Thread (5 messages) 5 messages, 4 authors, 2003-09-08

Re: Differences between VM structs

From: William Lee Irwin III <hidden>
Date: 2003-09-08 18:21:38

On Mon, Sep 08, 2003 at 09:26:59AM -0700, Kirk True wrote:
    1. Regarding non-contiguous memory allocation, what is the need to 
       have *virtually* contiguous but not *physically* contiguous
       pages?
Fragmentation happens.


On Mon, Sep 08, 2003 at 09:26:59AM -0700, Kirk True wrote:
    2. UtLVMM says that vmalloc is only used in the kernel for storing
       swap information - yet it's used by a bunch of drivers which
       are considered part of the kernel; is it just semantics?
No, its usage has probably expanded. Drivers are generally not supposed
to try to use it directly. It's used for things like vmap() too nowadays.


On Mon, Sep 08, 2003 at 09:26:59AM -0700, Kirk True wrote:
    3. Is vmalloc called from user-mode ever?
No function in the kernel can be called directly from usermode.


On Mon, Sep 08, 2003 at 09:26:59AM -0700, Kirk True wrote:
    4. Can you state a succint/brief comparison of the difference
       between kmalloc, malloc, and vmalloc with usage examples of each?
No.


On Mon, Sep 08, 2003 at 09:26:59AM -0700, Kirk True wrote:
    5. Anonymous memory is memory that is *not* backed by a file, such
       as the stack or heap space, right? And mmap is called when
       mapping files into memory, right? The why does mmap deal with
       anonymous memory (sorry, I'm totally confused here)?
mmap() needed very few extensions to handle the anonymous case.


-- wli
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