Re: Which kernel is the best for a small linux system?

[Pantelis Antoniou <pantelis@embeddedalley.com>]

On Monday 13 March 2006 20:27, Sam Ravnborg wrote:
> On Mon, Mar 13, 2006 at 09:17:47AM +0100, Arjan van de Ven wrote:
> > On Sun, 2006-03-12 at 21:40 -0300, j4K3xBl4sT3r wrote:
> > > Hello all,
> > > 
> > > I've been seeing many Linux versions, with many features, some of them
> > > just for the newest branches (2.4.x and 2.6.x), I would like to know
> > > for which kind of system each kernel is recommended. On the distros
> > > that we see inside the Net there is the 2.4.x series, normally I
> > > update to 2.6.x (in case of my Slackware 10.2, even getting problems
> > > with some devices). Is that floppy disks uses only 2.0.x and 2.2.x
> > > Kernels? If applicable, where can I get (detailed) information about
> > > these issues? I'm new on Kernel managing, started doing my own distros
> > > at less than one month and would like to know it.
> > 
> > regardless of the size issue; you should really not start any new
> > projects based on 2.4 kernels; they are in deep deep maintenance mode
> > for now, but it's unclear how long they will be (I suppose as long as
> > people keep sending patches), especially complex security issues should
> > worry people ;)
> > 
> > 2.6 is actively maintained and will be for quite some time :)
> 
> 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;
> # the available RAM size for applications is 700kB smaller
> # Slow to boot: 2.6 takes 5...15% longer to boot into multi-user mode
> # Slow to run: context switches up to 96% slower, local communication
> # latencies up to 80% slower, file system latencies up to 76% slower,
> # local communication bandwidth less than 50% in some cases.
> 
> I'm merely asked because I have been pointed to this page several times
> and I do nto have numbers for 2.4 versus 2.6.
> 
> Note: denx does support 2.6 now.
> 
> I do not concur and recommend 2.6 but wanted to know if anyone had more
> insight to share.
> 
> 	Sam
> -

Hi there.

Since I've been dealing with those platforms quite a lot, let me have
my $0.02.

Yes 2.6 is larger than 2.4 and with small embedded processors with small
caches & a small number of TLBs that footprint is felt quite a lot.

For the 8xx which shows the biggest performance, later kernels offer 
the CONFIG_PIN_TLB option which help quite a bit.

So for anything new I'd recommend 2.6 anyway, the performance delta
is not so great as this test appears to show. I'd like this test to be performed
again against a newer kernel version if possible.

Pantelis