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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.
27 lines
825 B
C++
27 lines
825 B
C++
#pragma once
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#include <Kernel/VM/PhysicalAddress.h>
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#include <Kernel/VM/VMObject.h>
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class AnonymousVMObject : public VMObject {
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public:
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virtual ~AnonymousVMObject() override;
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static NonnullRefPtr<AnonymousVMObject> create_with_size(size_t);
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static NonnullRefPtr<AnonymousVMObject> create_for_physical_range(PhysicalAddress, size_t);
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virtual NonnullRefPtr<VMObject> clone() override;
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protected:
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explicit AnonymousVMObject(size_t);
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explicit AnonymousVMObject(const AnonymousVMObject&);
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private:
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AnonymousVMObject(PhysicalAddress, size_t);
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AnonymousVMObject& operator=(const AnonymousVMObject&) = delete;
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AnonymousVMObject& operator=(AnonymousVMObject&&) = delete;
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AnonymousVMObject(AnonymousVMObject&&) = delete;
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virtual bool is_anonymous() const override { return true; }
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};
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