Single or Multi Core

[stevieb]

I am currently looking into pgrading a few PC's on the office, all are Single Core P4-3gig at the moment but we are running out of processing power some of our applications are taking in some cases 1 week to finish off the modelling (Mainly calculations no Graphics involved at all)

Say if i were to upgrade to a top spec Dual core processor with the software not being wrtten specifically for dual core processing will i see an advantage in run times. currently in excess of 216 hours. I know i will not cut the run times in half but will they reduce????

Please dont tell me to use a linux server (48 Processors) or other sort as we do have one but is working on another project and is being used 24/7, and the software i am using is only windows based.

I need of a quick fix.

Thanks

[Plotloss]

P4 805D

Dual core barmyness for the price of a bad night out...

You can wind them up to, for power users...

[annodomini2]

Find out if there are any mb's that will run multiple chips with dual core.

Then put as many as you can on, Get the fastest RAM they will run and as much as will fit (within budget of course )

As it's windows, faster HDD may also help, the Raptor 10,000rpm drives a recommended on many websites.

[annodomini2]

The real question is does your software have multiprocessor support?

[dcw@pr]

Plotloss said:

P4 805D

Dual core barmyness for the price of a bad night out...

You can wind them up to, for power users...

just making one of these sytems today. goign to take it up to 3.6, or possibly 3.8. Got a raptor 74gb too. Got it all made at lunch time but then discovered they hadn't packed a 20-24pin power adapter, but should have one any minute now.

[pentoman]

I think he's saying the software isn't written for multi-processor support, but will it get faster anyway.

Is there some instruction level parallelism they can do what with having two cores? Or are they not connected at that low a level?

[stevieb]

pentoman said:

I think he's saying the software isn't written for multi-processor support, but will it get faster anyway.

Is there some instruction level parallelism they can do what with having two cores? Or are they not connected at that low a level?

Just want to know if it will use the second core to some extent. well i suppose the question is with windows try to farm out the work to both cores or will it do it through one core only?

[Plotloss]

The dual core processors act as two processors fed by one pipe I believe.

So the code doesnt have to be MPU aware, there are hardware level instructions that take care of all that.

[ATG]

Plotloss said:

The dual core processors act as two processors fed by one pipe I believe.

So the code doesnt have to be MPU aware, there are hardware level instructions that take care of all that.

I don't keep up to date with the terminology. Are the mulitcore processors we're talking about here the same as the "Xeon" procs from a few years ago? If so, the O/S certainly saw the thing as being two distinct procs and you could watch applications like SQL Server hitting one proc and then the other ... i.e. there was no sign of any low-level parallelism and software would have to be written specifically to take advantage of multiple processors.

[Plotloss]

Nah, Xeon was a normal processor with a bigger on die cache.

These new Dual Core jobs are two physical processors on the same die supplied by the same bus.

So the software just dumps what it needs processing in the one bus as usual and then each core takes a slice of the job in hand.

With Xeons in an MPU config you had two buses so the software had to be aware to dump a proportion of the processor load into the second bus to take advantage of the second or subsequent CPU

[scorp]

Plotloss said:

The dual core processors act as two processors fed by one pipe I believe.

So the code doesnt have to be MPU aware, there are hardware level instructions that take care of all that.

Is it threads or processes split between cores?

[Plotloss]

Good little explanation here: www.short-media.com/review.php?r=261

[aldi]

Pentium D's are two distinct processors, the app needs to be able to take advantage to see the most benefit. If not you'l just see one processor on 100% and the other on 0% in task manager. It might make the PC more responsive in other tasks while its processing though.

how's the RAM in these machines? check 'commit charge' vs 'physical memory' in task manager while the calcs are running.

[ATG]

Plotloss said:

Good little explanation here: www.short-media.com/review.php?r=261

Suggests that software has to be SMP aware to take advantage of the second core.

[Plotloss]

ATG said:

Plotloss said:

Good little explanation here: www.short-media.com/review.php?r=261

Suggests that software has to be SMP aware to take advantage of the second core.

True, if Dual Coreing was true SMP but its not.

There are, as mentioned hardware level switches to load balance as they are fed by a single bus.

