1 // Copyright 2015 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_HEAP_SCAVENGE_JOB_H_ 6 #define V8_HEAP_SCAVENGE_JOB_H_ 7 8 #include "src/cancelable-task.h" 9 #include "src/heap/gc-tracer.h" 10 11 namespace v8 { 12 namespace internal { 13 14 class Heap; 15 class Isolate; 16 17 18 // This class posts idle tasks and performs scavenges in the idle tasks. 19 class ScavengeJob { 20 public: 21 class IdleTask : public CancelableIdleTask { 22 public: IdleTask(Isolate * isolate,ScavengeJob * job)23 explicit IdleTask(Isolate* isolate, ScavengeJob* job) 24 : CancelableIdleTask(isolate), job_(job) {} 25 // CancelableIdleTask overrides. 26 void RunInternal(double deadline_in_seconds) override; 27 28 private: 29 ScavengeJob* job_; 30 }; 31 ScavengeJob()32 ScavengeJob() 33 : idle_task_pending_(false), 34 idle_task_rescheduled_(false), 35 bytes_allocated_since_the_last_task_(0) {} 36 37 // Posts an idle task if the cumulative bytes allocated since the last 38 // idle task exceed kBytesAllocatedBeforeNextIdleTask. 39 void ScheduleIdleTaskIfNeeded(Heap* heap, int bytes_allocated); 40 41 // Posts an idle task ignoring the bytes allocated, but makes sure 42 // that the new idle task cannot reschedule again. 43 // This prevents infinite rescheduling. 44 void RescheduleIdleTask(Heap* heap); 45 IdleTaskPending()46 bool IdleTaskPending() { return idle_task_pending_; } NotifyIdleTask()47 void NotifyIdleTask() { idle_task_pending_ = false; } IdleTaskRescheduled()48 bool IdleTaskRescheduled() { return idle_task_rescheduled_; } 49 50 static bool ReachedIdleAllocationLimit(size_t scavenge_speed_in_bytes_per_ms, 51 size_t new_space_size, 52 size_t new_space_capacity); 53 54 static bool EnoughIdleTimeForScavenge(double idle_time_ms, 55 size_t scavenge_speed_in_bytes_per_ms, 56 size_t new_space_size); 57 58 // If we haven't recorded any scavenger events yet, we use a conservative 59 // lower bound for the scavenger speed. 60 static const int kInitialScavengeSpeedInBytesPerMs = 256 * KB; 61 // Estimate of the average idle time that an idle task gets. 62 static const int kAverageIdleTimeMs = 5; 63 // The number of bytes to be allocated in new space before the next idle 64 // task is posted. 65 static const size_t kBytesAllocatedBeforeNextIdleTask = 512 * KB; 66 // The minimum size of allocated new space objects to trigger a scavenge. 67 static const size_t kMinAllocationLimit = 512 * KB; 68 // The allocation limit cannot exceed this fraction of the new space capacity. 69 static const double kMaxAllocationLimitAsFractionOfNewSpace; 70 71 private: 72 void ScheduleIdleTask(Heap* heap); 73 bool idle_task_pending_; 74 bool idle_task_rescheduled_; 75 int bytes_allocated_since_the_last_task_; 76 }; 77 } // namespace internal 78 } // namespace v8 79 80 #endif // V8_HEAP_SCAVENGE_JOB_H_ 81