I am a newbie in Write Combine subject. I am measuring a burst IO write performance via mmap on 64 bit Linux and try to understand the WC issue on the IO memory write. I have several basic questions about WC use for this purpose.
The following is my example test setup for a burst write with Write Combine mode enabled:
1. The device driver set IO memory region using ioremap_wc (MTRR). This IO memory is the non prefetchable region. The PAT can be set with write combine or non cached flag.