To let nodes fail quickly, go find BIG primes with latest GMP nonstop at the
opterons.
After a few days of nonstop calculation bad nodes should get total hung,
when you hit worst case path.
most use prime95 for such stuff, but that thing is using exclusively "intel"
assembly SIMD code
and the cpu's seem quite well tested/fixed for SIMD.
Seems to me that a mix of integer multiplication and modulo there is worst
case path of those opteron chips.
It is of course also possible it hits a bug in the linux kernel, because my
own code doesn't get hung at all when running at 4 cores, whereas GMP did do
exactly that.
My code currently works fastest at windows, as it doesn't have inline
assembly for linux yet.
I wouldn't rule out that linux kernel simply has bugs there. The testing of
those kernels is total amateuristic.
Vincent
----- Original Message -----
From: "Tim Moore" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, December 04, 2006 4:15 PM
Subject: Re: [Beowulf] Node Drop-Off
Update to node drop-off:
I wrote a few weeks ago to ask about node drop-off. A quick note...I
had a cluster run for 3 years without failure and I upgraded the Opteron
240 CPUs to 250s. The upgrade required a BIOS upgrade and while I was
at it, upgraded the OS and security. Some readers provided good
suggestions for diagnosis. As it turned out, of the 16 CPU batch...two
were flawed. No success was derived from replacing power supplies, HDD,
resetting memory and the cooling solution. The CPU flaw only manifested
itself (at first) after several hours of CPU usage. With each failure,
the time duration shortened before the next failure and by the time I
figured it out was down to about 2 minutes.
The AMD engineer with whom I talked was amazed that such CPUs made it
beyond quality control. He also suggested that the vendor may have
inadvertently mixed returned (previously fetermined to be flawed
processors) with the new ones and sent them out (again) as new.
Just for future reference...is there an easy way to determine if a CPU
is flawed with 2 weeks of down time and extensive hair extraction????
Tim
--------------------------------------------------------------------------------
_______________________________________________
Beowulf mailing list, [email protected]
To change your subscription (digest mode or unsubscribe) visit
http://www.beowulf.org/mailman/listinfo/beowulf
_______________________________________________
Beowulf mailing list, [email protected]
To change your subscription (digest mode or unsubscribe) visit
http://www.beowulf.org/mailman/listinfo/beowulf
