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Diskio Statistics |
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All diskio statistics return a diskio_stat_t structure. |
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typedef struct{ |
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char *disk_name; |
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long long read_bytes; |
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long long write_bytes; |
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time_t systime; |
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}diskio_stat_t; |
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disk_name is the name know to the OS. E.g. hda on linux. |
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read_bytes is the number of bytes that disk has read. |
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write_bytes is the number of bytes that disk has written. |
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sysname is time_t covering the time the amount of data in rx/tx was |
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generated. |
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diskio_stat_t *get_diskio_stats(int *entries); |
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diskio_stat_t *get_diskio_stats_diff(int *entries); |
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Both calls take a pointer to an int, "entries". This is filled with the number |
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of disks the machine has. You need to know this to know how many diskio_stat_t |
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have been returned. |
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get_diskio_stats returns the disk io stored in the kernel. E.g. |
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since bootup as long as the way it is stored in the kernel can store a large |
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enough number. Solaris 7 can not, it only stores it in a 32bit int, so it |
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can only store upto 4gb before it will wrap around. Solaris 8 upwards stores |
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it in a 64bit int and so is a very large number :) |
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get_diskio_stats_diff is the same as get_diskio_stats except it will |
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return the difference since the last call. So, for instance a call to |
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get_diskio_stats_diff is made, and called again 5 seconds later. Over that |
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time, 2000 bytes of traffic was written and 10000 bytes read. write_bytes will |
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store 2000 bytes, read_bytes will store 10000 and systime will store 5. This |
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function copes with wrap arounds by the O/S so should be seemless to use. |
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Bugs: |
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get_diskio_stats_diff on very first call will return the same as |
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get_diskio_stats. After first call it will always return the difference. |
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On machines that hold only 32bits of information, if the call is made 2x |
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wrap around (eg sol7 9gb has been transferred, and it wraps at 4gb) it will |
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return incorrect results (case above, it would say 5gb transferred). |
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Very basic example in examples/disk_traffic.c |
