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VM Statistics |
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============= |
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$Id: vm_stats.txt,v 1.2 2003/08/24 20:24:08 tdb Exp $ |
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Data Structures |
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--------------- |
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These two structures can be returned by the VM system calls: |
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typedef struct{ |
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long long total; |
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long long free; |
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long long used; |
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long long cache; |
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}mem_stat_t; |
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total contains the total memory in bytes. |
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free is the total free memory in bytes. |
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used is the total used memory in bytes. |
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cache is the cache used in bytes. |
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nb: Cache is not available on all operating systems (for example, |
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Solaris). Free memory and cache memory can sometimes be linked. |
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|
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typedef struct{ |
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long long total; |
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long long used; |
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long long free; |
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}swap_stat_t; |
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total contains the total swap space in bytes. |
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used is the used swap in bytes. |
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free is the free swap in bytes. |
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Functions |
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--------- |
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mem_stat_t *get_memory_stats(); |
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swap_stat_t *get_swap_stats(); |
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Memory statistics are accessed through the first call. It returns |
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a pointer to a static mem_stat_t. |
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The second call returns swap statistics. It returns a pointer to |
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a static swap_stat_t. |
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On the FreeBSD operating system elevated privileges are required |
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to access the swap statistics. Making the program setgid kmem should |
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be sufficient. Programs running as root will not have this problem. |
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Todo |
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---- |
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|
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Add a function to hold open the file descriptor to the kernel memory |
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structures. Doing this would allow the elevated privileges to be |
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dropped early on. |
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Example |
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------- |
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An example can be found in examples/vm_stats. |
