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From: Maxim Sobolev <sobomax@FreeBSD.ORG>
Message-Id: <200102022236.f12Ma7N17166@vic.sabbo.net>
Subject: Re: mdconfig config file (was: cvs commit: src/sys/i386/conf GENERI C)
To: dillon@earth.backplane.com (Matt Dillon)
Date: Sat, 3 Feb 2001 00:36:07 +0200 (EET)
Cc: sobomax@FreeBSD.ORG (Maxim Sobolev),
	dima@unixfreak.org (Dima Dorfman), mi@aldan.algebra.com,
	deischen@FreeBSD.ORG, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG
In-Reply-To: <200102022218.f12MIV700601@earth.backplane.com> from "Matt Dillon" at Feb 02, 2001 02:18:31 PM
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> 
> 
> :
> :> <snip>
> :> 
> :>     if ((pid = fork()) == 0) {
> :
> :Probably vfork() is better here, no?
> :
> :-Maxim
> 
>     My rule for using vfork() is:  Does it improve performance in
>     a noticeable way?  The answer, at least for mount_*, is no.  If the
>     answer is no, you should simply use a normal fork().
> 
>     fork() under FreeBSD is not all that expensive.  vfork() will be faster,
>     but unless you are fork/exec'ing a few dozen commands a second you will
>     never notice the difference.

Well, I'm using a slightly different rule: Does it really need a full fork()
to work correctly. The answer in this case is obviously no. Therefore vfork()
could (and should IMO) be used instead. While it obviously wouldn't make any
difference from the performance standpoind, but it's better from the
ideological standpoint (for example one can cut'n'paste this handy code into
his own program w/o taking into consideration fork() vs. vfork() issue).

-Maxim


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