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[Mammoth] Merge freed slices in buddy allocator.

This commit is contained in:
Drew Galbraith 2023-11-24 14:10:55 -08:00
parent 2a3d384336
commit 8e4cd1562f
1 changed files with 29 additions and 5 deletions
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34
lib/mammoth/util/new.cpp
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@ -31,6 +31,11 @@ struct BuddySlot {
uint64_t size;
};
BuddySlot* GetBuddy(BuddySlot* slot) {
return reinterpret_cast<BuddySlot*>(reinterpret_cast<uint64_t>(slot) ^
slot->size);
}
uint64_t NeededSize(uint64_t size) {
uint64_t needed = size + sizeof(BuddySlot);
// Start at 32 because sizeof(BuddySlot) is already 24;
@ -91,11 +96,29 @@ class BuddyAllocator {
}
void Free(void* ptr) {
check(ZMutexLock(mutex_cap_));
BuddySlot* slot = ((BuddySlot*)ptr) - 1;
// TODO: Merge.
free_front_->prev = slot;
if (slot->next || slot->prev) {
crash("Double free", glcr::INTERNAL);
}
BuddySlot* buddy = GetBuddy(slot);
while ((slot->size < 0x2000) && (buddy->next || buddy->prev) &&
(buddy->size == slot->size)) {
// Buddy is free! Merge!.
Remove(buddy);
if (buddy < slot) {
slot = buddy;
}
slot->size *= 2;
buddy = GetBuddy(slot);
}
if (free_front_) {
free_front_->prev = slot;
}
slot->next = free_front_;
free_front_ = slot;
check(ZMutexRelease(mutex_cap_));
}
private:
@ -103,11 +126,13 @@ class BuddyAllocator {
z_cap_t mutex_cap_ = 0;
void AddPage() {
dbgln("PAGE");
uint64_t vaddr = PageAllocator::AllocatePagePair();
BuddySlot* slot = reinterpret_cast<BuddySlot*>(vaddr);
slot->prev = nullptr;
slot->next = free_front_;
if (free_front_) {
free_front_->prev = slot;
}
free_front_ = slot;
slot->size = 0x2000;
}
@ -118,8 +143,7 @@ class BuddyAllocator {
}
slot->size /= 2;
BuddySlot* new_slot = reinterpret_cast<BuddySlot*>(
reinterpret_cast<uint64_t>(slot) ^ slot->size);
BuddySlot* new_slot = GetBuddy(slot);
new_slot->size = slot->size;
new_slot->next = slot->next;
new_slot->prev = slot;