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Date: Mon, 13 Mar 2006 20:08:27 +0100
From: Diego Calleja <diegocg@gmail.com>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: arjan@infradead.org, jakexblaster@gmail.com, linux-kernel@vger.kernel.org
Subject: Re: Which kernel is the best for a small linux system?
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El Mon, 13 Mar 2006 19:27:25 +0100,
Sam Ravnborg <sam@ravnborg.org> escribió:

> Any comments on this:
> http://www.denx.de/wiki/Know/Linux24vs26
> 
> On another denx.de page I found this summary (so you do not have to
> visit the page):
> # slow to build: 2.6 takes 30...40% longer to compile
> # Big memory footprint in flash: the 2.6 compressed kernel image is
> # 30...40% bigger
> # Big memory footprint in RAM: the 2.6 kernel needs 30...40% more RAM;

In one of those analysis (2.6 sandpoint kernel) they didn't disable
CONFIG_KALLSYMS (they disabled it on the tqm860l though), that makes the
kernel way too big and should be disabled by embedded systems, I don't
understand. That one at least should be fixed, 2.4 didn't even feature
kallsyms.

Also, they claim that context switches are "on average 55% slower (range:
10...94%)", which may be very well a ppc-only bug (in x86 at least
system calls got much faster). And syscalls being much slower is why most
of the other microbenchmarks look so bad.