Dual processor vs. dual core

[rhys]

For performance and tax reasons I really should build a new "God box"
this year. In the past, I've built ASUS mobo-based dual Pentium II and
Pentium III boxes, and have been very happy with their performance
when multi-tasking. I use multi-thread- and multi-processor-aware apps
and OS, and know how to tweak for maximum sustainable speed.

Looking forward in the next six months, should I consider dual-core or
dual processor? Ideally, I use these machines for three to four years:
should I build with an eye to 64-bit OS needs? Opteron or Xeon or the
new Smithfield? Boards with good reputations (I've found ASUS
dependable for many years now).

Suggestions or just blue-skying is welcome. Money isn't a huge issue
as I change up machines less often than a true hobbyist: I require raw
business app power and multi-tasking ability, not gaming and not video
production, but yes, some high-end graphics.

Thanks,

R.

[John Doe]

... I use multi-thread- and multi-processor-aware apps
and OS, and know how to tweak for maximum sustainable speed.
Looking forward in the next six months, should I consider
dual-core or dual processor? ...
Suggestions or just blue-skying is welcome.

Seems to me that would be multi-processor. One thing for sure,
IMO, is that shopping online is the way to go for a system. Like
they used to say, let your fingers do the walking. Have fun.

[m***@sushi.com]

You might want to read up on dual opterons. My understand is this chip
set has memory allocated for each CPU such that both can use their own
ram at the same time:
http://www.tyan.com/products/html/thunderk8we.html
There is a provision for one CPU to read the other CPU's memory, and
vice versa. This eliminates a bottle neck in dual processors. It seems
dual core won't have this capability.

Personally, after building dual CPU systems, I just don't think it is
worth the extra cost. Better to upgrade later. The only thing building
a super system does is it prevents the downtime as you migrate from one
system to the other, which often isn't trivial. You know how much work
it is to get a system just right.

[rhys]

Post by m***@sushi.com
You might want to read up on dual opterons.

I have been. They intrigue me at both the price and performance point.
I think Xeons could be cheaper and cooler.

My understand is this chip

Post by m***@sushi.com
set has memory allocated for each CPU such that both can use their own
http://www.tyan.com/products/html/thunderk8we.html
There is a provision for one CPU to read the other CPU's memory, and
vice versa. This eliminates a bottle neck in dual processors.

Yes, it makes sense to max out the RAM then.


It seems

Post by m***@sushi.com
dual core won't have this capability.

That's why I've been wondering if it's an "applicable to me"
technology. I use the benefits of dual CPUs constantly, but I'm a sort
of niche market, which is why I custom assemble in the first place.

Post by m***@sushi.com
Personally, after building dual CPU systems, I just don't think it is
worth the extra cost. Better to upgrade later. The only thing building
a super system does is it prevents the downtime as you migrate from one
system to the other, which often isn't trivial. You know how much work
it is to get a system just right.

Yes, the tweaking and whatnot takes time and a certain amount of
expertise and expermentation. Still, I can get two sub-maximal CPUs in
terms of speed and cost to totally outperform the "fastest" single CPU
in the apps and environment I use.

Thanks,
R.

[m***@sushi.com]

Just to be clear here, it's not a matter of maxing out on ram as much
as each processor having a direct path to their own ram. That is why
there are so many memory sockets on the board. I believe this is unique
to the Opteron, i.e. you won't have the same memory structure using
Xeon processors.

Some programs really benefit from dual CPUs, such as photoshop. But you
don't get 2x the speed. A few programs actually are worse under dual
CPUs, but this is pretty rare. Tom's hardware has benchmarks on dual
CPU systems and generally you aren't getting much bang for your buck.

[rhys]

Post by m***@sushi.com
Just to be clear here, it's not a matter of maxing out on ram as much
as each processor having a direct path to their own ram. That is why
there are so many memory sockets on the board. I believe this is unique
to the Opteron, i.e. you won't have the same memory structure using
Xeon processors.

I think I understood that, but thank you for reiterating it. I have
been hearing generally that Opteron is a better deal not just in price
and performance but in clever engineering like this. What boards do
you recommend?

Post by m***@sushi.com
Some programs really benefit from dual CPUs, such as photoshop.

This would be a 2-D graphics workstation, using latest Photoshop (with
lots of batch processing), InDesign, Quark, Illustrator, Pagemaker,
and I do a LOT of Acrobat distills and PostScript work.

If I poll my e-mail or try to load a webpage during that sort of thing
on a single CPU machine, they go into a corner to have a good cry.

I realize that dual CPUs aren't the answer for many, but I've had them
since '97 and I run a mix of apps that recognize and use them
effectively under Windows NT (in '97) and now Windows 2000.


But you

Post by m***@sushi.com
don't get 2x the speed.

Understood. What you do get is the ability to run more programs in the
background without incurring page faults and exceptions.

A few programs actually are worse under dual

Post by m***@sushi.com
CPUs, but this is pretty rare. Tom's hardware has benchmarks on dual
CPU systems and generally you aren't getting much bang for your buck.

Except for me. Trust me on this. I haven't read anything in the last
two years about OSes and single processor improvements that seems to
negate the immediate benefits I get in desktop publishing and graphic
design from dual CPUs and a decent video card and bags of RAM.

The thing I can economize on are the hard drives, DVD drives, the
audio (basic) and I have a box of networking gear and retired routers
already.

R.

[m***@sushi.com]

First of all, I feel like an idiot for not suggesting you visit
http://www.2cpu.com/
I totally forgot about this website.

Most of the modern boards have one or two gigabit ethernets and audio
installed, so there isn't much to save buy owning such gear. .I'd go
with the Tyan board I put in the other post.

