Re: mmap operation

["Stephen C. Tweedie" <sct@redhat.com>]

Hi,

On Mon, 10 May 1999 18:02:10 +0200 (MET DST), Gilles Pokam
<pokam@cs.tu-berlin.de> said:

> I have implemented a module for buffer management in the 2.0.34 linux
> kernel.  Now i'm using the write and read method for transfering data
> between the kernel and user space. I have noticed that the overhead of
> these 2 operations are quite big, because each time a system call is
> invoked. So i decided to improve my module by implementing the mmap
> operation. The mmap operation works well when mapping only one page
> size. But above this size, for example with an order of at least 1,
> the later operation fails to work! I have noticed that above 4096 (one
> page) bytes the zero page is mapped instead!  Could someone help mee
> solve this problem ? (i use the nopage operation in my mmap method and
> cluster of 16 pages).

The entire VM works by mapping single pages.  It would be a large task
to change this.

--Stephen
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