Re: [gentoo-alpha] Problems with SMP on Alpha UP2000+

[Matt Turner <mattst88@gentoo.org>]

On Sat, Jun 4, 2011 at 6:23 PM, Magnus Lindholm <linmag7@gmail.com> wrote:
> Hi,
>
> I have a UP2000+ system with dual 21264 @ 667MHz/4MB cache and 2GB RAM. The
> system runs fine with RedHat 7.2 Linux (downloaded from hp website) with an
> 2.4 SMP kernel. However, running Gentoo with an SMP kernel will eventually
> make the system freeze (i.e make -j2 when building a new kernel only lasts
> for a 30 seconds or so). I've also tried NetBSD-5.1, FreeBSD-6.4, and a few
> other Linux distros with the 2.6 kernel (make -j2 makes the system freeze).
> It seems like Linux kernel 2.4 is the only OS that works with SMP on my
> system. Has anyone else experienced something similar with an UP2000+ Alpha
> system? First I suspected faulty hardware, but RedHat 7.2 seems to work just
> fine so...
>
> I heard somewhere that Linux going from 2.4 to 2.6 made some significant
> re-structuring of the SMP code that broke SMP support on some systems?
>
> The system has a Matrox Millenium and a 3Com 3c509B Ethernet card and a SCSI
> disk hooked up to the on-board SCSI. I've tried unplugging the NIC and a
> using a DEC PowerStorm 3D30 in stead of the Matrox Millenium, different CPU
> modules and different RAM modules. All with the same results. There are no
> error messages to be seen anywhere when the system freezes up.
>
>
> Regards
>
> Magnus

It's been my experience that UP2000s are quite fragile. Not entirely
sure if it's the Cchips/Dchips on the board or the CPUs themselves.
Maybe the SMP scheduler in 2.4 isn't good enough to sufficiently load
both CPUs or something. Anyway, this doesn't seem to be an uncommon
problem at all.

If you're in Europe, I have a bunch of 833 MHz Slot B CPUs living with
a friend in Finland. Perhaps you'd like to give a pair of these a try
and if they work, buy them?

Get on IRC, #alpha and #gentoo-alpha on Freenode and let's talk.

Thanks,
Matt