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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.
35 lines
862 B
C
35 lines
862 B
C
#pragma once
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#include <sys/cdefs.h>
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#include <sys/types.h>
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#define MAP_SHARED 0x01
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#define MAP_PRIVATE 0x02
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#define MAP_FIXED 0x10
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#define MAP_ANONYMOUS 0x20
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#define MAP_ANON MAP_ANONYMOUS
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#define MAP_STACK 0x40
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#define MAP_PURGEABLE 0x80
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#define PROT_READ 0x1
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#define PROT_WRITE 0x2
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#define PROT_EXEC 0x4
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#define PROT_NONE 0x0
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#define MAP_FAILED ((void*)-1)
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#define MADV_SET_VOLATILE 0x100
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#define MADV_SET_NONVOLATILE 0x200
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__BEGIN_DECLS
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void* mmap(void* addr, size_t, int prot, int flags, int fd, off_t);
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void* mmap_with_name(void* addr, size_t, int prot, int flags, int fd, off_t, const char* name);
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int munmap(void*, size_t);
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int mprotect(void*, size_t, int prot);
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int set_mmap_name(void*, size_t, const char*);
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int shm_open(const char* name, int flags, mode_t);
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int shm_unlink(const char* name);
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int madvise(void*, size_t, int advice);
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__END_DECLS
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