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Date:      Tue, 3 Jun 2003 10:59:37 +0100
From:      Paul Robinson <paul@iconoplex.co.uk>
To:        Martin Blapp <mb@imp.ch>
Cc:        Andrew Gallatin <gallatin@cs.duke.edu>
Subject:   Re: Making a dynamically-linked root
Message-ID:  <20030603095937.GC92839@iconoplex.co.uk>
In-Reply-To: <20030603113927.I71313@cvs.imp.ch>
References:  <20030603113927.I71313@cvs.imp.ch>

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On Tue, Jun 03, 2003 at 11:43:20AM +0200, Martin Blapp wrote:

> This is during startup. Webservers and all other applications are
> still dynamically linked as before. No speed loss there.

Two points (and I apologise for coming in a little late):

1. There is a speed loss in a dynamic environment. It's marginal, and it
depends on the apps you need bootstrapping, but it's there. If you require
me to benchmark, give me until the weekend.

2. The real issue with dynamic linking is not performance - it's mounting. 
If I *need* an application up for the box to be useful to me (e.g., lights 
out server, other continent, I need sshd up) and it can't bootstrap because 
/usr/local isn't available due to an fsck problem, I'm in a bit of trouble. 
This is why root's shell should alwayd be statically linked, always in /bin 
and why for years when su'ing the first command I would type would be 
/usr/local/bin/tcsh rather than have tcsh as my default root shell.

As an appendix, I could point out the security problems a dynamically linked
environment *could* present as well, but normally people aren't that stupid 
in the administration of their machines.

Everything in base required to get a box up to the point of a login prompt, 
and preferably a remote login, should be statically linked IMHO.
 
> There are other places to speed up the startup ...

This is starting to sound like the Microsoft "well, we haven't got it to 
stop crashing, but the reboots only take 10 seconds now" argument for Win2K. 
Nobody cares about the speed of startup except laptop users (of which I am 
one), but rather the security and sanity of startup. Sure, it would be nice 
if my laptop booted up -STABLE 8.6 seconds quicker than before, but to be 
honest, I'm just glad it works and I can be sure it will definitely come up 
no matter what, and no matter how long it will take, and if it won't I have 
a statically linked shell to help me sort it out.
 
> For example, with my dhclient patch you can speedup the startup
> time by 5 seconds if you use dhcp ...

That's great again for laptop users, but when you're an admin with a few 
hundred boxes on the other side of the country, this interesting performance 
increase doesn't seem quite so funky...

-- 
Paul Robinson



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