On Sun, Nov 23, 2008 at 2:23 AM, Rik van Riel <riel@xxxxxxxxxxx> wrote:
According to your explanation, the flow is physical file(on disk)-->Page Cache(on memory, but in kernel space)-->Process Memory(on memory, but in user space). Is it? I am not sure....
But what is the difference? Why linux do it?
Peter Teoh wrote:No, it does not maintain a copy.
when a process mmap() a section of a file into its own process memory,
the process memory will maintain a copy of the data of that section of
the file.
It mmaps the page cache pages into its own address space.
According to your explanation, the flow is physical file(on disk)-->Page Cache(on memory, but in kernel space)-->Process Memory(on memory, but in user space). Is it? I am not sure....
No, there is no such double buffering.
so...does there exists duplicated buffering? (one in kernel -
pagecache, and one in userspace - for mmap() content of the file in
process memory)
But what is the difference? Why linux do it?
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