Re: [RFC] Optimization for use-once pages

Mike Castle (dalgoda@ix.netcom.com)
Tue, 24 Jul 2001 11:15:30 -0700


On Tue, Jul 24, 2001 at 02:51:03PM -0300, Rik van Riel wrote:
> Let me give you an example:
>
> - sequential access of a file
> - script reads the file in 80-byte segments
> (parsing some arcane data structure)
> - these segments are accessed in rapid succession
> - each 80-byte segment is accessed ONCE
>
> In this case, even though the data is accessed only
> once, each page is touched PAGE_SIZE/80 times, with
> one 80-byte read() each time.

Of course, such a program is poorly written anyway. That many individual
system calls! At least rewrite to use fread(). ;->

Change the example to using mmap(), and one feels less likely throttle the
programmer.

mrc

-- 
     Mike Castle      dalgoda@ix.netcom.com      www.netcom.com/~dalgoda/
    We are all of us living in the shadow of Manhattan.  -- Watchmen
fatal ("You are in a maze of twisty compiler features, all different"); -- gcc
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