Read somewhere today ( wish i remembered where ) that if the budget is
limited and the option are:
Dual Opteron 250 CPU
OR
One CPU 275 ( dual core )
You should go on the single 275.
one of the reasons was the balancing between two real cpus slow the
performance.
Im wondering if that true.
Gilboa Davara wrote:
Shachar,
There's no single answer to your question; in-order to give you better
answer I'll need some further information about your software.
Here's a couple of points that you might find interesting: (I mostly
do kernel-level network streaming/filtering work, so YMMV)
* The AMD Opteron *is* the King of the Hill. I found that "my" HP 385
(Opteron 248/250) and older IBM e326 (Opteron 246/248) to be able to
outperform a similarly configured (and priced) Xeon 2.8/3.4/3.6 (DL
380, IBM e345) hands down. Highly memory and I/O intensive
applications like my own (which spends days btree searching and
memXXX-ing itself to death) seem to *greatly* favor the Opteron's
on-die memory controller. (compared to the Xeon's traditional
north-bridge design). I'm still looking for ways to use the Opteron
NUMA support; I *assume* that xxx_alloc_node will further improve
performance.
* The dual core option is a true winner. Even the relatively cheap
(?!?!) Opteron 265 machine can run circles around a quad Xeon MP
machine. (Shared bus designed never really favored > 2 CPU
configuration.) At less then 1000$ per 265 CPU, building a dual - dual
core workstation / server is pretty inexpensive. (I plan on upgrading
my private dual Opteron workstation to dual core once I find someone
that's willing to buy my left kidney...)
* The GCC's x86-64 AMD64 optimization favor the Opteron greatly. Only
when we optimized our code with -march=nocona we managed to level the
playing field a *bit*. Somehow Intel seem to have skimped a little
when it they duplicated the AMD64 (s/EM64T/AMD64/g)
As far as I remember the Debian AMD64 port is using -march=nocona to
help the Xeon save face. (Same goes for my FC4/x86-64 machines)
* The Xeon might close the gap if you have highly hyper-theadable code
(little or no I/O [including memory I/O] with a lot of integer
calculations). In such a (remote?) case, you might actually see a
10-15% gain per socket, maybe even slightly outperforming the Opteron.
However, if you plan on using more then two sockets (dual), a shared
400/533Mhz bus doesn't play nice with Hyper-threading enabled. In
general I'd stir clear of Hyperthreading on dual - or -above machines.
* Might sound weird... but while working on my previous project we saw
instances where an older 2.8Ghz 533Mhz (Prestonia?) Xeon was able to
outperform the 3.0Ghz 800Mhz Nocona Xeons. Go figure.
* The Itanium (1.4Ghz, Medison core?) has lousy Integer performance
and memory performance. Don't touch it. (Or you'll burn... literally...)
In general I find the Opteron to be the superior platform. But again,
we conducted out tests with our software, so YMMV (greatly).
Hope it helps,
Gilboa
On Sun, 2005-08-07 at 14:52 +0300, Shachar Shemesh wrote:
Hi all,
I'm looking into buying a computation server for a client. They are
looking for the platform that will give them optimal INTEGER
performance. I'm thinking between the 64Bits - PowerPC, Itanium and the
EMT64/AMD64 technologies. I am also interested in more specific
knowledge ("Xeon is better than Athelon" etc.).
Thoughts? Ideas?
Any solution picked will be running Debian Linux (Sarge), and the
program will likely be compiled with gcc (whatever version will work best).
Thanks,
Shachar
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