Merge window opens, kgdb merged

Posted Apr 19, 2008 22:09 UTC (Sat) by joib (subscriber, #8541)
Parent article: Merge window opens, kgdb merged

As an aside, who makes 4096-way x86 machines (mentioned in the link about the x86 changes)?
They must be pretty specialized machines, as with 40-bit physical addresses, which is what is
found in current x86-64 cpu:s, they are limited to 1 TB total, or 250 MB/CPU.

Merge window opens, kgdb merged

Posted Apr 19, 2008 22:54 UTC (Sat) by sbergman27 (guest, #10767) [Link] (5 responses)

SGI Altix, I would think.  A terabyte is a terabyte.  Each processor can address any part of
it. That's ram, of course.  The architecture allows for 52 bits of virtual, or 4096 terabytes
of that.

There are, however, other difficulties to be overcome:

http://lwn.net/Articles/229873/

Merge window opens, kgdb merged

Posted Apr 20, 2008 1:37 UTC (Sun) by rsidd (subscriber, #2582) [Link] (4 responses)

As far as I know, SGI Altix is based on Itanium, not x86.  I haven't come across an x86
machine with more than 32 processor cores (8 socket, 4 core Barcelona).

Merge window opens, kgdb merged

Posted Apr 20, 2008 6:23 UTC (Sun) by Cato (guest, #7643) [Link] (3 responses)

SGI systems include x86 versions with this CPU count - for example, NASA recently bought an
Altix ICE blade server with 4096 Xeon CPUs:
http://www.sgi.com/company_info/newsroom/press_releases/2...

However, the line between this blade-based system and traditional Altix systems is not
entirely clear, though presumably with the right problem a blade server would be just as good.

Merge window opens, kgdb merged

Posted Apr 20, 2008 7:59 UTC (Sun) by trey (guest, #37500) [Link] (2 responses)

Not a single system image (SSI). Imho runs multiple instances of Linux kernel.

Big shared-memory x86 machines

Posted Apr 20, 2008 8:48 UTC (Sun) by joib (subscriber, #8541) [Link] (1 responses)

That's correct, Altix ICE (and Altix XE) are clusters. Each 2-socket node runs its own kernel,
and there is no shared memory between nodes, so inter-node communication is with message
passing (MPI).

AFAIK all big shared-memory machines SGI makes are Itanium-based.

I suspect the answer to this conundrum is that this changeset just increases some previous
x86-only max-cpu limit, and the mention of 4096-way machines refers to the Itanium-based SGI
Altix.

Big shared-memory x86 machines

Posted Apr 22, 2008 12:46 UTC (Tue) by knan (subscriber, #3940) [Link]

There are development going on inside SGI for future and one-off machines, you know. The patch
came from a SGI employee, and definitely is for x86-64. While their current big boxes are
IA64, future machines doesn't need to be...