dual intel xeon = 4 processor??

firebird79 · Aug 8, 2003

for those who are using xeon processor....need some input on this. if i had dual xeon processor which is HT enable, will it act as 4 processor?? coz i need a fast computer to run some solving problem. like ls-dyna which can support many processor(smp).

Krowa 02 · Aug 8, 2003

Theoreticly it is 4 cpus, but it really isnt, get it? You have 2 cpus which can run 2 threads each.

verbatim · Aug 8, 2003

its the cache thats split between the 2 threads prevetring it acting like 4 processors.

Krzysd · Aug 8, 2003

there is a motherboard out there that does support 4 cpu's for Xeons, not that cheap though.

mateo · Aug 8, 2003

It also depends on your OS. If you're running 2k, it has to be a version of 2k that supports 4 physical CPUs. XP can tell if its a HT CPU, but 2k can't.

You won't get true 4-way performance, same way as you don't get true SMP with a HT P4, so saying it equals 4 CPUs is off the mark. There is some improvement, however, but it depends on teh application; server stuff benefits the most.

firebird79 · Aug 10, 2003

huh, thanks for all the input! then i think i should go for true smp board! i just couldn't stand the old pc which took 32hr to crack out one result!

OC-NightHawk · Aug 10, 2003

A dual xeon board is a true SMP board.

JDXNC · Aug 10, 2003

Just go with a Dual Xeon or Opteron. A real 4 way Xeon requires different CPUs which cost a LOT more than the regular 2 way Xeons.

bulk88 · Aug 10, 2003

loner said:
It also depends on your OS. If you're running 2k, it has to be a version of 2k that supports 4 physical CPUs. XP can tell if its a HT CPU, but 2k can't.

You will need windows 2k Server (cheaper) ($180 legit if you know where to look) 2K Advanced Server (more expensive) ($250 legit if you know where to look), also you can use datacenter but you can't get that legit, except OEM'ed with a machine, and a uptime guarentee and reliabilty and service leval agreements.

OC-NightHawk · Aug 10, 2003

But unless you need a server you don't want any version of 2000 for a dual xeon. 2000 treats all the processors like physical processors which ends up slowing stuff down. XP and 2003 are the Windows OS versions of choice. Of course Linux is also up to the task for free.

firebird79 · Aug 16, 2003

operating system are not my concern here, coz i already plant to used unix as my base OS.

OC-NightHawk said:
2000 treats all the processors like physical processors which ends up slowing stuff down.

can anyone explain more clearly about this? i would like to know more about it. thanks

OC-NightHawk · Aug 16, 2003

load management. Since its two logical cpus shareing the same cache its ideal to move to the other logical processor on the same physical processor. Since 2000 can't tell the difference between the physical and logical processors it doesn't manage the load in a way that takes this into account.

dustybyrd · Aug 16, 2003

can anyone explain more clearly about this? i would like to know more about it. thanks [/B]

i believe hyperthreading works as "two processors" when there are two different "types" of calculations that need to be done at the same time (that will use different physical parts of the same processor). therefore if the processor needs to do two similar things at the same time...then hyperthreading doesn't help much...

where as two different physical processors will always be able to do two different or similar types of applications at the same time using two physical processors...

OC-NightHawk · Aug 16, 2003

"i believe hyperthreading works as "two processors" when there are two different "types" of calculations that need to be done at the same time (that will use different physical parts of the same processor). therefore if the processor needs to do two similar things at the same time...then hyperthreading doesn't help much..."

Actually its more like the second thread gets the remaining execution time scraps. It helps process more stuff faster overall, but its known to slow down some apps as a side effect.

"where as two different physical processors will always be able to do two different or similar types of applications at the same time using two physical processors..."

Each processors has its own dedicated execution units. Although unless a program is programmed to use both cpus it just widens the load you can carry at your designated processor speed. For instance my dual 2.93GHz Xeon rig in most cases is just a monster 2.93GHz system that can do a whole lot of things at once at full speed. Of course there are a few programs like Max and Maya that use all available processors and 2 cpus and HT and seriously speed up from it.

edit: for sake of clairity let elaborate on the fact that Max and Maya only benifit from it while rendering, not while animating or modeling. Those two parts are more dependent on the quality of your graphics card.

dustybyrd · Aug 16, 2003

Actually its more like the second thread gets the remaining execution time scraps. It helps process more stuff faster overall, but its known to slow down some apps as a side effect.

if that's how hyperthreading works, then how is that any different than a multitasking operating system like windows? (ie if you do one task in windows that uses 75% of the processor...you can still use the remaining 25% of the "single threaded" execution time scraps on another application)

shouldn't hyperthreading be a "bit better" than multitasking, which uses execution time scraps?

Each processors has its own dedicated execution units. Although unless a program is programmed to use both cpus it just widens the load you can carry at your designated processor speed. For instance my dual 2.93GHz Xeon rig in most cases is just a monster 2.93GHz system that can do a whole lot of things at once at full speed. Of course there are a few programs like Max and Maya that use all available processors and 2 cpus and HT and seriously speed up from it.

it's definitely true that a dual system only speeds things up when using a multithreaded program or trying to run more than one single (or multi) threaded cpu intensive program at once...

and on single cpu applications, dual systems at the same speed are actually slightly slower than single cpu systems...

OC-NightHawk · Aug 16, 2003

dustybyrd said:
if that's how hyperthreading works, then how is that any different than a multitasking operating system like windows? (ie if you do one task in windows that uses 75% of the processor...you can still use the remaining 25% of the "single threaded" execution time scraps on another application)

shouldn't hyperthreading be a "bit better" than multitasking, which uses execution time scraps?

