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dbb644f20c
It's now possible to get purgeable memory by using mmap(MAP_PURGEABLE). Purgeable memory has a "volatile" flag that can be set using madvise(): - madvise(..., MADV_SET_VOLATILE) - madvise(..., MADV_SET_NONVOLATILE) When in the "volatile" state, the kernel may take away the underlying physical memory pages at any time, without notifying the owner. This gives you a guilt discount when caching very large things. :^) Setting a purgeable region to non-volatile will return whether or not the memory has been taken away by the kernel while being volatile. Basically, if madvise(..., MADV_SET_NONVOLATILE) returns 1, that means the memory was purged while volatile, and whatever was in that piece of memory needs to be reconstructed before use.
53 lines
1.4 KiB
C++
53 lines
1.4 KiB
C++
#pragma once
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#include <AK/FixedArray.h>
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#include <AK/InlineLinkedList.h>
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#include <AK/RefCounted.h>
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#include <AK/RefPtr.h>
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#include <AK/Weakable.h>
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#include <Kernel/Lock.h>
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class Inode;
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class PhysicalPage;
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class VMObject : public RefCounted<VMObject>
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, public Weakable<VMObject>
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, public InlineLinkedListNode<VMObject> {
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friend class MemoryManager;
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friend class Region;
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public:
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virtual ~VMObject();
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virtual NonnullRefPtr<VMObject> clone() = 0;
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virtual bool is_anonymous() const { return false; }
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virtual bool is_purgeable() const { return false; }
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virtual bool is_inode() const { return false; }
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size_t page_count() const { return m_physical_pages.size(); }
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const FixedArray<RefPtr<PhysicalPage>>& physical_pages() const { return m_physical_pages; }
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FixedArray<RefPtr<PhysicalPage>>& physical_pages() { return m_physical_pages; }
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size_t size() const { return m_physical_pages.size() * PAGE_SIZE; }
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// For InlineLinkedListNode
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VMObject* m_next { nullptr };
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VMObject* m_prev { nullptr };
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protected:
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explicit VMObject(size_t);
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explicit VMObject(const VMObject&);
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template<typename Callback>
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void for_each_region(Callback);
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FixedArray<RefPtr<PhysicalPage>> m_physical_pages;
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Lock m_paging_lock { "VMObject" };
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private:
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VMObject& operator=(const VMObject&) = delete;
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VMObject& operator=(VMObject&&) = delete;
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VMObject(VMObject&&) = delete;
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};
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