Re: Has anyone used multi- cpu's on debian
--- butch@maestro.com wrote:
with the cost of multiple cpu motherboards going down i
was wondering if anyone has created a super debian system?
allan
ps what apps are you runnning?
--- end of quoted material ---
Yes, I have. 2xPPro 200/256k on a Tyan S1662D, 128M RAM. I pulled the hard
drives from my old 486 and plugged them into the new system - presto! instant
power! I did have a little trouble because I put the two hard drives on
separate busses, so my Linux drive moved from hdb to hdc, but that was a
detail. You do need to recompile the kernel after uncommenting the SMP=1 line
at the top of "Makefile" in /usr/src/linux/ (use make-kpkg for this) and reboot
with the new kernel, and you need to remove all references to "setserial" from
/etc/init.d. Otherwise, no more trouble than installing Debian on a single
processor box, which is to say, easy. The usual caveats with quality hardware
go double with a multiple CPU setup, but that's important for a trouble-free
setup under any circumstances.
One thing I have noticed is that the X server will run on 1 CPU, while your
application will run on the other. This helps everything. Programs which I
know aren't multithreaded still go over 100% CPU usage when the X Server is
involved. For two CPU bound tasks (the RSA datasecurity challenge program is a
prime example), top reports 99.9% CPU usage for one process and 97.9% CPU usage
for the other. I'm not going to complain about that :-). For two memory
intensive programs the efficiency drops quite a bit, but is still faster than a
2 processor Sun Sparc Ultra (also at 200Mhz) with the same program. My
understanding is that Pentium based multi-CPU boards lose even more due to the
shared cache vs. the on chip cache of the PPro. Bottom line: efficiency
varies, and how good it works out for you depends a lot on what you want to do
with it. Try before you buy, with your applications, if you can.
Personally, I just got this box a couple of weeks ago and haven't really done
much with it yet. I've been busy teaching this term and haven't had time to
play. However, I do have some research problems to work on, which is why I
bought this box in the first place; I'll be using custom-written software for
that. Oh, and BTW, it is *real* nice to be able to run TeX at light speed.
I haven't really found any Debian-specific issues with a multi-CPU setup; they
seem to be Linux issues, and the linux-smp mailing list (send mail to
majordomo@vger.rutgers.edu with "subscribe linux-smp", without quotes, in the
body of the message to subscribe) is a good place to get many of those
questions answered.
Good luck, and feel free to ask for more help if you do decide to go SMP.
Stephen Ryan
Team-OS/2 Debian GNU/Linux
Mathematics graduate student, Dartmouth College
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