Didn't say it was bad, but the second thread plays second fiddle to the first thread. iF the first thread uses all of the execution time thread two waits till next time. However this never happens, and is the reason why HT exists. HT helps multi tasking to a degree, but a true SMP machine will handle multitasking better. Especially when you multitask multipul demanding apps. Its not unusual for me to render in maya while folding two clients and writing code for a project at once.

dustybyrd said:
it's definitely true that a dual system only speeds things up when using a multithreaded program or trying to run more than one single (or multi) threaded cpu intensive program at once...

and on single cpu applications, dual systems at the same speed are actually slightly slower than single cpu systems... [/B]

They aren't that much slower. In a game its the difference of a few fps that you'd never notice unless the fps counter was displayed on screen. But you lose more speed trying to multitask on a single cpu system than you do from the overhead of a second physical processor.

I once heard a perfect analogy for this relationship.

A single processor is a sports car like a corvette. It can go real fast, but put it under a load and it slows down real fast.

A dual or higher is like a truck, slower but has a lot of torque. It can pull a lot of weight before it slows down, but lacks the high top speed. However the speed it lacks isn't significant. It catches up to the sports car on a hill because it can better maintain its speed from all the torque.

dustybyrd · Aug 16, 2003

Didn't say it was bad, but the second thread plays second fiddle to the first thread. iF the first thread uses all of the execution time thread two waits till next time. However this never happens, and is the reason why HT exists. HT helps multi tasking to a degree, but a true SMP machine will handle multitasking better. Especially when you multitask multipul demanding apps. Its not unusual for me to render in maya while folding two clients and writing code for a project at once.

i don't think that is exactly correct...

first, many programs can use 100% of the processor cycles (like seti)-----then by your logic hyperthreading wouldn't help with seti using all available cpu cycles (assuming seti was a "top priority" program and didn't acquiesce to other programs)....however, it's my understanding that hyperthreading greatly improves seti times...

They aren't that much slower. In a game its the difference of a few fps that you'd never notice unless the fps counter was displayed on screen. But you lose more speed trying to multitask on a single cpu system than you do from the overhead of a second physical processor.

I once heard a perfect analogy for this relationship.

A single processor is a sports car like a corvette. It can go real fast, but put it under a load and it slows down real fast.

A dual or higher is like a truck, slower but has a lot of torque. It can pull a lot of weight before it slows down, but lacks the high top speed. However the speed it lacks isn't significant. It catches up to the sports car on a hill because it can better maintain its speed from all the torque.

Click to expand...

i agree that a dual cpu system at the same speed as a single cpu system isn't that much slower on single cpu tasks...but it is about 5-10% slower...

also, i love that analogy....i think it fits well...a 500 horsepower diesel truck could pull many tons of weight up a hill...(like multiple programs)....but a 500 horsepower ferrari couldn't....but it will be faster if it only pulls itself up that same hill....

OC-NightHawk · Aug 16, 2003

dustybyrd said:
i don't think that is exactly correct...

first, many programs can use 100% of the processor cycles (like seti)-----then by your logic hyperthreading wouldn't help with seti using all available cpu cycles (assuming seti was a "top priority" program and didn't acquiesce to other programs)....however, it's my understanding that hyperthreading greatly improves seti times...

They'll use 100% of one logical processor. Remember that the two logical processors are sharing resources, you can't do 100% on both and be as fast as a true SMP because the one physical processor just doesn't have the same amount of execution time as two physical processors. I believe that setis times are not improved, they just run two clients at once and do more in the same amount of time with the machine. Which in my opinion evens out.

dustybyrd said:
i agree that a dual cpu system at the same speed as a single cpu system isn't that much slower on single cpu tasks...but it is about 5-10% slower...

also, i love that analogy....i think it fits well...a 500 horsepower diesel truck could pull many tons of weight up a hill...(like multiple programs)....but a 500 horsepower ferrari couldn't....but it will be faster if it only pulls itself up that same hill....

Nothing noticable. I don't physical sit there and say, damn my game is slow. I may only get 90fps on my games at all times, but I never see slowdown even when a heavy app is in the background.

I think you've got the analogy down.

But if you multitask a lot, you've always got a lad.

dustybyrd · Aug 17, 2003

They'll use 100% of one logical processor. Remember that the two logical processors are sharing resources, you can't do 100% on both and be as fast as a true SMP because the one physical processor just doesn't have the same amount of execution time as two physical processors. I believe that setis times are not improved, they just run two clients at once and do more in the same amount of time with the machine. Which in my opinion evens out.

i know it seems a bit weird...they actually can do more setis total in the same amount of time with hyperthreading enabled...

the reason i know is because the guy that sold me my dual AMD board sold it to me so that he could get a p4 hyperthreader and overclock it to 3.2+ghz and run seti...

i forget how much more seti's than my dual AMD but more....

OC-NightHawk · Aug 17, 2003

dustybyrd said:
i know it seems a bit weird...they actually can do more setis total in the same amount of time with hyperthreading enabled...

the reason i know is because the guy that sold me my dual AMD board sold it to me so that he could get a p4 hyperthreader and overclock it to 3.2+ghz and run seti...

i forget how much more seti's than my dual AMD but more....

Yeah they do more by running two clients. Thats what i said.

However I wouldn't go so far to say that a single P4 with HT is better than a true dual rig. Even a platform which imo is showing its age. The AMD rig could run two clients just as easily and more than likely smoke that P4 if your willing to overclock it.

dual intel xeon = 4 processor??

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