Issue with more than 16 cores ? {Nope}

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Re: Issue with more than 16 cores ?

Postby Tsagoth » Sat Dec 17, 2011 5:23 pm

I changed the priority, and it did make a small difference; the core now shows as 96-89% usage.

One thing that Resource Monitor shows that I don't quite understand is that under Processes fah_core is ~ 90%. Under Services it says Network Store Interface Service is 15% and DHCP Client is 12%. I'm not very familiar with Server 2008 R2 so I don't really know why those services are running so high.

TPF is ~22 minutes, so I'm going to kill the client as it won't make the deadline. For whatever reason, this machine just isn't suited for folding.
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Re: Issue with more than 16 cores ?

Postby codysluder » Sat Dec 17, 2011 9:26 pm

I don't know about Network Store Interface Service, but DHCP should never consume 12%. My guess is that either you have acquired a virus or your machine might be busy serving a lot of files for others if you happen to be running a BitTorrent client. In fact, Network Store Interface Service is probably something that BitTorrent would use heavily when others are reading the files you're sharing.

The machine is fine for folding, but you have to decide what you want your machine to be doing.
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Re: Issue with more than 16 cores ?

Postby Tsagoth » Sat Dec 17, 2011 10:24 pm

It's not torrenting. It's not serving files. As soon as I stop the client, Network Store and DHCP go to zero. As soon as I start the client they also start back up. Obviously the client is doing something that makes use of those services.
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Re: Issue with more than 16 cores ?

Postby PantherX » Sun Dec 18, 2011 3:48 am

Could you please report back with your findings of -smp 12 or -smp 16 or -smp 20 as suggested in the previous posts?
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Re: Issue with more than 16 cores ?

Postby Ravage7779 » Sun Dec 18, 2011 4:11 pm

Tsagoth wrote:Well Coretemp works and it shows temps ranging from 54-71C for the cores while it's running P6984, limit is 101C. Taskmgr shows 95-98% usage by FahCore_a3. I don't know what the TPF is, I've let it run 15 minutes now and it hasn't finished a frame yet, so I presume it's hosed.


If core temp shows a high of 101F, you are overheating and your processor is downclocking to save its bacon. This would be your problem. Not quite sure if thats what you are stating there tho.
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Re: Issue with more than 16 cores ?

Postby k1wi » Sun Dec 18, 2011 5:50 pm

Ravage7779 wrote:
Tsagoth wrote:Well Coretemp works and it shows temps ranging from 54-71C for the cores while it's running P6984, limit is 101C. Taskmgr shows 95-98% usage by FahCore_a3. I don't know what the TPF is, I've let it run 15 minutes now and it hasn't finished a frame yet, so I presume it's hosed.


If core temp shows a high of 101F, you are overheating and your processor is downclocking to save its bacon. This would be your problem. Not quite sure if thats what you are stating there tho.

He's saying that his temperatures are 54-71 C, while his CPUs are rated to 101C.
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Re: Issue with more than 16 cores ?

Postby Tsagoth » Tue Dec 20, 2011 12:40 am

I've just run some trials and this is what I find for P6984:

smp 12: TPF = 2:34
smp 16: TPF = 16:13
smp 20: TPF = 01:49
smp 24: TPF = 02:28

During these runs Network Store and DHCP remained at zero cpu usage. smp 20 is the clear winner here.
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Re: Issue with more than 16 cores ?

Postby Tsagoth » Tue Dec 20, 2011 12:48 am

It occurs to me that -smp or -smp 24 spawns too many threads. I see 28 threads running in those cases, so presumably a random set of 4 threads starves, whereas in smp 20 all 24 threads have a processor available to execute them on demand.
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Re: Issue with more than 16 cores ?

Postby Zagen30 » Tue Dec 20, 2011 1:04 am

That really doesn't sound right, as the client should only spawn as many threads as there are cores when a thread count is not specified, and should definitely only spawn a specified number of threads. Is it possible that there's a second client running 4 threads, or 4 uniprocessor clients running?

EDIT: Evidently I'm wrong, so ignore my concerns.
Last edited by Zagen30 on Tue Dec 20, 2011 4:19 am, edited 1 time in total.
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Re: Issue with more than 16 cores ?

Postby Napoleon » Tue Dec 20, 2011 1:14 am

Actually, some extra FAHcore threads are supposed to be there. Only the specified amount of threads are scheduled to fold actively, the "extras" just linger there, waiting to deal with rare events like timered checkpoints, to pass interprocess messages between the client and the core, and so on.

EDIT: Having said that, with such a large number of available CPU cores/threads, it actually makes sense to back off from maximal SMP threads a little. That indeed leaves other background tasks unrelated to folding some room to maneuver. Since SMP is only as fast as its slowest thread - just like a fleet is only as fast as its slowest ship - leaving a small headroom for non-FAH background stuff may in fact yield better TPF.

20 threads should be an excellent choice in this case, it can be be factored to 2x2x5, whereas e.g 22 threads would be 2x11. IIRC, some people have reported simulation instabilities with -smp 7 and -smp 11. Although those should be very rare occurrences, it may be wise to stick with as small factors as possible.
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