pgpgin|pgpgout|pswpin|pswpout意義與差別

引用來自: http://ssms.cs2c.com.cn/otrs/pc.pl?Action=PublicFAQZoom;ItemID=11741

文章主要意思是:

1. page in/out操做指把塊設備中的頁讀入內存或把內存中的頁寫入塊設備

When ever program or data needs to be accessed and is read in from its permanent location on disk, this is called a page in request.
When ever program or data needs to be saved and is written to a permanent location on disk, this is called a page out request.

2. page in/out中的頁指disk sector,大小爲512字節,而不是虛擬內存中的4k大小的頁

The kernel tracks each disk page (512b) read in within the pgpgin (pages paged in) counter

3. pgpgin/pgpgout是指主存(內存)與塊設備(硬盤)之間的page in/out的頁數.

these counters are related to virtual memory "paging" only in the fact that they are doing disk io to load a memory page with data from disk or write the data from a memory page back to disk

4. pswpin/pswpout是指虛擬內存中,從塊設備swap區中讀入/讀出的頁數.所以是被包含在pgpgin/pgpgout中的.

 pages swapped in or out are also counted within pages paged in or out respectively since swap io is still ultimately block device based.