From owner-freebsd-hackers@FreeBSD.ORG  Wed Jul 11 21:14:28 2007
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Date: Wed, 11 Jul 2007 14:14:27 -0700 (PDT)
From: Matthew Dillon <dillon@apollo.backplane.com>
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To: Julian Elischer <julian@elischer.org>
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Cc: freebsd-hackers@freebsd.org
Subject: Re: add closefrom() call
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    We added it basically because doing all the junk described in
    previous postings in this thread in userland is a ridiculously huge
    eyesore that doesn't scale and doesn't make sense when 5 minutes of
    programming nets you a shiny new system call which does it all for you.

    If you are worried about optimizing it (which kinda implies a system
    call anyhow since you aren't doing a context switch for each descriptor),
    worry about optimizing the kernel implementation of the system call
    rather then optimizing the unoptimizable userland that eats 300ns+ per
    descriptor to do the close() instead of the 10ns/descriptor that it
    takes the kernel to do the close().

						-Matt