mirror of
https://github.com/RGBCube/serenity
synced 2025-05-31 10:38:11 +00:00
ba87571366
The previous allocator was very naive and kept the state of all pages in one big bitmap. When allocating, we had to scan through the bitmap until we found an unset bit. This patch introduces a new binary buddy allocator that manages the physical memory pages. Each PhysicalRegion is divided into zones (PhysicalZone) of 16MB each. Any extra pages at the end of physical RAM that don't fit into a 16MB zone are turned into 15 or fewer 1MB zones. Each zone starts out with one full-sized block, which is then recursively subdivided into halves upon allocation, until a block of the request size can be returned. There are more opportunities for improvement here: the way zone objects are allocated and stored is non-optimal. Same goes for the allocation of buddy block state bitmaps.
43 lines
1.2 KiB
C++
43 lines
1.2 KiB
C++
/*
|
|
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
|
|
*
|
|
* SPDX-License-Identifier: BSD-2-Clause
|
|
*/
|
|
|
|
#include <Kernel/Heap/kmalloc.h>
|
|
#include <Kernel/VM/MemoryManager.h>
|
|
#include <Kernel/VM/PhysicalPage.h>
|
|
|
|
namespace Kernel {
|
|
|
|
NonnullRefPtr<PhysicalPage> PhysicalPage::create(PhysicalAddress paddr, bool may_return_to_freelist)
|
|
{
|
|
auto& physical_page_entry = MM.get_physical_page_entry(paddr);
|
|
return adopt_ref(*new (&physical_page_entry.allocated.physical_page) PhysicalPage(may_return_to_freelist));
|
|
}
|
|
|
|
PhysicalPage::PhysicalPage(bool may_return_to_freelist)
|
|
: m_may_return_to_freelist(may_return_to_freelist)
|
|
{
|
|
}
|
|
|
|
PhysicalAddress PhysicalPage::paddr() const
|
|
{
|
|
return MM.get_physical_address(*this);
|
|
}
|
|
|
|
void PhysicalPage::free_this()
|
|
{
|
|
auto paddr = MM.get_physical_address(*this);
|
|
if (m_may_return_to_freelist) {
|
|
auto& this_as_freelist_entry = MM.get_physical_page_entry(paddr).freelist;
|
|
this->~PhysicalPage(); // delete in place
|
|
this_as_freelist_entry.next_index = -1;
|
|
this_as_freelist_entry.prev_index = -1;
|
|
MM.deallocate_physical_page(paddr);
|
|
} else {
|
|
this->~PhysicalPage(); // delete in place
|
|
}
|
|
}
|
|
|
|
}
|