[Prev][Next][Index][Thread]

# [sting@linguist.dartmouth.edu: Re: Server Improvement]

- Date: Thu, 27 Mar 1997 12:32:15 -0600
- From:

    ------- Start of forwarded message -------
    Return-Path: nop@ccs.neu.edu
    X-Disclaimer: This message was received from outside Dartmouth's BlitzMail system.
    In-Reply-To: <Pine.SUN.3.91.970318112846.9663C-100000@t9>
    Mime-Version: 1.0
    Content-Type: text/plain; charset="us-ascii"
    Date: Tue, 18 Mar 1997 05:17:36 PST
    To: moo-cows@parc.xerox.com
    From: "\"Michael J. Fromberger\"." <sting@linguist.dartmouth.edu>
    Subject: Re: Server Improvement
    Sender: MOO-Cows-Errors@parc.xerox.com
    Precedence: bulk
    Resent-From: clue-cows <nop@nop.com>
    Errors-To: clue-cows <nop@nop.com>
    Resent-From: clue-cows <nop@nop.com>
    Errors-To: clue-cows <nop@nop.com>

    At 03.38 -0800 3/18/97, chris wrote:
    >Switch statements in C are meant to be very efficient (although that
    >might change from compiler to compiler)
    [...]
    >
    >What I would like to put up for discussion is the merits of using a array
    >of pointers to functions instead of a switch statement, as this would
    >eleminate the need to perform a integer search.
    [...]
    >Do people think that this would result in a significant performance boost?
    >

    Since, as you say, the implementation of this can and does vary from
    cpmpiler to compiler, the boost you'd get for doing this will be hard to
    estimate.  My guess is that the only way to get any real data would be to
    build a copy of the server with profiling code in, and get some figures for
    just how much time the instruction decode/dispatch really takes.  Armed
    with that, it would be much easier to simulate some test cases done off a
    dispatch vector and see what the magnitude of the improvement will be.

    Broadly speaking, if we assume that the "standard" implementation is likely
    to involve search of some kind (I have no idea if this is the case or not),
    you'd expect to see some kind of performance boost for this.  However,
    cache policies and size, register allocation, and memory architecture will
    contribute heavily to the success of this venture.

    Overall, it's not at all a bad idea, IMHO -- but it's impossible to say
    what the exact effect will be without some testing.

    Cheers,
    - -M

     +--------+
     |:::::://|  Michael J. Fromberger         Tel 617 * 276 * 8885
     |{\:::// |  Software Toolsmith            FAX 617 * 276 * 8878
     |{\\://  |
     |::\//   | <mailto:michaelf@vgi.com>     <http://www.vgi.com/>
     +--------+ +------------------------------------------------------+
     VideoGuide          209 Burlington Road, Bedford, MA  01730
    ------- End of forwarded message -------

- Prev: [sting@linguist.dartmouth.edu: Re: Server Improvement]
- Next: [thomas@xs4all.nl: Re: Fileio and 1.8.0p6]
- Index: MOO-cows
- Thread: MOO-cows

Home | Subject Index | Thread Index