Re: A Comment from User Space

From: jmjonesat_private
Date: Wed Apr 25 2001 - 05:40:54 PDT

  • Next message: jmjonesat_private: "Re: A Comment from User Space"

    David Wagner wrote:
    >
    > Steve Beattie  wrote:
    > >It seems unlikely to me that using /proc or a private fs can NOT be
    > >slower.
    >
    > The important question is not whether it is slower.  The real question
    > is whether it is too slow.  Those are *very* different questions.
    
    Interesting results of my "semi-scientific" relative performance tests
    of a proc system read of uid_t size compared to getuid():
    
    2.0.x kernels: (PROC:GETUID)
    
    1.2:1  on MIPS
      1:1  on i586
    
    2.2.x kernels: (PROC:GETUID)
    
      6:1  on i686
    
    Not sure why that should be, except it appears that 10million
    reads of /proc fs data take approximately the same time for 
    all the systems (24000ms) (bogomips ranging from 40 to 1000)
    and getuid is MUCH FASTER on the 2.2 kernel with 1000 bogomips.
    (caching?)
    
    All systems were at >0.10 load (and similarly loaded) during the
    test.
    
    Ergo, my simple test (performed from userspace as root) suggests
    the impact is "highly variable", but COULD be relatively insignificant
    if, as Mr. Wagner suggests, it's used sparingly.
    
    For What It's Worth,
    J. Melvin Jones
    
     
    |>------------------------------------------------------
    ||  J. MELVIN JONES            jmjonesat_private 
    |>------------------------------------------------------
    ||  Microcomputer Systems Consultant  
    ||  Software Developer
    ||  Web Site Design, Hosting, and Administration
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    ||  http://www.jmjones.com/
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