Re: Building the kernel on an SMP box?

["Jesper Juhl" <jesper.juhl@gmail.com>]

On 27/07/06, Brian D. McGrew <brian@visionpro.com> wrote:
> Good morning all!
>
> Currently I'm building my kernels on a Dell PE 1800 3.0GHz.  My dilemma
> is that I build and rebuild the kernel about twenty times a day and even
> though it only takes about 20 minutes, that's rapidly becoming too slow!
> Today it's the 2.6.17 kernel on FC5 that I'm building with.
>
> I see all these blurbs out there about someone being able to build a
> complete kernel in under a minute or running an SMP build across
> multiple CPUS and/or multiple machines.
>
> So, to ask the group that should know the best ... What would be a
> reasonable configuration to get my builds down under five minutes or so?

My box builds my ordinary .config (attached) in under 5min :

$ time make -j3
real    3m58.047s
user    4m54.574s
sys     1m24.202s

Here are some more numbers for you to compare to your box :

allnoconfig :

$ make clean
$ make allnoconfig
$ time make -j3
real    0m54.544s
user    1m2.113s
sys     0m20.781s


allmodconfig :

$ make clean
$ make allmodconfig
$ time make -j3
real    28m49.748s
user    35m3.212s
sys     10m43.633s


This box uses a Athlon64 X2 4400+ CPU, has 2GB RAM and a single
Ultra160 SCSI disk.
It's currently running an i386 kernel, not x86_64, so it's probably
not performing to it's full potential atm.


> And then to go to the extreme, what kind of horsepower should I be
> looking for if I want get the build times down to say a minute or so???
Make sure you have a fast disk and adequate amounts of RAM so you
don't end up swapping, then add more CPU's.
A dual-core box is not too expensive these days and an additional core
really speeds things up. If you have the money for it, then a box with
two dual-core CPU's is ofcourse even better.
If you have several machines, then you can use distcc
(http://distcc.samba.org/) to distribute the build across the boxes -
that's an easy way to speed things up if you have a bunch of older
computers lying around.


--
Jesper Juhl <jesper.juhl@gmail.com>
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