The only thing is these boards like to be stuff with identical RAM
modules. Since 32 bit windows can only handle 4G of RAM, you will have
to stuff all the sockets of the board with very small modules for all
the fancy features to work. Memory always has a sweet spot, i.e. there
is a spot where the cost per bit is the cheapest. I suspect you will be
on the low side of that curve. Maybe you should wait for the 64 bit OS
to come out.

I think if you are getting page faults, the problem is lack of ram and
not lack of a dual CPU. That is, you are doing swapping of memory and
perhaps the swap area of the disk is not so reliable. My notebook PC is
not a dually, and I don't have such problems.

You may be aware that some programs or hadware don't work with dual
processors. I had this trouble with my sound blaster live until they
fixed the problem. Some adaptec gear has disclaimers on dual CPU
operation as well.

Regarding disk drives. you might as well set up a raid system and
mirror the drives. The raid boards that you can stuff with ram should
get you an additional boost. This is where I'd spend the money instead
of going dual. However, it's really not that much more expensive for a
second CPU if it gives you some peace of mind.

[paak]

The major problem with Dual core is that it 'shares' things like the L1/L2
cache....imagine the performance loss when both cores running at high
capacity...

I would definately go with the Opterons. 64bit and integrated on-chip memory
controller being 2 of the biggest benefits.

Post by rhys
For performance and tax reasons I really should build a new "God box"
this year. In the past, I've built ASUS mobo-based dual Pentium II and
Pentium III boxes, and have been very happy with their performance
when multi-tasking. I use multi-thread- and multi-processor-aware apps
and OS, and know how to tweak for maximum sustainable speed.
Looking forward in the next six months, should I consider dual-core or
should I build with an eye to 64-bit OS needs? Opteron or Xeon or the
new Smithfield? Boards with good reputations (I've found ASUS
dependable for many years now).
Suggestions or just blue-skying is welcome. Money isn't a huge issue
as I change up machines less often than a true hobbyist: I require raw
business app power and multi-tasking ability, not gaming and not video
production, but yes, some high-end graphics.
Thanks,
R.

[rhys]

Post by paak
The major problem with Dual core is that it 'shares' things like the L1/L2
cache....imagine the performance loss when both cores running at high
capacity...
I would definately go with the Opterons. 64bit and integrated on-chip memory
controller being 2 of the biggest benefits.

Assuming I go with a pair of them, any suggestions as to boards,
chipsets, best RAM and appropriate power supplies? I don't care if I
have to go WTX, but as I won't run more than one video card and no
more than three drives, I wouldn't mind avoiding "specialty" cabling
and connectors, i.e. sticking with the ATX form factor (now that BTX
seems to be in a coma, that is).

I don't overclock my main rigs, by the way, and I am putting a premium
on my next dual CPU rig being as quiet as possible.

R.

Post by paak

Post by rhys
For performance and tax reasons I really should build a new "God box"
this year. In the past, I've built ASUS mobo-based dual Pentium II and
Pentium III boxes, and have been very happy with their performance
when multi-tasking. I use multi-thread- and multi-processor-aware apps
and OS, and know how to tweak for maximum sustainable speed.
Looking forward in the next six months, should I consider dual-core or
should I build with an eye to 64-bit OS needs? Opteron or Xeon or the
new Smithfield? Boards with good reputations (I've found ASUS
dependable for many years now).
Suggestions or just blue-skying is welcome. Money isn't a huge issue
as I change up machines less often than a true hobbyist: I require raw
business app power and multi-tasking ability, not gaming and not video
production, but yes, some high-end graphics.
Thanks,
R.

[signmeuptoo]

On the coming Dual Core AMD 64 CPUs, the L1 cash will be separae, and the
L2 will be shared, and there are advantages in that. There will be a
"crossbar switch" between them, on die between the CPUs and the memory
controller. It looks like it will be a great thing. I seem to remember
that there was some advantage to having the crossbar switch and shared L2
cache, I think it was because round trips were reduced or something, but I
might be wrong.

Post by paak
The major problem with Dual core is that it 'shares' things like the L1/L2
cache....imagine the performance loss when both cores running at high
capacity...
I would definately go with the Opterons. 64bit and integrated on-chip memory
controller being 2 of the biggest benefits.

Post by rhys
For performance and tax reasons I really should build a new "God box"
this year. In the past, I've built ASUS mobo-based dual Pentium II and
Pentium III boxes, and have been very happy with their performance
when multi-tasking. I use multi-thread- and multi-processor-aware apps
and OS, and know how to tweak for maximum sustainable speed.
Looking forward in the next six months, should I consider dual-core or
should I build with an eye to 64-bit OS needs? Opteron or Xeon or the
new Smithfield? Boards with good reputations (I've found ASUS
dependable for many years now).
Suggestions or just blue-skying is welcome. Money isn't a huge issue
as I change up machines less often than a true hobbyist: I require raw
business app power and multi-tasking ability, not gaming and not video
production, but yes, some high-end graphics.
Thanks,
R.

[rhys]

On Fri, 15 Apr 2005 07:58:11 GMT, signmeuptoo

Post by signmeuptoo
On the coming Dual Core AMD 64 CPUs, the L1 cash will be separae, and the
L2 will be shared, and there are advantages in that. There will be a
"crossbar switch" between them, on die between the CPUs and the memory
controller. It looks like it will be a great thing. I seem to remember
that there was some advantage to having the crossbar switch and shared L2
cache, I think it was because round trips were reduced or something, but I
might be wrong.

Thanks for this. I would love to hear from someone already using dual
Xeon or Opterons in the real world, and where they see an upgrade
path.

R.