Mark Hahn wrote:
I have been working on itanium machines for a year now and I actually
found
the hw pretty elegant and the dev software stack on top of it (compiler,
profiler etc) pretty handy.
aren't all the same tools available on x86_64? or were you referring
to, eg,
something SGI-specific?
Actually I'm using an itanium in an HP-integrity server. The tools I'm
referring to are the HP C and C++ compiler and their profiler called
caliper.
The C compiler for instance can add memory-debugging code (do not know
any compiler with a similar feature, valgrind nevertheless is more
powerfull). Next caliper allows to get a lot of diagnostics from the cpu
(also because ia64 supports all that while x86-64 does not AFAICT) like
number of bubbles in the pipeline, L2-cache misses, clock-cycles per
line of C-code etc.
but now with the Tukwila switching to the QuickPath, how do you guys
think
Itanium will perform in comparison to Xeon's and Opteron's ?
this change would be interesting if it meant that the next-gen numalink
box could take nehalems rather than ia64. I can't really understand why
Intel has stuck with ia64 this long - perhaps the economy will provide
the fig-leaf necessary to dump it.
Are you sure nehalem will outperform ia64. I will probably switch from
ia64 to x86-64 and knowing that my code is mostly memory-bound, I'm
wondering what I will gain. Of course the only way to know is to test
it but that has not been possible yet.
(why am I down on ia64? mainly the sense of unfulfilled promise: the
ISA was
supposed to provide some real advantage, and afaikt never has. the VLIW-ie
ISA was intended to avoid clock scaling problems created by CISC decode and
OOO, no? but the ia64 seems to have only distinguished itself by
relatively
large caches and offering cache-coherency hooks to SGI. have other
people had the experience ia64 doing OK on code with
regular/unrollable/prefetchable data patterns, but poorly otherwise?)
I'm not able to compare yet because I have not run the code on anything
else than ia64. But caliper allowed me to get a lot of diagnostics on
the cpu while running my code that allowed me to optimise easily.
t
_______________________________________________
Beowulf mailing list, Beowulf@beowulf.org
To change your subscription (digest mode or unsubscribe) visit
http://www.beowulf.org/mailman/listinfo/beowulf
