Re: SMP scalability: 8 -> 32 CPUs

Jakub Jelinek (
Tue, 1 Dec 1998 10:03:54 +0100 (CET)

> Sun has clustering software available for Solaris. You can get four of
> those S10000's running as a single system.

Linux will be able to do clustering as well on E10000, in fact on E10k the
most of the work is done by the PROM and control board, so even when I was
testing Linux on E10k, it was booting in only one of the clusters, the other
one was driven by Solaris. But there are still several things to fix before
the E10k system will be running just fine, plus then we have to sit and do
some dynamic reconfiguration stuff, which won't be easy in Linux (especially
since we bypass kernel page tables on sparc64, probably we'll have to add
them during runtime if some memory is removed from the cluster (adding
memory should be not that hard, but not trivial either (holes in mem_map and
stuff like that)). CPUs add/removal should be more easy, AFAIK we don't have
anything special for boot CPU, with the exception of serial interrupts and
there are none on E10k, as it has no serial ports. The device stuff would be
normal rmmod/insmod probably, plus some PROM work to find out what happened.
> >
> > With all this talk of Linux not scaling past 8 CPUs, does this
> > imply that Linux will never be ported to the connection machine?
> > It is Sparc based after all. Speaking of which.... Sun borrowed
> > that technology when designing the E10000. Does that mean if
> > you load Linux up on that system you will only be able to
> > use 8 of the 64 CPUs?

No, you'll be able to use 64 CPUs, but it will not scale as nicely as it
should be.

Jakub Jelinek | |
Administrator of SunSITE Czech Republic, MFF, Charles University
Ultralinux - first 64bit OS to take full power of the UltraSparc
Linux version 2.1.130 on a sparc64 machine (3958.37 BogoMips)

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