULL if it failed. 46 // Returns buffer, or NULL if it failed.
118 // This would mostly be a call to 47 // This would mostly be a call to
136 if (buffer_length < needed_buffer) { 65 if (buffer_length < needed_buffer) {
137 assert(false, "buffer_length too small"); 66 assert(false, "buffer_length too small");
138 return NULL; 67 return NULL;
139 } 68 }
140 // Get the current time 69 // Get the current time
141 jlong milliseconds_since_19700101 = timeofday(); 70 jlong milliseconds_since_19700101 = javaTimeMillis();
142 const int milliseconds_per_microsecond = 1000; 71 const int milliseconds_per_microsecond = 1000;
143 const time_t seconds_since_19700101 = 72 const time_t seconds_since_19700101 =
144 milliseconds_since_19700101 / milliseconds_per_microsecond; 73 milliseconds_since_19700101 / milliseconds_per_microsecond;
145 const int milliseconds_after_second = 74 const int milliseconds_after_second =
146 milliseconds_since_19700101 % milliseconds_per_microsecond; 75 milliseconds_since_19700101 % milliseconds_per_microsecond;