| 摘要 |
A sampling tool, running on a computer system, sends I/O operations of two different sizes to a storage device, such as a disc drive. These are for a large transfer size, such as 128k bytes and for a small transfer size, such as 4k bytes. The same number of small transfers is sent as large transfers. It measures the total time for the small transfers and the total time for the large transfers. The difference between these is then divided by the number of transfers, multiplied by the size of the small transfer and divided by the difference between the transfer sizes. This result is then multiplied by the number of transfers, subtracted from the total time for large reads and divided by the number of transfers to give the overhead of the I/O operations. The operations may be read operations or they may be write operations.
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