iostat：合併的概念到底是什麼

從iostat手冊頁：

rrqm/s
The number of read requests merged per second that were queued to the device.

wrqm/s
The number of write requests merged per second that were queued to the device.

r/s
 The number (after merges) of read requests completed per second for the device.

w/s
 The number (after merges) of write requests completed per second for the device.

merge由於文件沒有提供任何進一步的細節，任何人都可以詳細說明這個概念嗎？

當兩個 i/o 請求可以合併為一個較長的請求時，就會發生合併。例如，對塊1234的寫入隨後對塊1235的寫入可以合併成對長度為2塊的塊1234的單個i/o請求。由於這種情況相當普遍，因此值得將精力放在核心中進行合併，釋放 i/o 請求結構並減少中斷成本。

如果您對有關 i/o 這方面的更詳細統計資訊感興趣，請參閱 pdf btt 使用者指南，該指南是blktrace.

引用自：https://unix.stackexchange.com/questions/462704