Its not as efficient as an SMP or even MPU setup as they share a bus but its not fair to say that it doesnt make things run any faster either.

[Zad]

Plotloss said:

True, if Dual Coreing was true SMP but its not.

There are, as mentioned hardware level switches to load balance as they are fed by a single bus.

Its not as efficient as an SMP or even MPU setup as they share a bus but its not fair to say that it doesnt make things run any faster either.

Each core has it's own cache, which is obviously fed from the main memory (which on AMD systems is nowhere near being saturated anyway). As Wikipedia defines SMP as "Symmetric Multiprocessing, or SMP, is a multiprocessor computer architecture where two or more identical processors are connected to a single shared main memory", I'm not sure why Dual Core x86 CPUs aren't SMP?

I'm not being contentious, I just want to understand why my it isn't true SMP.

(Re: the question: If the number crunching is a single thread, then it may see a small amount of improvement due to the non-crunching threads being moved over to the secondary cpu)

[stevieb]

aldi said:

Pentium D's are two distinct processors, the app needs to be able to take advantage to see the most benefit. If not you'l just see one processor on 100% and the other on 0% in task manager. It might make the PC more responsive in other tasks while its processing though.

how's the RAM in these machines? check 'commit charge' vs 'physical memory' in task manager while the calcs are running.

The commit charge is frequently hitting the limit. What would you suggest i can do about this?

The machines have 2Gig of RAM, and the peak processor temp is hitting around 80degrees C.

Unsure of a way forward other than by using a faster processor faster HD but already running a SCSI 15000RPM disc in RAID ARRAY.

[aldi]

The limit on the task manager screen is the total of physical memory + pagefile so if your hitting that then it would indicate that more memory might help you.

I'd check what the maximum ammount of RAM the motherboard can hold is, and get that much. It's cheap enough these days! Get the max. speed the motherboard will take also.

Also, does the application thats doing the processing have the option for you to tell it how much memory it can use? If so, I'd make sure that it's set appropriatley and not to more than the ammount of physical memory in the system. More like say 1750MB in your case, to leave some room for the system & caching.


80 degrees is quite hot, is it a hot room? Might be worth checking the heatsinks for dust buildup. Have seen some of the big round retail P4 heatsinks suffer from a kind of mat of dust building up inbetween the fan and the heatsink after a year or two, on top of the tightly packed fins. Might be worth a quick peek to check that its clear. Also, if these are just generic desktop cases with an array of 15k drives in them, you might want another fan in there for the drives.

HTH
Neil

Edit: Kazzaa and Seti@Home screensavers are a big no-no also

Edited by aldi on Wednesday 2nd August 09:53

[stevieb]

aldi said:

The limit on the task manager screen is the total of physical memory + pagefile so if your hitting that then it would indicate that more memory might help you.

I'd check what the maximum ammount of RAM the motherboard can hold is, and get that much. It's cheap enough these days! Get the max. speed the motherboard will take also.

Also, does the application thats doing the processing have the option for you to tell it how much memory it can use? If so, I'd make sure that it's set appropriatley and not to more than the ammount of physical memory in the system. More like say 1750MB in your case, to leave some room for the system & caching.


80 degrees is quite hot, is it a hot room? Might be worth checking the heatsinks for dust buildup. Have seen some of the big round retail P4 heatsinks suffer from a kind of mat of dust building up inbetween the fan and the heatsink after a year or two, on top of the tightly packed fins. Might be worth a quick peek to check that its clear. Also, if these are just generic desktop cases with an array of 15k drives in them, you might want another fan in there for the drives.

HTH
Neil

Edit: Kazzaa and Seti@Home screensavers are a big no-no also

Edited by aldi on Wednesday 2nd August 09:53

I have checked all of the obvious and to be honest the room temp is a constant 22 degress (AirCon), the machines are less than 6 months old, all cleaned out and still hitting 80 degrees, changed the thermal compond and upgraded the heatsink...

Oh well back to central IT for another upgrade!

[ATG]

stevieb said:

... some of our applications are taking in some cases 1 week to finish off the modelling (Mainly calculations no Graphics involved at all)

Can you tell us what this app is? Was it written in-house or bespoke? What type of modelling is it doing?