119 SATBMarkQueueSet::~SATBMarkQueueSet() {
120 abandon_completed_buffers();
121 }
122
123 // _count_and_process_flag has flag in least significant bit, count in
124 // remaining bits. _process_completed_buffers_threshold is scaled
125 // accordingly, with the lsbit set, so a _count_and_process_flag value
126 // is directly comparable with the recorded threshold value. The
127 // process flag is set whenever the count exceeds the threshold, and
128 // remains set until the count is reduced to zero.
129
130 // Increment count. If count > threshold, set flag, else maintain flag.
131 static void increment_count(volatile size_t* cfptr, size_t threshold) {
132 size_t old;
133 size_t value = Atomic::load(cfptr);
134 do {
135 old = value;
136 value += 2;
137 assert(value > old, "overflow");
138 if (value > threshold) value |= 1;
139 value = Atomic::cmpxchg(value, cfptr, old);
140 } while (value != old);
141 }
142
143 // Decrement count. If count == 0, clear flag, else maintain flag.
144 static void decrement_count(volatile size_t* cfptr) {
145 size_t old;
146 size_t value = Atomic::load(cfptr);
147 do {
148 assert((value >> 1) != 0, "underflow");
149 old = value;
150 value -= 2;
151 if (value <= 1) value = 0;
152 value = Atomic::cmpxchg(value, cfptr, old);
153 } while (value != old);
154 }
155
156 void SATBMarkQueueSet::set_process_completed_buffers_threshold(size_t value) {
157 // Scale requested threshold to align with count field. If scaling
158 // overflows, just use max value. Set process flag field to make
159 // comparison in increment_count exact.
160 size_t scaled_value = value << 1;
161 if ((scaled_value >> 1) != value) {
162 scaled_value = SIZE_MAX;
163 }
164 _process_completed_buffers_threshold = scaled_value | 1;
165 }
166
167 void SATBMarkQueueSet::set_buffer_enqueue_threshold_percentage(uint value) {
168 // Minimum threshold of 1 ensures enqueuing of completely full buffers.
169 size_t size = buffer_size();
170 size_t enqueue_qty = (size * value) / 100;
171 _buffer_enqueue_threshold = MAX2(size - enqueue_qty, (size_t)1);
172 }
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119 SATBMarkQueueSet::~SATBMarkQueueSet() {
120 abandon_completed_buffers();
121 }
122
123 // _count_and_process_flag has flag in least significant bit, count in
124 // remaining bits. _process_completed_buffers_threshold is scaled
125 // accordingly, with the lsbit set, so a _count_and_process_flag value
126 // is directly comparable with the recorded threshold value. The
127 // process flag is set whenever the count exceeds the threshold, and
128 // remains set until the count is reduced to zero.
129
130 // Increment count. If count > threshold, set flag, else maintain flag.
131 static void increment_count(volatile size_t* cfptr, size_t threshold) {
132 size_t old;
133 size_t value = Atomic::load(cfptr);
134 do {
135 old = value;
136 value += 2;
137 assert(value > old, "overflow");
138 if (value > threshold) value |= 1;
139 value = Atomic::cmpxchg(cfptr, old, value);
140 } while (value != old);
141 }
142
143 // Decrement count. If count == 0, clear flag, else maintain flag.
144 static void decrement_count(volatile size_t* cfptr) {
145 size_t old;
146 size_t value = Atomic::load(cfptr);
147 do {
148 assert((value >> 1) != 0, "underflow");
149 old = value;
150 value -= 2;
151 if (value <= 1) value = 0;
152 value = Atomic::cmpxchg(cfptr, old, value);
153 } while (value != old);
154 }
155
156 void SATBMarkQueueSet::set_process_completed_buffers_threshold(size_t value) {
157 // Scale requested threshold to align with count field. If scaling
158 // overflows, just use max value. Set process flag field to make
159 // comparison in increment_count exact.
160 size_t scaled_value = value << 1;
161 if ((scaled_value >> 1) != value) {
162 scaled_value = SIZE_MAX;
163 }
164 _process_completed_buffers_threshold = scaled_value | 1;
165 }
166
167 void SATBMarkQueueSet::set_buffer_enqueue_threshold_percentage(uint value) {
168 // Minimum threshold of 1 ensures enqueuing of completely full buffers.
169 size_t size = buffer_size();
170 size_t enqueue_qty = (size * value) / 100;
171 _buffer_enqueue_threshold = MAX2(size - enqueue_qty, (size_t)1);
172 }
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