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World Community Grid Forums
Category: Support
Forum: Suggestions / Feedback
Thread: What about my 2nd CPU? (it wants to play too) |
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Thread Status: Active Total posts in this thread: 30
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hnapel
Advanced Cruncher Netherlands Joined: Nov 17, 2004 Post Count: 82 Status: Offline Project Badges: 
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hyperthreading is partly a fake from intel (AFAIK), it presents the OS with two CPU's while really there's only one, the advantage being the system is
more reponsive . maybe someone can test if you disable hyperthreading in the bios, the grid program can complete its task faster having the CPU all for itself (minus the 1% you use for your wordprocessor) |
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
Does anybody know what happens if you run it on two processors?
My progress bar is slowing down (or lets say at least not speeding up) when I run it on both CPUs (HT). Does it calculate something else on the other CPU, wich you cannot see by clicking on the icon in the task bar or is this a waste of CPU power? |
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c.h.m.p. willems
Cruncher Joined: Nov 16, 2004 Post Count: 2 Status: Offline |
Well i know there was a program called UDTweaker for the UD client. I don't know if it works with this client? UDTweaker is at http://blakenyc77.tripod.com/udtweaker.html and will probably work, because the WCG and UD Agent are very similar. It works fine, but when I restarted my computer I lost all data  . Be carefull!!!! |
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olebole
Cruncher Joined: Nov 25, 2004 Post Count: 12 Status: Offline Project Badges: 
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Hi, Is there any way to make this app use both of my CPUs? I have a dual Opteron 248 with 4GB of memory, so it seems like a waste of time to me, having one of these CPUs doing nothing. mil Otherwise some guy over at the UD forums wrote a guide detailing how you can "cheat" windows into allowing two instances of the client to be run at the same time. Very briefly: You need to run Windows XP, because it will allow you to have two users logged on at the same time. You then install to copies of WCG in two separate dirs and create two users on your XP system. You then make a shortcut to the ud.exe and go to the properties of this shortcut and choose "compatibility" and select the "Windows NT 4.0 (Service Pack 5)" mode. You have to repeat this procedure for both shortcuts (one on each users desktop). This will allow two instances to be run at the same time. This was the condensed version. Go over to the UD forums and check out further details if this doesn't work for you. It works fine with me. |
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David Autumns
Ace Cruncher UK Joined: Nov 16, 2004 Post Count: 11062 Status: Offline Project Badges: 
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
Lame. Compile a real multi-threaded app, please. |
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
Well i know there was a program called UDTweaker for the UD client. I don't know if it works with this client? UDTweaker is at http://blakenyc77.tripod.com/udtweaker.html and will probably work, because the WCG and UD Agent are very similar. I hate to be the bearer of bad news, but if you follow the link on the UD Tweaker website to the grid.org forums, you will find that United Devices -- who makes the software for that grid project and this one (they're virtually identical -- a few thousandths of a version number -- and I've run Rosetta from both) -- does not recommend UD Tweaker because A) It corrupts results and B) It is not necessary if you are just using hyper threading. Supposedly if you read the whole thing UD says that UD Tweaker uses an unsupported switch in the program that never was fully debugged. You end up returning results (and possibly getting points) but they will be corrupted and you will have accomplished nothing. The reason you don't need UD Tweaker on a hyper threaded pentium 4 is that there is really only one CPU with one floating point processor, but the operating system is tricked into seeing 2 processors. So even though you only see 50% utilization you are really hitting the FPU at 100%. By using UD tweaker you see 100% utilization, but what is really happening is that instead of processing 1 work unit at 100%, you are now processing two work units at 50%. This is less efficient and it would run faster if you didn't run UD Tweaker. This is all according to UD and I have to think that they would have endorsed UD Tweaker if it worked or at least given silent approval. It certainly seems that no one at grid.org is using UD Tweaker. That said, I do think that United Devices should get their heads out of the sand and finally write a program that can handle multiple processors and run on linux and macs. Read it for yourself here: http://forum.grid.org/phpBB/viewtopic.php?t=4624 |
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Alther
Former World Community Grid Tech United States of America Joined: Sep 30, 2004 Post Count: 414 Status: Offline Project Badges:
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Does anybody know what happens if you run it on two processors? My progress bar is slowing down (or lets say at least not speeding up) when I run it on both CPUs (HT). Does it calculate something else on the other CPU, wich you cannot see by clicking on the icon in the task bar or is this a waste of CPU power? Welcome to Intel marketing. That's because you don't have two CPUs. You have one CPU that tricks the OS into thinking it has two. There are many documented benchmarks showing that HT may cause a degradation in performance (thrashing the CPU). Likewise, there are conditions where HT improves performance, but it's never the equivalent of two actual CPUs (not even close). The reality is that with HT turned on and running WCG, your CPU is close to 100% utilization even though Task Manager shows it as only 50% utilized. That's because it actually thinks there are two CPUs and it's reporting the utilization of "both" (one at 100%, the other at 0% thus the 50% overall utilization you are seeing).
Rick Alther
----------------------------------------Former World Community Grid Developer [Edit 1 times, last edit by Alther at Dec 10, 2004 10:51:40 PM] |
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
Does anybody know what happens if you run it on two processors? My progress bar is slowing down (or lets say at least not speeding up) when I run it on both CPUs (HT). Does it calculate something else on the other CPU, wich you cannot see by clicking on the icon in the task bar or is this a waste of CPU power? Welcome to Intel marketing. That's because you don't have two CPUs. You have one CPU that tricks the OS into thinking it has two. There are many documented benchmarks showing that HT may cause a degradation in performance (thrashing the CPU). Likewise, there are conditions where HT improves performance, but it's never the equivalent of two actual CPUs (not even close). The reality is that with HT turned on and running WCG, your CPU is close to 100% utilization even though Task Manager shows it as only 50% utilized. That's because it actually thinks there are two CPUs and it's reporting the utilization of "both" (one at 100%, the other at 0% thus the 50% overall utilization you are seeing). This is all correct. There are, however, situations where certain applications, which are properly written to handle multiple threads with simultaneous execution, can benefit from Intel's Hyperthreading. Sadly, the agent used for this project is not one of them... it uses a single thread and cannot take advantage of the ability to process multiple threads simultaneously, and then sync the end results, which is how you take advantage of dual processors. Hyperthreading is useful for instances where the CPU is not being used to it's full extent. Basically, the system can launch other, single-threaded programs and deal with their needs using any excess processing power. In multi-threaded apps, if one thread does not use the full processing power, other threads can go to the other "virtual" processor to complete the job quicker by more effectively utilizing the full potential power of the processor. In summary, hyperthreading is neat, but you do not actually have dual processors, unless you have dual processors, if you get my drift. (In which case your OS would think you have four!) In hardcore number-crunching projects such as our scenarios, or 3D rendering, etc., only "real" additional processors can lend a hand to the process. Until the software is re-written to take advantage of true SMP systems, the only good your second processor will be is handling background system functions without disturbing the processor that is crunching the work units. So be aware and happy that your second CPU isn't totally useless for this project; it DOES help, just not as much as we'd like. The client used in this project has no trouble utilizing the CPU to it's fullest, so there is no excess processing power available to handle other threads. That's why HT is of no real use in this sort of project, only an actual second processor would be. IF the client knew what to do with it. As things are now, the OS handles things by giving one processor entirely over to the client and using the second processor for all other background system tasks. At least, that's how it works in an ideal world.  Say, Mr. Alther, any rough timetable on a software revision yet? *hope-hope* |
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Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
The last 3 posts are very good information!
Thanks for clearing things up, gbo2, Rick, and CompuDude. |
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