Date: Thu, 10 Nov 2011 19:16:27 +0100 From: Ed Schouten <ed@80386.nl> To: Garrett Cooper <yanegomi@gmail.com> Cc: arch@freebsd.org Subject: Re: The strangeness called `sbin' Message-ID: <20111110181627.GK2164@hoeg.nl> In-Reply-To: <CAGH67wSw-aSbXdskApWdAD59TwDHW7QeYGmY4vTZaPWMubDb5w@mail.gmail.com> References: <20111110123919.GF2164@hoeg.nl> <CAGE5yCr3BzWzwOAqo7wifgUTRC%2BG=2o4bDmk9H-%2BCxr=zJqYmw@mail.gmail.com> <20111110171605.GI2164@hoeg.nl> <CAGE5yCqMcHwAhXKbyEH6vUR=N14tCjkgX=RMJTdq-po92GcOMQ@mail.gmail.com> <20111110174722.GJ2164@hoeg.nl> <CAGH67wSw-aSbXdskApWdAD59TwDHW7QeYGmY4vTZaPWMubDb5w@mail.gmail.com>
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* Garrett Cooper <yanegomi@gmail.com>, 20111110 19:12:
> On Thu, Nov 10, 2011 at 9:47 AM, Ed Schouten <ed@80386.nl> wrote:
> > * Peter Wemm <peter@wemm.org>, 20111110 18:33:
> >> Having /sbin in $PATH where /sbin is a symlink to /bin would be worse
> >> than having no /sbin at all, from a perspective of rootvnode lock
> >> lifetime. If you can figure out how to get people to remove /sbin and
> >> /usr/sbin from their paths after the symlink changes then it becomes a
> >> moot point. But heck, I still have /usr/X11R6 in mine... :(
> >
> > On the other hand, if people used to have /sbin in their path and *do*
> > remove it properly after the upgrade, they should in theory see a
> > performance improvement, right?
>
> Doesn't the negative directory cache (namei, etc) mitigate this?
Peter is also talking about the fact that if you have a PATH like
/bin:/sbin:... and /sbin is a symbolic link to /bin, you end up doing
this:
execve("/bin/YOURAPP", ...) -> fails
execve("/sbin/YOURAPP", ...) -> fails
...
execve("/some/other/directory/YOURAPP", ...) -> success
The first two system calls together are expected to be slightly slower
than they used to be, because both these directories have now grown.
--
Ed Schouten <ed@80386.nl>
WWW: http://80386.nl/
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